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General Information on Boa Const

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					BOA CONSTRICTORS (BOA CONSTRICTOR) SIAR ANTHRANIR REPTILES CHARLES R. SMITH AUSTIN, TX EMAIL: CRinAustin@att.net ©1999 Siar Anthranir Reptiles TABLE OF CONTENTS GENERAL BACKGROUND INFORMATION.................................................................................................1 Systematics..................................................................................................................................................1 Color and Pattern Variation .....................................................................................................................1 Natural History ..........................................................................................................................................4 Use by Man .................................................................................................................................................5 HERPETOCULTURE ..........................................................................................................................................5 Temperament and Handling .....................................................................................................................5 Housing .......................................................................................................................................................6 Food and Water..........................................................................................................................................7 Growth ........................................................................................................................................................8 Reproduction ..............................................................................................................................................9 Health ........................................................................................................................................................13 Colds ..............................................................................................................................................13 Pneumonia......................................................................................................................................13 Mouth Rot (Stomatitis) ..................................................................................................................13 Starvation (Inanition) .....................................................................................................................14 Inclusion Body Disease..................................................................................................................14 Amoebiasis .....................................................................................................................................14 Cryptosporidium spp. .....................................................................................................................14 Cestodes, Nematodes, Trematodes, and Lingulatids .....................................................................14 Mites, Ticks, and Lice ....................................................................................................................15 Scale Infections (Blister Disease orVesicular Dermatitis).............................................................15 Problems with Shedding (Dysecdysis) ..........................................................................................15 REFERENCES .....................................................................................................................................................16 TABLES AND FIGURES Table 1. Distribution and Dorsal Pattern of Subspecies of Boa Constrictor. .................................................2 Table 2. Meristics of Subspecies of Boa Constrictor. ........................................................................................3 Figure 1. Range Map of Boa Constrictor Subspecies and Other New World Boids. .......................................3 Table 3. Feeding Schedule. ..................................................................................................................................7 Figure 2. Weight-Length Relationship of Boa Constrictors in Colony. ...........................................................8 Figure 3. Growth in Length through Time. .........................................................................................................9 Figure 4. Growth in Weight through Time. ........................................................................................................9 Table 4. Sexual Dimorphism in Boa Constrictors. ...........................................................................................9 4.1. Literature Records of Caudal Plate Numbers in Males and Females..............................................9 4.2. Caudal Plate Numbers of Males and Females in the Colony. .......................................................10 4.3. Tail Length as a Percentage of Total Length for Males and Females in the Colony. ...................10 Figure 5. Caudal Plate Numbers for Males and Females in the Colony. .......................................................10
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Figure 6. Tail Length as a Proportion of Total Length for Males and Females in the Colony. ...................10 Figure 7. Period of Gestation from Time of Ovulation to Parturition for Six Females in the Colony. .......11 Figure 8. Numbers of Live Births and Other Eggs (Unfertilized Ova or Stillbirths) Produced in the Colony. .................................................................................................................................................12 PHOTOGRAPHS Photo 1. Boa constrictor imperator from coastal Tamaulipas, Mexico. ............................................................4 Photo 2. Two-year-old Boa constrictor constrictor born in captivity. ...............................................................4 Photo 3. Fatty tumors. ..........................................................................................................................................6 Photo 4. Midbody swelling in an ovulating boa constrictor. ...........................................................................11 Photo 5. Copulation in boa constrictors. ...........................................................................................................11 Photo 6. Late-term pregnancy in a thermoregulating boa constrictor. .........................................................11 Photo 7. 40 baby B.c. constrictor. .......................................................................................................................11 Photo 8. Identical twin neonates. .......................................................................................................................12 Photo 9. Operation to remove retained eggs and uterine horns/oviducts ......................................................12 Photo 10. Uterine horns with retained eggs. Oviducal torsion preventing passage of the ova. ..................13

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General Background Information Systematics The boa constrictor (Boa constrictor) is a heavy-bodied lowland tropical snake ranging from northern Mexico through Central America to northern Argentina. Forcart (1951) treats the Genus Constrictor as a synonym of Boa with the single species constrictor. Surprisingly, the boa constrictor is closely related to three species of Malagasy boas. This biogeographic distribution of reptiles in both tropical America and Madagascar also occurs in iguanine lizards and sideneck turtles. The relationship is so close that Kluge (1991) recommends the transfer of the Malagasy boas to the Genus Boa. Because of various taxonomic conventions, he suggests the following names: Boa madagascarensis (Acrantophis madagascarensis) for the Madagascar ground boa, B. dumerili (Acrantophis dumerili) for Dumeril's boa, and B. manditra (Sanzinia madagascarensis) for the Madagascar tree boa. Systematists currently recognize nine or ten poorly differentiated constrictor subspecies (Forcart 1951, Stimson 1969, Peters and Orejas-Miranda 1970, Langhammer 1983, Price and Russo 1991), three of which occur only on individual islands in the Gulf of Panama and the Lesser Antilles (Tables 1 and 2, Figure 1). The Mexican or Central American boa constrictor, imperator (Daudin 1803), is the northernmost race found from Mexico to northwestern South America. The common boa constrictor, B. c. constrictor Linnaeus 1758, is the most frequently imported subspecies, lives throughout Amazonian South America, and includes several "redtail" forms. B. c. ortonii Cope 1877, the Peruvian "redtail" boa constrictor, represents a restricted coastal population with a pale coloration but otherwise very similar to imperator. Langhammer (1983) suggests that it might best be relegated to the synonymy of imperator. B. c. occidentalis (Philippi 1873), the Argentine or pampas boa constrictor, and amarali, the Amaral's (or Brazilian or Bolivian) boa constrictor, occur to the south of constrictor as fairly widespread races. The remaining subspecies have very restricted ranges and, in most cases, questionable statuses. B. c. orophias (Linnaeus 1758), the St. Lucia boa constrictor, and nebulosa Lazell 1964, the clouded or Dominica boa constrictor, occur on Caribbean islands. B. c. sabogae (Barbour 1906), the Taboga Island boa constrictor, is restricted to an island in the Gulf of Panama and represents a reddish color variant of the mainland imperator. Synonymy with imperator has been suggested, but supporting data have not yet been published (Langhammer 1983). B. c. melanogaster Langhammer 1983, the black-bellied boa constrictor, occurs in the upper Amazon rainforest of eastern Ecuador, but Price and Russo (1991) question the validity of this subspecies. B. c. longicauda Price and Russo 1991, the long-tailed boa constrictor, has a dark anerythristic coloration and proportionately long tail compared to other boa constrictor races. It has been reported only from Tumbes Province, Peru. Several previously described races have been synonymized with adjacent subspecies. Peters and OrejasMiranda (1970) include B. c. mexicana (Jan 1863) from Mexico, B. c. isthmica Garman 1883 from Panama, and B. c. eques (Eydoux and Souleyet 1842) from Peru in the synonymy of imperator. Zweifel (1960) synonymized the Mexican race sigma, the Tres Marías Islands boa constrictor described from María Madre Island by Smith (1943), with the mainland form imperator, though others have questioned this action (Langhammer 1983). Lazell (1964) refers B. c. diviniloqua (Duméril and Bibron 1844) to orophias, the St. Lucia boa constrictor. Color Pattern and Meristic Variation Considerable variation in color pattern exists both within and between subspecies (Table 1), especially with regard to insular and coastal forms. Many Boa constrictor populations exhibit reddish coloration of the tail and elsewhere (see below), but the redtail forms have no taxonomic status. Some amazing varieties, including albino and patternless forms, recently have been reported for boa constrictors (Barker 1993, Anonymous 1997, de Vosjoli 1997, Barnes and Dillon 1998). The imperator race tends to have a darker and less distinct color pattern than does constrictor. Hogg Island boa constrictors from cays off the Atlantic coast of Honduras exhibit pale patterns that may respond to light levels. The Taboga Island boa constrictor (sabogae) in Panama has an indistinct reddish brown pattern and most likely represents an aberrant population of imperator (Langhammer 1983). Some specimens of ortonii possess wine-red blotches on the rear of the body and are called Peruvian redtails. In the Lesser Antilles, the clouded boa constrictor (nebulosa) of Dominica has many narrow obscure dark blotches on a dusky ground color, while the St. Lucia boa constrictor (orophias) simply has a higher blotch count than does the mainland constrictor. Some individuals of constrictor from the Guianas and northeastern Brazil have wine-red blotches similar to those in some Peruvian boas and represent the other major group of redtails. The Argentine or pampas boa constrictor (occidentalis) is a small dark boa with the blotches forming a
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reticulate pattern. The Brazilian or Amaral's boa constrictor (amarali) in southern Brazil and Bolivia is virtually identical to constrictor, but it has a few more dorsal spots that differ slightly in shape from those in constrictor. TABLE 1. DISTRIBUTION AND DORSAL PATTERN OF SUBSPECIES OF BOA CONSTRICTOR. Subspecific range and pattern information on Boa constrictor extracted from Boulenger (1893), Stull (1935), Lazell (1964), Stimson (1969), Peters and Orejas-Miranda (1970), Schwartz and Thomas (1975), do Amaral (1977), Vanzolini et al. (1980), Langhammer (1983), and Price and Russo (1991). SUBSPECIES amarali - Amaral's (or Brazilian or Bolivian ) boa constrictor constrictor common boa constrictor imperator Mexican or Central American boa constrictor longicauda long-tailed boa constrictor melanogaster black-bellied boa constrictor nebulosa - clouded or Dominica boa constrictor occidentalis Argentine or pampas boa constrictor orophias - St. Lucia boa constrictor ortonii - Peruvian boa constrictor sabogae - Taboga Island boa constrictor GEOGRAPHIC RANGE S and SE Brazil, SE Bolivia. Amazonian South America to Argentina and Paraguay; Trinidad, Tobago. N Mexico to NW South America; W of Andes in Colombia, Ecuador, and N Peru. Tumbes Province, Peru. PATTERN CHARACTERISTICS Middorsal head stripe without lateral projections, black rings around dorsal spots separated from one another, midbody spots with vertebral extensions directed toward head and tail, more than 21 saddle-shaped dorsal spots on body. Middorsal head stripe without lateral projections, black rings around dorsal spots separated from one another, 14 to 22 subrectangular dorsal spots on body. Middorsal head stripe with lateral projections, black rings around dorsal spots separated from one another, 22 to 30 dorsal spots on body. Middorsal head stripe with lateral projections, black rings around dorsal spots separated from one another, 19 to 21 dorsal spots on body, anerythristic dark coloration, tail length greater than 12% of total length in males. Black rings around dorsal spots separated from one another, 20 to 21 dorsal spots on body, venter black in adults. Middorsal head stripe without lateral projections, 31 to 35 obscure irregular transverse dorsal markings on clouded grey-brown ground of body. Middorsal head stripe without lateral projections, black rings around dorsal spots in contact with one another. Middorsal head stripe without lateral projections, black rings around dorsal spots separated from one another, 27 to 31 saddle-shaped dorsal spots on body. Dorsal pattern inconspicuous, color pale and sandy. Dorsal pattern inconspicuous, color dark reddish brown.

E Ecuador.

Dominica, Lesser Antilles.

NW Argentina and Paraguay.

St. Lucia, Lesser Antilles. NW coastal Peru. Taboga Island, Panama.

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TABLE 2. Subspecies

MERISTICS OF SUBSPECIES OF BOA CONSTRICTOR. Ventral Caudal Plates Plates 43-52 43-62 47-70 50-67 45-54 45 55-69 46-59 49-70 Midbody LoriSupra- Circum- InterDorsal Scale Labial References Labials Orbitals Oculars Spots Rows Rows 71-79 20-24 15-20 1 >21 35,52,65 77-95 20-25 16-20 16-22 2-3 14-22 8,15,27,35,36,52,56,65 55-79 17-23 14-20 13-16 1-2 22-30 8,12,25,35,61,63,64,65,70,72 60-76 19-21 54 86-94 20-21 35 59-69 19-21 31-35 35,36 64-87 21-22 16-20 13-16 2-3 22-30 8,35,53 65-75 14-19 16-18 1-2 25-31 8,35,36 57-72 19 19 1 15-19 11,35,54,58 65-67 -----2,35,65

amarali 226-237 constrictor 231-250 imperator 225-260 longicauda 223-247 melanogaster 237-252 nebulosa 258-273 occidentalis 242-251 orophias 258-288 ortonii 246-252 sabogae 241-247

FIGURE 1. RANGE MAP OF BOA CONSTRICTOR SUBSPECIES AND OTHER NEW WORLD BOIDS (MODIFIED FROM SAVAGE 1966). Savage (1966) recognizes three groups of New World boid genera: Young Northern (Charina, Lichanura), Middle American (Boa, Loxocemus, Ungaliophis), and South American (Corallus, Epicrates, Eunectes, Trachyboa, Tropidophis, Xenoboa). The range of the ten boa constrictor races encompasses the distributions of all Middle and South American genera except for the Caribbean forms. Boa constrictors occur from northern Argentina to northern Mexico. I started with one female imperator from the Gulf Coast of Tamaulipas Province, Mexico, and one male and one female constrictor. Hence, the young I obtain are either constrictor or constrictor-imperator intergrades. The constrictor's show the influence of imperator in some characters, so they probably were imported from Colombia or Venezuela. The female constrictor is quite dark, while the male has a light tan ground color washed with considerable pink. The imperator possesses an unusual dark red and black pattern that appears to be characteristic of the Gulf of Mexico coastal populations. Neill and Allen (1962) describe the situation for Belíze populations as follows: Elsewhere we mentioned the dark coloration of lowland boas, especially coastal ones, in British Honduras. We have since obtained 2 examples of a red phase from the mangrove swamps at Belíze. In these, all the darker elements of the pattern are dark red or cinnamon, and the background is pinkish. The specimens accord with the suggestion that reptiles from supratidal situations tend to be either unusually dark or reddish.
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Photo 1. Boa constrictor imperator from coastal Tamaulipas, Mexico.

Photo 2. Two-year-old Boa constrictor constrictor born in captivity. Natural History Ranging from the pampas of western Argentina to both northern coasts of Mexico (Figure 1), the boa constrictor probably represents the commonest, widest ranging snake in the Western Hemisphere, if not the world. This heavy-bodied species primarily inhabits lowland tropical rainforest, but also occurs in arid pampas grasslands and scrub, mountainous tropical rainforest, coastal scrubs and marshes, thorn scrubs in the Yucatan, and second-growth forests on Caribbean islands and elsewhere in the range. The cryptic color pattern corresponds to a sit-and-wait style of predation and includes fine striping through the eye and its pupil to obscure the eye's outline. de Vosjoli (1998) observed a juvenile boa constrictor twitch its tail in an attempt to lure a lizard housed in an adjacent cage. Boa constrictors feed mostly on birds and mammals, but have been reported to take lizards also (Greene 1983). Body temperature of a free-ranging telemetered boa constrictor in Mexico averaged 26.4°C (79.5°F) with a range of 24 to 38.5°C (75.2 to 101.3°F) (McGinnis and Moore 1969), while another individual investigated in Panama maintained a body temperature from 24.4 to 29.4°C (75.9 to 84.9°F) over twelve days (Montgomery and Rand 1978). Basking temperatures of wild boa constrictors vary from 26 to 34°C (79 to 93°C) (Brattstrom 1965, Myres and Eells 1968). Boa constrictors range from 40 to 55 cm (16 to 22 in.) at birth and can grow to one meter (39 in.) in the first year, one and a half (five feet) in the second, two (six and a half feet) in the third, and two and a half meters (over eight feet, females only) in the fourth year. Maturity typically does not occur until at least four years of age. Growth rate depends greatly upon the surrounding temperature and the amount of food given. Though literature reports of 4 to 5.5 m (13 to 18 ft.) exist (Greene 1983), average size attained in most populations and in captivity is considerably less. For the probable Colombians in this colony, females reach average maximum sizes of 2.4 m (94 in.) and 10.4 kg (23 lb.), while males average 1.9 m (75 in.) and 5 kb (11 lb.) (Figures 3 and 4). A mature imperator female from northern Mexico only reached 1.9 m (74 in.) and 5.4 kg (12 lb.). Growth virtually stops by the third year in males and the fifth year in females. The Growth section provides more detailed biometric data. Maximum size may vary geographically with smaller boa constrictors occurring in northern Mexico and Argentina, while larger ones are found in Amazonian South America. The length-weight relationship for colony animals estimates that an 18-foot boa would weigh better than 300 lbs. The only other large boids with such heavyset bodies are the green anaconda and blood python. Maximum lifespan reported in
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the literature is at least forty years (Bowler 1977, Huff 1980). The oldest individuals in this colony have reached the low twenties. Literature information on boa constrictor reproduction is spotty and largely anecdotal. The mating period extends from December to March in Trinidad (Mole and Ulrich 1894, Mole 1924). Females ovulate large 2-3 inch yolked eggs. "Placentation" occurs in boa constrictors and represents a process by which oxygen, carbon dioxide, water, and perhaps other small molecules are exchanged between the maternal and neonatal blood streams. The energy used for development probably comes exclusively from the yolk sac. Gestation appears to last from five to six months in Colombia (Otero de la Espriella 1978). Litters have been obtained during August in Belíze (N=2, Neill 1962) and from November to February in Peru (N=4, Dixon and Soini 1986). The reproductive cycle may vary geographically. Six Mexican and Central American boa constrictor litters averaged 17.8 young with a range of 10 to 36, while six South American (Trinidad and Peru) litters had a mean of 30.3 and range from 6 to 63 (Fitch 1985). Otero de la Espriella (1978) gives a range of 40 to 80 young per litter in Colombia. The higher mean litter size in South America may reflect variation in size of the reported females. Hoover (1936) described a Central American female that gave birth to two live young and 13 leathery "eggs," two of which produced viable young. Boa constrictors may often produce infertile eggs with solid yolks or eggs with partially or fully developed stillborn young. The membrane of such eggs usually becomes thickened, translucent, and tough compared to the clear, delicate membrane containing a viable neonate. Use by Man The boa constrictor today represents one of the most heavily exploited reptile species. Dodd (1986, 1987) reports on legal importation of snakes into the United States. From 1977 to 1983, over 113000 live boas were imported; this amounted to nearly half of all the imported snakes listed for protection by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Live imports decreased 97 percent from 1979 to 1983 as more animals were used for production of ornamental leather. In 1983, 6572 whole boa constrictor skins, 1714 large leather pieces such as briefcases, and 165843 small pieces, mostly shoes, were brought into the United States. The only other snake species that supplies more skins and leather is the reticulated python (Python reticulatus). Though Otero de la Espriella (1978) describes a culture operation for boa constrictors in Colombia, the vast majority of imports must arise from natural populations whose status is completely unknown. HERPETOCULTURE Temperament and Handling Boa constrictors tend to be very easy-going snakes. Disposition varies among individuals, between races (imperator's have a nasty reputation), with age, and in response to handling. If a boa constrictor is in a bad mood, the head and neck usually are thrown back in an S-curve and the animal may hiss long and very loudly. It is not hard to tell when a boa constrictor wishes to be left alone. After biting, the snake may let go immediately or clamp down with its jaws and coil tightly around anything available, including arms and legs. Holding the animal's head under a running tap may convince it to release its hold. Otherwise, a flat card or blade must be forced between one of the jaws and whatever it is biting. At this point, the other jaw can be unhooked. Boa constrictors seem to become more familiar with people as a result of handling and so are less likely to bite if taken out of their cages every now and then. All of the young which I have raised can be handled freely. My boa constrictors have bitten me in two situations. One is during or just after feeding, and the second is during their "adolescence." Tongs for holding the food item help greatly in avoiding mistakes on the snake's part during feeding. Handling the snake after feeding is not recommended, since it is prone to bite and also may regurgitate. Putting your hand in front of a boa constrictor after you have been holding food is asking for trouble. Boa constrictors feed very reliably and initially seize prey on the basis of smell rather than vision. Thereafter, their sense of smell seems to be swamped and they may bite anything that moves suddenly in their vicinity. Further details on feeding are given below. I have noticed that one to one and a half meter (three to five feet) boa constrictors sometimes become nervous when handled. They also may bite lightly if touched suddenly on the body. These bites may startle you, but are not serious and do not hurt much at all (though you will bleed a bit). They can be avoided by handling the snake in a gentle manner without any sudden moves on your part. In general, boa constrictors should be supported fully and allowed to wrap around your hands and arms. They fear situations where they
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might fall. Holding an animal around the body at an arm's length definitely tends to make it feel insecure. In any event, this proclivity to biting seems to be part of an "adolescent" stage that the snake will grow out of. Bites of boa constrictors less than one and a half meters (five feet) generally have the severity of a cat scratch, but those from larger boas can require a few stitches if the skin tears when the person or snake pull back. If you feel apprehensive about the size and/or temperament of your snake, you should sell it and get a smaller and/or nicer one. Housing (Vivarium Research Group, Inc. 1998) Cages or aquaria made with wood, plastic, fiberglass, glass, etc. serve well for boa constrictors. No screen should be used for the top or anywhere else in the cage. Using screen in the cage is a common mistake. Some individuals will rub their noses on screen or other rough surfaces until they develop abrasions and infections (see mouth rot under Health), will not feed, and starve to death. Even if the snake recovers, the disfigurement will be permanent since the scales will not grow back. Sometimes the abrasions can even cause fatty tumors (see Photo 3 below) to develop. Snakes can be remarkably quick in rubbing their snouts raw, say several hours. I recommend pegboard for tops as it is readily available, cheap, and easy to work with. Since snakes require very little air circulation, cages can be closed off to make them easier to heat (which is a great deal more important for tropical snakes like boa constrictors). Cages should be large enough for the snake to stretch out in, if possible. Large animals should be kept in cages with a long dimension at least two thirds of the snake's length. Though boa constrictors like to climb, floor area is more important than height in a cage, particularly for large individuals. Much controversy exists over what to put in the cage besides the snake. The following is my personal preference. In general, I like to keep the interior of the cage as simple as possible, since it facilitates cleaning, changing water, and taking the snake out of the cage. Naturalistic tropical vivaria can be used for small boa constrictors (Vivarium Research Group, Inc. 1998). Careful consideration should be given to rocks, branches, and such that are placed in the cage as the inhabitant's safety depends upon it. Boa constrictors are not bright nor are they adapted to living in cages. As a consequence, they potentially can get caught in rock holes or branch forks that can cause injury or death. Movement through tight spots also can scar the boa when done during the shedding period. Photo 3. Fatty tumor that probably resulted from Many people use newspaper, cedar shavings, Astro-Turf, abrasions caused by rubbing the snout on screen. dirt, sand, etc. in the bottom of the cage: I recommend pine These tumors typically float more or less freely under shavings. Some boa constrictors, particularly small ones, like to the skin and can be removed easily. However, they burrow, and pine shavings are the only substrate other than cedar usually are not dangerous from a health standpoint shavings that allow them to do this. A depth double the diameter unless they begin to invade the eye or nose areas and of the snake suffices for burrowing. Aside from being more interfere with shedding, breathing, or feeding. Of expensive than pine shavings, cedar shavings are too aromatic course, most people do not find them very and some people assert that they are detrimental to the health of aesthetically pleasing. snakes. Pine shavings are absorbent and dry out quickly. A damp cage leads to scale mite population explosions and blister disease (see under Health, Wright 1995). Feces and surrounding shavings can be easily removed and replaced with fresh bedding. Spot cleaning should be carried out at least once a week. All bedding should be replaced and the cage cleaned thoroughly at least twice annually. The one disadvantage of shavings is that snakes can accidentally ingest them while feeding; see Food and Water for further discussion of this problem. Many ranch and feed stores carry bale-size packages of pine shavings for around ten dollars. Placing a layer of plastic sheeting in the bottom of a wooden cage will prevent water and other fluids from wetting the lumber and causing irremovable odors. The plastic must be firmly attached to the cage with no holes or free edges; otherwise, a boa constrictor may be depended upon to get under it. Boric acid power can be sprinkled beneath the plastic to control mites, ants, and other arthropod pests. Since boa constrictors are tropical poikilotherms, their cages must be heated. Otherwise, they develop colds and pneumonia, have trouble with digesting food, may regurgitate after eating, and become more susceptible to many diseases and pests, in particular amoebiasis, blister disease, and scale mite infestations (see under Health). Individuals will form aggregations in captivity, evidently in order to retain heat (Myres and Eells 1968). Particularly while digesting food, boas attempt to maintain a temperature from 31 to 32°C (88 to
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90°F) (Regal 1966, Myres and Eells 1968). Wild caught boa constrictors should be maintained above 27°C (81°F), but my captive-born animals do well at temperatures as low as 24°C (75°F). Some kind of localized heat source should also be present, so the snake can achieve a temperature appropriate for digestion. If the room cannot be maintained at a temperature higher than 24°C (75°F), supplemental heat must be provided for the cage. Hot rocks are made of plaster with an embedded electric heating element and work well in a small cage if they can be obtained. Heating pads that are placed in the bottom of the cage can get wet and sometimes do not provide sufficient heat. Subfloor heating with light bulbs, heater tape or ribbon, or heating pads may work in some situations. An incandescent light or space heater near the cage are also viable solutions. Incandescent lights and other filament heaters can be wired to a transformer or light dimmer to control their heat output (Logan 1972). Care must be taken to avoid cracking glass or overheating the cage with the heat source. An aquarium heater or incandescent reflector may be used inside the cage, but it should be suitably isolated so the boa cannot touch it and burn itself. Light reflectors used within a cage should be set up so that no hot areas, wires, or sharp edges are exposed. Whatever heating option is selected, the temperature should be checked every few days to confirm that an appropriate temperature range is being maintained. Boa constrictors quickly develop colds and their susceptibility to other diseases also increases at low temperatures. Boa constrictors also require high relative humidity, preferably around 70 to 80%. This can be a real problem in the winter when heating the cage drops the humidity. Boas often have problems with shedding and may develop blister disease if the humidity is too low (see under Health). The most direct way to raise the humidity is to spray the boa and its cage every day or two. Care must be taken so the cage does not become excessively damp, as this condition will encourage scale mite infestations and blister disease. The presence of plants in the cage or use of a humidifier may also help. Food and Water One advantage of a boa constrictor as a pet is that it can go without food and water for weeks, thus freeing its owner for fairly extended trips. The concomitant disadvantage is that snakes will not beg for food as a cat or dog will, so many owners neglect the snake's feeding. In combination with their elongated morphology and the difficulty of recognizing that the animal is indeed becoming thin, this results in many captive snakes getting so weak that they can no longer feed. For these and other reasons, starvation is probably the most common cause of death in captive snakes (see under Health). Water should be present in the cage at least a few days out of the week. Boas like very much to soak in water on occasion, so the container should be large enough to hold snake and water without overflow. I keep water containers a third to half full. Large boas will tip over containers, unless they are heavy or are fastened in place. Water should be changed once or twice a week or whenever feces are deposited in it. Considerable latitude exists in food item size, amount of food per feeding, and frequency of feeding for snakes. Table 3 provides a rough guide for boa constrictors of different sizes. Overall amount of food eaten can vary easily from one half to twice as much as indicated in the table. Amount of food given will depend upon temperature and how high a growth rate is desired. Boa constrictors typically eat much less in winter than in summer. TABLE 3. FEEDING SCHEDULE. Size and Type of Food Item Frequency of Feeding baby to 3-week-old rats, mice 1 mouse per week 3-week-old rats, mice 2-4 mice per week half-grown rats, chicks 2 rats per week rats, 1-month-old chickens 2 rats per week rats, half-grown chickens 3-4 rats every two weeks rats, chickens, rabbits 1 rabbit every 3 weeks

LENGTH OF BOA 40-60 cm (16-24 in) 0.6-1 m (2-3.3 ft) 1-1.5 m (3.3-4.9 ft) 1.5-2 m (4.9-6.6 ft) 2-2.5 m (6.6-8.2 ft) 2.5 m (8.2 ft) or more

Since boa constrictors feed very readily, some precautions are necessary, particularly if more than one animal are present. It is best to separate individuals to different containers, since they will attempt to seize anything that moves nearby when they are feeding and will also try to bite and constrict food that another snake already has. Heavy leather or rubber gloves that extend to the elbows are useful for handling large boa constrictors during feeding sessions. Boa constrictors feed so readily (and sloppily) that they sometimes engulf shavings, gravel, or other indigestible materials as well as the food. The snake may not be able to pass or
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regurgitate the foreign matter if it is large enough relative to the animal's size. These items can cause stomach ulcers that will kill the snake. The only sure way to avoid this problem is to feed the boa constrictor in a container having only the snake and food present. Any aquarium or plastic box will serve for small boa constrictors, but styrofoam boxes are the cheapest and most handleable alternative for large individuals. I recommend that only animals that already have been killed be given to boa constrictors. The most important reason for this is to prevent injury to the snake as a result of bites or scratches from the prey (Klingenberg 1998). Fry (1973), a veterinarian with extensive experience in reptile treatment, states that the most common traumatic lesions he deals with in snakes are rat bites in boa constrictors. Deaths rarely result from these bites, but permanent scars do since destruction of underlying soft tissues usually occurs. Killing the food animal beforehand is also more humane for the prey. Boa constrictors do not care whether the animal they are eating is alive or dead; they usually constrict it as if it were alive. Food items can be offered to a boa constrictor with tongs, by dropping the food into the snake's container, or by leaving the food in its cage. Shavings should be swept clear of the area in the cage where feeding takes place. If a boa constrictor refuses to eat, it is either too cold, already full, frightened, shedding, sick, or pregnant. Full, shedding, and pregnant boa constrictors should not be fed, cold boas should be kept warmer, frightened individuals may have to be left with their food overnight, and sick animals may require treatment or force-feeding (see under Health). Live food should never be left with a snake, unless the situation is kept under observation. Rats and mice can and will chew patches of skin off of a snake (Klingenberg 1998). Newborn boas have a substantial amount of yolk in the gut and spend their initial one to two weeks shedding. They should never be fed until after their natal shed, as doing so increases the risk of amoebiasis or other intestinal infections (see under Health). Since boa constrictors readily will accept dead animals, it is often convenient to obtain a large amount of food, kill and freeze it, and defrost suitable portions at the time of future feeding sessions. The food only needs to be at room temperature. The method of choice for euthanasia is carbon dioxide asphyxiation with cervical dislocation as an alternative. Freezing destroys parasites which might be passed on to the snake, but it may also be deleterious for vitamins. I doubt that this is true, since I have fed frozen animals to captive born boa constrictors for years, and the snakes exhibit normal growth and no overt vitamin deficiencies. For whatever reason, if a snake should refuse to eat, the food should always be discarded and never refrozen. The convenience of frozen food is another strong reason for giving boa constrictors dead animals to eat. Snake food may be obtained from a variety of places. Pet shops carry rats and mice. Ranch and feed stores often stock chicks, chickens, and rabbits. These animals also are advertised in the classified section of newspapers, though they may be intended as pets. I do not recommend succumbing to the temptation of obtaining animals such as puppies or rabbits that are being advertised only as pets. Laboratories sometimes get rid of large numbers of research animals and do not mind if they are used to feed snakes. Experimental animals from laboratories should be free of toxic substances and should not have been killed with ether, phencyclidine (Sernalyn), sodium pentobarbital (Nembutal), or other barbiturates. Using animals with questionable origins or edibility is not worth the risk. Wild animals should be avoided Figure 2 Weight-Length Relationship of Boa as a source of food. The need for snake food will not justify the Constrictors in Colony expense and effort required to maintain a rodent colony, rabbit ln [Weight (lb)] = 3.216 ln [Total Length (ft)] -0.5065 hutch, or chicken coop. However, if excess animals are ln [Weight (kg)] = 3.216 ln [Total Length (m)] - 3.537 available from one of these sources, they can be fed directly to Weight (lb) = 0.0291 [Total Length (ft)] 3.216 a snake or frozen for later use. Weight (kg) = 0.6026 [Total Length (m)] 3.216 Growth Like most animals, boa constrictors have a cubic lengthweight relationship. Figure 2 is based on 360 observed weights for snakes of different lengths in English units. Note that the length and weight axes have logarithmic scales with linear numeric labels. The equations were derived from data on 81 newborn and 15 older boas that ranged from 1.3 to 8.3 feet (0.41 to 2.53 meters) in length and from 0.062 to 30.5 pounds (0.028 to 13.84 kilograms) in weight. Multiple measurements were taken on specimens that had grown substantially. Boas were measured and weighed just prior to being fed. Intermediate values can be determined by working through one of the equations with any calculator having logarithm and
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exponentiation functions. The natural logarithm formulae can be converted to base ten logarithm versions by dividing the intercepts (-0.5065 or -3.537) by 2.3. Alternatively, the graph itself can be used to obtain a direct estimate of weight for a particular length. Since length "explains" 99 percent of the variation in weight, the relationship of length and weight is very tight. The standard deviation of weight about the regression line amounts to about fifteen percent of the weight predicted for a particular length, so the predicted weight plus or minus fifteen percent is an appropriate range to maintain an animal's weight within. If a boa constrictor weighs less than two standard deviations (thirty percent) below the weight calculated for its length, more feeding is required. Conversely, if the snake is thirty percent or more heavier than its predicted weight, it is too obese. It should be noted that the weight data for the above regression relationship were obtained for snakes just before feeding. A boa constrictor easily can eat without harm up to a quarter of its body weight during a feeding session.
Figure 3 GROWTH IN LENGTH THROUGH TIME. Figure 4 GROWTH IN WEIGHT THROUGH TIME.

Growth rates over time are a great deal messier than the length-weight relationship, since growth is affected strongly by temperature, amount of food, sex of the boa constrictor, and probably the snake's area of origin. Figures 3 and 4 show age isoclines based on seven females and four males whose age is either known or can be estimated closely. The graphs show that the highest growth rates occur in the first three or four years of life. After this, males appear to approach a maximum of about 75 inches (191 centimeters) and eleven pounds (five kilograms). Females continue to grow to much larger sizes, and their data points indicate that a maximum has not been reached by sixteen years of age. The data include a ten-year-old imperator female that measures around six feet (two meters), weighs about nine pounds (four kilograms), and comes from Mexico, an area where individuals may attain a smaller maximum size than do the constrictor's of South America. Reproduction Only a spotty and somewhat puzzling literature on reproduction in boa constrictors currently exists. This is particularly surprising, since the species is an abundant, widely occurring snake that is often bred in captivity. Males may be distinguished from females by their greater development of the "spurs," proportionately longer and fatter tails, and higher numbers of caudal plates (Table 4, Figures 5 and 6). Data on the true sex were obtained by dissection, spur development, or breeding. "N" indicates neonates and "N*" denotes constrictor-imperator intergrade neonates in the Figures. Newborns can be sexed by a technique used for small boids. The technique involves catching the base of the tail between the thumb tip and index finger, applying light pressure, and pulling the tail through the opening. In males, blood seems to get caught in the hemipenes within the tail and the heads of the hemipenes can be palpated as they pass beneath the thumb tip. Eversion of the hemipenes or probing is unnecessary in sexing boa constrictors. Both approaches also seem to be inaccurate and potentially dangerous to the animal. TABLE 4. SEXUAL DIMORPHISM IN BOA CONSTRICTORS. 4.1. Literature Records of Caudal Plate Numbers in Males and Females. SUBSPECIES Males Females REFERENCES constrictor 52 - 58 43 - 59 15,27 imperator 55 - 70 48 - 61 61,63,64

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4.2.

Caudal Plate Numbers of Males and Females in the Colony. Sex N Mean Std. Dev. Range 95% Confidence Interval Male 13 57.85 2.91 54 – 64 56.26 - 59.43 Female 17 50.76 1.68 47 – 53 49.97 - 51.56

4.3.

Tail Length as a Percentage of Total Length for Males and Females in the Colony. Sex N Mean Std. Dev. Range 95% Confidence Interval Male 17 11.55% 0.99% 9.76 - 13.68% 11.08 - 12.02% Female 20 9.85% 0.63% 8.70 - 10.64% 9.58 - 10.13%

Figure 5 Caudal Plate Numbers for Males and Females in the Colony.

Figure 6 Tail Length as a Proportion of Total Length for Males and Females in the Colony.

Males do not show aggression toward one another, though they do have typical boid courtship behavior involving topping and titillation of the females with their spurs. I keep pairs together throughout the year and have never used male combat as a stimulus for mating. Colony males have never needed any encouragement to court. Individuals in my colony reproduce under the natural diurnal cycle observed at about 30° Latitude N. I have never purposely cooled my boa constrictors in the Fall, though their ambient temperature does drop from the 28-34°C (82-93°F) range to 25-29°C (77 to 84°F). My animals breed annually from August to March with a peak in January, nearly the same as the December to March mating period observed in Trinidad (Mole and Ulrich 1894, Mole, 1924). My impression is that females require relatively high body weight to assure ovulation. Reproductive females accumulate huge abdominal fat bodies in the latter third of their bodies that can increase their normal body weight 25 to 30%. Owners often mistake this fat accumulation for pregnancy and then assume the eggs are "reabsorbed" when no birth occurs. Egg resorption is known only in certain mammals such as people. Resorption can only take place in animals with small eggs, not in those groups with large yolks like reptiles and birds. In boa constrictors, the presumed resorption only involves the slow utilization of the accumulated fat bodies when ovulation fails to occur. Soon before or after a female mates, I have noticed a large localized swelling three-fifths of the way down the body that lasts several days and marks the time immediately before ovulation (see Photo 4 below). Since this happens only during a restricted time when the female is receptive, it probably results from yolking and/or aggregation of the eggs prior to ovulation. This phenomenon also has been noted in various other pythons, boas, and even some colubrids (Van Mierop and Bessett 1981, Barker and Barker 1995). It probably provides the best indicator of the start of gestation. Egg yolking evidently occurs very quickly in birds and reptiles (chickens do it in nine days). Up to sixty 2 to 3 inch eggs may by yolked in the boa constrictor's ovaries during this short period. The large fat bodies serve as the source for yolk production.

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11 Figure 7 Period of Gestation from Time of Ovulation to Partruition for Six Pregnancies in the Colony.

Photo 4. Midbody swelling in an ovulating boa constrictor.

Photo 5. Copulation in boa constrictors. Five females in my collection have given birth from 119 to 133 days after swelling of the midbody was observed (Figure 7). Actual mating serves as a poor indicator of the beginning of pregnancy, since ovulation may not happen simultaneously with mating or at all. Boa constrictors generally have their young four and a half to six months after copulation, as has been reported from a commercial culture operation in Colombia (Otero de la Espriella 1978) and for constrictor and imperator females that have mated in captivity in Switzerland (Gensch 1969, Meyer-Holzapfel 1969). Mated females probably store sperm in the two uterine horns. Females eat little or nothing during the last half of pregnancy. Pregnant females may remain tightly coiled and thermoregulate at 27 to 32°C (80 to 90°F) (see Photo 6 below). Pregnant boa constrictors should be maintained at 28 to 34°C (82 to 93°F). Extreme temperatures for even a short time during pregnancy can cause deformities, primarily in the caudal region. Stillbirths and unfertilized or partially developed ova are not uncommon, especially in initial, low temperature, or disturbed pregnancies.

Photo 6. Late-term pregnancy in a thermoregulating boa constrictor.

Photo 7. 40 baby B.c. constrictor. What you finally get 5 months after ovulation.

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Litters have been obtained during August in Belíze (Neill 1962), from November to February in Peru (Dixon and Soini 1986), and in June and July from imperator and constrictor females that mated in captivity in Switzerland (Gensch 1969, Meyer-Holzapfel 1969). Females in my colony have given birth from February to August with a tendency toward May and June (Figures 7 and 8). This only leaves September and October. The reproductive cycle may vary both geographically and in response to conditions of captivity. Live births in my colony have numbered from four (in a constrictor-imperator cross) to forty- Photo 8. These twins have a common yolk sac and nine with a mean of 31.3 per litter in fifteen pregnancies. Litters “placenta.” Developmental (probably mechanical) from pregnancies with no complications have yielded from problems have prevented the usual transfer of yolk to sixteen live births and one infertile egg to forty-nine live births the babies and have caused them to be significantly and six stillbirths or infertile eggs. All of the litters in my colony smaller than the usual neonate. Though these two have included at least a few eggs resulting from unfertilized ova conceivably could be fraternal twins with fused or embryos that die during development. Examination of these yolks, their high pattern concordance suggests that eggs has always revealed solid yolk or dead embryos or fetuses. they are identical. No obvious birth defects other One set of identical twins (see Photo 8 at right) has been than small size were present, but they were poor identified in approximately 600 births. This pair had a common feeders and died several months later. Other yolk sac and extremely high pattern concordance. Live births neonates with large yolks usually die as well. have comprised 60% (469 out of 776) of the total production of Figure 8 Numbers of Live Births and Other Eggs eggs in this colony (Figure 8). (Unfertilized Ova or Stillbirths) Produced in the Many problems can accompany pregnancy. Four Colony. unsuccessful pregnancies, due either to genetic incompatibility or premature termination, and one in which twenty-eight unfertilized eggs were produced, have also occurred in my colony. Low temperature and other adverse prenatal conditions contribute to congenital defects that include eye hydrocele, scoliosis, prolapsed hemipenes, cleft palate, incomplete umbilical closure, and spina bifida. Newborns normally measure 46 to 56 cm (18 to 22 in.) in length, but may be considerably smaller if the six inch umbilicus twists and prevents transfer of yolk to the developing boa constrictor. Structural twisting of an oviduct can prevent the passage of young and eggs from both horns anterior to the block. Retained eggs and young encyst, but can be removed surgically (see Photo 9 below). Feeding a large meal to a pregnant female can cause her to abort. An obviously pregnant female should be fed lightly or not at all.

Photo 9. Surgical removal of uterine horns with retained ova.

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Photo 10. Uterine horns with retained eggs. Closeup of oviducal torsion preventing passage of the ova. This boa survived for about a year after the operation. Health Very little therapeutic knowledge exists for diseases of reptiles and many medicines known to be effective in treatment are not generally available, so the key to keeping a boa constrictor healthy is prevention. A captive-born animal is advantageous in that one starts off with a clean slate, but they are nevertheless subject to a wide range of ailments. The discussion below covers most commonly encountered problems. Hoff et al. (1984) have presented a recent comprehensive review of reptilian diseases. Frye (1973) provides an excellent practical guide to medical treatment of captive reptiles. Colds Since they are tropical animals, boa constrictors are highly susceptible to colds. Symptoms are mostly as in people: lethargy, depressed appetite, labored open-mouth breathing, wheezing, congestion, and oral discharge. Simply raising the temperature to the 27 to 30°C (81 to 86°F) range solves the problem. My two wild caught constrictors, like myself, often developed sporadic colds during the winter. However, the imperator from Mexico and all of the captive-born individuals never catch colds, even when kept around 24°C (75°F). Place of origin and amount of acclimation apparently play a part in determining degree of susceptibility to colds. Pneumonia Pneumonia is very serious and requires treatment with antibiotics. An infected animal exhibits extremely severe cold symptoms and will be too weak to shed or eat. It should be isolated immediately and given intramuscular injections of ampicillin trihydrate (Polyflex, 3-6 mg/kg), oxytetracycline HCl (Liquamycin, 6-10 mg/kg), or chloramphenicol (Chloromycetin, 10-15 mg/kg) once a day (Frye 1973). Murphy (1973) has reported that tylosin is extremely effective for respiratory problems in a wide variety of reptiles. It is administered in a daily 25 mg/kg dose as either an oral solution (Tylan) or intramuscular injection (Tylocine) for seven days. Well stocked ranch and feed stores generally carry both Liquamycin and Tylan. Force-feeding as described below under Starvation may be required. Snakes that are kept warm and well fed will not contract pneumonia. Mouth Rot (Stomatitis) Mouth rot can be disfiguring and, if it leads to starvation, lethal. The oral mucosa presents a cottony appearance and swells till the animal cannot fully close its mouth. This bacterial infection (Aeromonas, Pseudomonas, Pasteurella) is treated effectively by swabbing the oral cavity twice a day with mild antiseptic solutions such as Listerine, 3% hydrogen peroxide, thimerosal (Merthiolate), benzalkonium chloride, or Betadine (Frye 1973, Marcus 1980). Severe cases may require antibiotics. Force-feeding as described below may be necessary if the condition has progressed far enough. Mouth rot is prevented easily by proper cage construction and hygiene (see under Housing).

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Starvation (Inanition) Starvation is usually a secondary effect of another disease but frequently the primary cause of death. A thin snake will be lethargic and weak. An emaciated snake will exhibit prominent bones, sunken eyes, and a shriveled skin as well. Curing the disease and force-feeding, if necessary, comprise the treatment. Diluted and beaten egg yolk mixed with canned cat food or a commercial nutritional replacement product such as PetKalorie or Nutrical (Frye 1973) is tube fed to the snake to gain back or maintain body weight. A flexible tube attached to a syringe filled with food is passed down the esophagus and the food is then injected into the stomach. Force-feeding small food items to a sick snake is a last resort. The food should be lubricated with beaten egg yolk and pushed down the throat with a flexible blunt probe. Injuring the snake's cervical vertebra is easy to do when force-feeding. Sometimes a nonfeeding animal will complete eating unassisted if the food item simply is pushed into its mouth. Inclusion Body Disease (Schumacher et al. 1994; Klingenberg 1996, 1997a, 1997b) This viral disease has only recently been characterized and little is known about it. Clinical symptoms include poor condition, weight loss, anorexia, regurgitation, chronic secondary infections, and neurological problems such as tremors and stargazing. Many other reptile diseases also can cause these symptoms, but inclusion body disease appears to be much more common in collections than previously hoped. The pathogen is thought to be a retrovirus that is transmitted primarily by mites and ticks. Diagnosis requires blood analysis and organ biopsy. No treatment exists for the disease. Infected animals that show symptoms can be given supportive care, but remission has never been observed. Because of the deadly nature of this disease, the lack of any effective treatment, and the high chance that it will spread to other snakes in a collection, infected individuals should be euthanized. Amoebiasis By the time amoebiasis can be diagnosed, it is usually too late to save the individual. The rear half of an infected animal's body may swell greatly, movement becomes difficult, a hard plug may form in the colon anterior to the cloaca, anorexia develops, and the snake can only pass blood-tinged mucus. The snake generally can only drag the rear half of its body around. After diagnosis, animals usually die a few days later from gastrointestinal enteritis and liver abscesses. Infected individuals should be isolated immediately, preferably to a different room. The cage must be disinfected thoroughly. Since the pathogen, Entamoeba invadens, occurs in a cyst form, it is extremely infectious and can be transported in bedding or on the hands. Amoebiasis is the worst infectious disease of herpetological collections (Donaldson et al. 1975, Bihn and Napolitano 1980). Metronidazole (Flagyl) is given orally at a dosage of 250 mg/kg (Donaldson et al. 1975, Napolitano et al. 1979). Another drug that has been used is emetine HCl as a daily 0.5 mg/kg intramuscular injection for ten days (Frye 1973, Napolitano et al. 1979). High temperatures in the 35 to 37°C (95 to 99°F) range evidently cause Entamoeba invadens infections to die out (Barrow and Stockton 1960; Meerovitch 1960, 1961; Bihn and Napolitano 1980). Control and eradication of infection may be possible by holding animals at this temperature range for one to two days. Conversely, quick drops in temperature to around 25°C (77°F) such as occur in the Fall, may trigger a latent infection into the full blown disease (Meerovitch 1961). Prevention requires avoidance of crowded community cages with many snakes, an appropriate temperature regime, good cage hygiene, and food that is not old or refrozen. Lesions of the intestinal wall caused by ingestion of shavings or other rough indigestible matter may increase susceptibility to infection. Cryptosporidium spp. (McAllister et al. 1995) Cryptosporidium infections in reptiles have only been described in the past twenty years. Snakes become infected through oral ingestion of oocysts in the environment. As in people, reptiles may become resistant to infection or may simple tolerate the parasite. Snakes with moderate to severe cryptosporidiosis exhibit anorexia, pneumonia, gastroenteritis, lethargy, midbody swelling, weight loss, and regurgitation. No effective medicinal treatment for Cryptosporidium has been found. Oral hydration and tube feeding (see Starvation above) represent the only supportive therapeutic intervention. Cestodes, Nematodes, Trematodes, and Lingulatids These parasites usually never become a problem unless the infected animal becomes weakened for some other reason. Use of some cat or dog medicines can kill snakes. My original male constrictor regularly used to pass tapeworms, but never seemed to be bothered by them. He eventually appeared to become clear of them.
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Captive-born boa constrictors will never have tapeworms or other similar types of parasites, unless they are fed a wild-caught animal or bird that is infected, or a cross-infection occurs with a cagemate. Only domesticated animals should be used for snake food. Captive-born boa constrictors should not be kept with other snakes that may have a parasitic infestation. If a boa constrictor somehow gets internal parasites, I recommend that nothing is done unless the animal shows chronic weight loss. Zoo and veterinary personnel may be of some help for diagnosis, treatment, and medicines such as niclosamide (Yomesan, 150 mg/kg orally) or bunamidine HCl (Scolaban, 25-50 mg/kg orally) for cestodes, piperazine citrate (40-60 mg/kg orally) or thiabendazole (Thibenzole, 50 mg/kg orally) for nematodes, and emetine HCl (0.5 mg/kg/day intramuscularly for ten days) for trematodes (Frye 1973). I have also noted that snakes sometimes pass tapeworms when treated with DDVP (phosphoric acid 2,2-dichlorovinyl dimethyl ester) for mites. The standard veterinary use for DDVP turns out to be as a gastrointestinal wormer for livestock. Ranch and feed stores may stock some of these drugs. No treatment is available currently for lingulatid (tongue or lung worms of the Genus Armillifer) infestations. Mites, Ticks, and Lice Mites (Ophionyssus) and ticks (Ornithodoros and Amblyomma) are parasitic arachnids dangerous for their ability to transmit viral and bacterial pathogens. Book and wood lice (Psocoptera), however, are only nuisance insect pests. Unfortunately, keeping snakes free of mites can be like trying to keep mammals free of fleas. The ideal solution is prevention through the strict quarantine of any new incoming animals. Rubbing snakes with paraffin oil does not kill eggs in the cage and the desiccant silica-aerogel powder Dri-Die 67 has been unavailable for a long time to my knowledge. Silica-aerogel products also are reported to cause longterm pulmonary problems (Frye 1973). DDVP (phosphoric acid 2,2-dichlorovinyl dimethyl ester), better known as Vapona in No-Pest Strips and others, has been used as an airborne miticide to control mites and ticks, but reptiles and people are known to be sensitive to DDVP, a cholinesterase inhibitor with cumulative effects, and must be kept out of contact with the strips if they are used. If mites or lice get out of hand, small pieces of a pest strip can be enclosed in containers punched with holes and placed in the cage for several days. A thorough cleaning of the cage and soaking of its occupants in water should also be carried out at the end of this period. My strategy has been to keep the arthropod populations as low as possible (preferably at zero) by using pine shavings and keeping the cages clean, dry, and uncrowded. Prompt removal of feces and sheds also prevents conditions conducive to their reproduction. Rarely do I have to resort to pest strips and soaking. The presence of mites and lice can be determined most easily by examining the inner surface of a recent shed (actually the outer surface of the skin). Since they will be moving around and are whitish gray (lice) to black (mites) in color, even small mites and lice will be visible against the light background of the shed. They also turn up in the water container after an infested boa has been soaking in it. Large mites can be seen easily when they are running around on the head and other body parts of a captive snake. Some of the most impressive mite and lice populations I have ever seen were on snakes kept on damp, dirty newspaper. Large ticks usually survive exposure to DDVP and must be removed manually. Very hot forceps are the only way I have found to convince ticks to back out; yanking out ticks without heating the forceps usually leaves the mouthparts in place where they can cause infections. The wound should be treated with an antibacterial cream or solution such as Neosporin, hydrogen peroxide, thimerosal (Merthiolate), benzalkonium chloride, or Betadine. Scale Infections (Blister Disease or Vesicular Dermatitis) (Wright 1995) Bacterial or fungal scale infections result from the combined effects of high mite populations, cool temperature, and damp, dirty cage conditions. In some circumstances, low humidity can also cause this condition. The infections themselves are small upraised areas covering one or two scales. Severe infections are suppurating. In combination with the conditions causing them, the infections cause an animal to weaken, stop eating, and forego shedding. The cage must be cleaned and dried out. The snake can be soaked in a fifty percent Listerine or dilute organic iodine solutions for an hour a day. Very weak snakes must be given something to support their head out of the solution and should be monitored so they do not drown. Scarring usually does not result from scale infections. Force-feeding as described under Starvation may aid recovery in weakened snakes that refuse food. Problems with Shedding (Dysecdysis) The reason that snakes shed their skins often is said to be that shedding permits growth. This idea has arisen because they shed their skins as a single piece and the situation has been analogized with the molting of
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insects and crustaceans. Snakes actually grow in the same way as the majority of other organisms, i.e., cell division. The true reason they shed their skins is the same one that people have for shedding: to replace the outer damaged layer of the skin. The only difference is that snakes do it all at once; people and other animals tend to do it in patches (dandruff is the most visible evidence of this). Shedding frequency increases with temperature and feeding rate, since the overall metabolic rate increases. Snakes with skin injuries also usually increase shedding frequency, a response apparently associated with the healing process. Boa constrictors undergo a well defined physiological sequence when they shed their skins. The first indication is dulling of the overall pattern. The snake may refuse to feed from this point until after it has shed. Animals should not be fed or handled during the shedding period, as the skin is very soft and susceptible to injuries causing scars. Within a few days, the skin becomes quite dull and the eye spectacles assume an opaque milky appearance for a day or two. Snakes can be quite nervous during this period when they cannot see well. They often develop a proclivity for soaking in the water container at this time. The skin and spectacles then clear up. Shedding occurs three to seven days later. As mentioned before, sheds should be removed promptly to prevent mite infestations. The new skin exhibits bright vivid markings. Unhealthy snakes or those under poor cage conditions often have problems with shedding their skins. Low humidity and/or temperature can cause a boa constrictor to forego shedding its skin even though it has completed the preparatory stages. Shedding boa constrictors should be kept warm and under high humidity with daily spraying, if necessary. Recalcitrant individuals can be soaked in an appropriate container to keep the old skin from drying and adhering to the new one. Wetting of the snake and shedding by hand should be done when areas of old skin have loosened and the snake still refuses to shed on its own. Even healthy individuals occasionally have difficulties with certain areas, usually the spectacles and the tail. If patches of old skin are still adhering to the new one after a snake sheds out, removing the old skin is a fairly simple procedure. A finger moistened with water or mineral oil is rubbed over the free anterior edge of the old skin toward the tail. The old skin should come off fairly easily. Care must be taken with removing an old spectacle, since the edges of it may be adhering tightly and trauma to the underlying new spectacle and eye may occur. Very rarely, it is better just to leave the old spectacle or other unshed skin in place until the next shedding. REFERENCES 1. Anonymous. 1997. The cutting edge of herpetoculture: Boa constrictors. Vivarium 9(2): 40. 2. Barbour, T. 1906. Vertebrata from the savanna of Panama. IV. Reptilia and amphibia. [description of sabogae] Bull. Mus. Comp. Zool. 46: 226. 3. Barker, D., and T. Barker. 1995. The mechanics of python reproduction. Vivarium 6(5): 30-33. 4. Barker, D.G. 1992. Bold confidence and white boas. Vivarium 4(4): 20-22. 5. Barnes, M. and T. Dillon. 1998. Mocha boa. Vivarium 10(1): 34. 6. Barrow, J.H., and J.J. Stockton. 1960. The influences of temperature on the host-parasite relationships of several species of snakes infected with Entamoeba invadens. J. Protozool. 7: 377-383. 7. Bihn, J.P., and R.L. Napolitano. 1980. Protozoa of reptiles and amphibians. Pp. 243-248 in Murphy, J.B., and J.T. Collins. Eds. 1980. SSAR Contributions to Herpetology Number 1: Reproductive Biology and Diseases of Captive Reptiles. Lawrence, Kansas: Society for the Study of Amphibians and Reptiles. 277 pp. 8. Boulenger, G.A. 1893 [1961]. Catalogue of Snakes in the British Museum (Natural History). New York: Hafner Publishing Company. 382 pp. 9. Bowler, J.K. 1977. Longevity of reptiles and amphibians in North American collections as of 1 November, 1975. Soc. Study Amphib. Rept. Misc. Publ. Herpetol. Circular No. 6: i-iv + 1-32. 10. Brattstrom, B.H. 1965. Body temperatures of reptiles. Amer. Midl. Nat. 73: 376-422. 11. Cope, E.D. 1877. Synopsis of the cold-blooded Vertebrata, procured by Prof. James Orton during his exploration of Peru in 1876-77. [description of ortonii] Proc. Amer. Phil. Soc. 17: 33-68. 12. Davis, W.B., and H.M. Smith. 1953. Snakes of the Mexican State of Morelos. Herpetologica 8: 133-143. 13. de Vosjoli, P. 1997. A new look at boa constrictors. Vivarium 9(1): 37-43. 14. de Vosjoli, P. 1998. The lure of the red-tailed boa. Vivarium 9(3): 68-69. 15. Dixon, J.R., and P. Soini. 1986. The Reptiles of the Upper Amazon Basin, Iquitos Region, Peru. Part 1. Lizards and Amphisbaenians. Part 2. Crocodilians, Turtles, and Snakes. Milwaukee, Wisconsin: Milwaukee Public Museum. 154 pp. 16. do Amaral, A. 1977. Serpentes do Brasil: Iconografia Colorida. Brazilian Snakes: A Color Iconography. Sao Paulo: Editora da Universidade de Sao Paulo. 247 pp.
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17. Dodd, C.K. 1986. Importation of live snakes and snake products into the United States, 1977-1983. Herpetol. Rev. 17: 76-79. 18. Dodd, C.K. 1987. Status, conservation and management. Pp. 478-513 in Seigel, R.A., J.T. Collins, and S. Novak. Eds. Snakes: Ecology and Evolutionary Biology. New York: MacMillan Publishing Company. 529 pp. 19. Donaldson, M., D. Heyneman, R. Dempster, and L. Garcia. 1975. Epizootic of fatal amebiasis among exhibited snakes: Epidemiologic, pathologic, and chemotherapeutic considerations. Amer. J. Vet. Res. 36: 807-817. 20. Fitch, H.S. 1985. Variation in clutch and litter size in New World reptiles. Univ. Kans. Misc. Publ. No. 76: 1-76. 21. Forcart, L. 1951. Nomenclature remarks on some generic names of the snake Family Boidae. [synonymized Constrictor with Boa] Herpetologica 7: 197-199. 22. Frye, F.L. 1973. Husbandry, Medicine & Surgery in Captive Reptiles. Bonner Springs, Kansas: VM Publishing, Inc. 140 pp. 23. Gensch, W. 1969. Breeding boa hybrids (Constrictor c. constrictor X C. c. imperator) at Dresden Zoo. Internat. Zoo Yearbk. 9: 52. 24. Greene, H.W. 1983. Boa constrictor (boa, béquer, boa constrictor). Pp. 380-382 in Janzen, D.H. Ed. 1983. Costa Rican Natural History. Chicago and London: The University of Chicago Press. 816 pp. 25. Hardy, L.M., and R.W. McDiarmid. 1969. The amphibians and reptiles of Sinaloa, México. Univ. Kans. Publ. Mus. Nat. Hist. 18: 39-252. 26. Hoff, G.L., F.L. Frye, and E.R. Jackson. 1984. Diseases of Amphibians and Reptiles. New York and London: Plenum Press. 784 pp. 27. Hoge, A.R., S.A.R.W.D.L. Romano, and C.L. Cordeiro. 1976/1977. Contribuiçao ao conhecimento das serpentes do Maranhao, Brasil. (Serpentes, Boidae, Colubridae e Viperidae). Mem. Inst. Butantan 40/41: 37-52. 28. Hoover, E.E. 1936. On the birth of Constrictor constrictor imperator in captivity. Copeia 1936: 62. 29. Huff, T.A. 1980. Captive propagation of the Subfamily Boinae with emphasis on the Genus Epicrates. Pp. 125-134 in Murphy, J.B., and J.T. Collins. Eds. 1980. SSAR Contributions to Herpetology Number 1: Reproductive Biology and Diseases of Captive Reptiles. Lawrence, Kansas: Society for the Study of Amphibians and Reptiles. 277 pp. 30. Klingenberg, R. 1996. In search of it. Vivarium 8(3): 56-57. 31. Klingenberg, R. 1997a. IBD: Coming to your collection next? Vivarium 8(4): 38-41. 32. Klingenberg, R. 1997b. Inclusion Body Disease (IBD) Update. Vivarium 9(2): 6-8. 33. Klingenberg, R. 1998. Rodent cuisine: Considerations and cautions. Vivarium 10(1): 15-16, 60. 34. Kluge, A.G. 1991. Boine snake phylogeny and research cycles. Misc. Publ. Mus. Zool. Univ. Michigan 178: 1-58. 35. Langhammer, P. 1983. A new subspecies of boa constrictor, Boa constrictor melanogaster, from Ecuador (Serpentes: Boidae). [description of melanogaster] Trop. Fish Hobbyist 32: 70-79. 36. Lazell, J.D., Jr. 1964. The Lesser Antillean representatives of Bothrops and Constrictor. [description of nebulosa and resurrection of orophias] Bull. Mus. Comp. Zool. 132: 245-273. 37. Logan, T. 1972. A method of heating reptile terraria. Internat. Zoo Yearbk. 12: 91-93. 38. Marcus, L.C. 1980. Bacterial infections in reptiles. Pp. 211-221 in Murphy, J.B., and J.T. Collins. Eds. 1980. SSAR Contributions to Herpetology Number 1: Reproductive Biology and Diseases of Captive Reptiles. Lawrence, Kansas: Society for the Study of Amphibians and Reptiles. 277 pp. 39. McAllister, C.T., R. Lenington, and S. Tucker. 1995. Notes on the general ecology of Cryptosporidium spp. Vivarium 7(3): 10-12. 40. McGinnis, S.M., and R.G. Moore. 1969. Thermoregulation in the boa constrictor (Boa constrictor). Herpetologica 25: 38-45. 41. Meerovitch, E. 1960. Thermal barrier to the infectivity of Entamoeba invadens in snakes. Nature 185: 631. 42. Meyer-Holzapfel, M. 1969. Notes on the breeding and egg-laying of some reptiles at Berne Zoo. Internat. Zoo Yearbk. 9: 20-23. 43. Mole, R.R. 1924. 11. The Trinidad snakes. Proc. Zool. Soc. Lond. 1924: 235-278. 44. Mole, R.R., and F.W. Ulrich. 1894. 3. Biological notes upon some of the Ophidia of Trinidad, B.W.I., with a preliminary list of the species recorded from the Island. Proc. Zool. Soc. London 1894: 499-518.
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45. Montgomery, G.G., and A.S. Rand. 1978. Movements, body temperature and hunting strategy of a Boa constrictor. Copeia 1978: 532-533. 46. Murphy, J.B. 1973. The use of the macrolide antibiotic tylosin in the treatment of reptilian respiratory infections. Brit. J. Herp. 4: 317-321. 47. Myres, B.C., and M.M. Eells. 1968. Thermal aggregation in Boa constrictor. Herpetologica 24: 61-66. 48. Napolitano, R.L., E.P. Dolensek, and J.L. Behler. 1979. Reptilian amoebiasis. Internat. Zoo Yearbk. 19: 126-131. 49. Neill, W.T. 1962. The reproductive cycle of snakes in a tropical region, British Honduras. Quart. J. Fla. Acad. Sci. 25: 234-253. 50. Neill, W.T., and R. Allen. 1962. Reptiles of the Cambridge Expedition to British Honduras 1959-60. Herpetologica 18: 79-91. 51. Otero de la Espriella, R. 1978. La Boa: Su Cria y Aprovechamiento Economico. Manzinales, Colombia: Editorial La Patria. 153 pp. 52. Peters , J.A., and B. Orejas-Miranda. 1970. Catalogue of the Neotropical Squamate: Part I. Snakes. United States National Museum Bulletin 297. Washington: Smithsonian Institution Press. 347 pp. 53. Philippi, R.A. 1873. Ueber die Boa der westlichen Provinzen der Argentinischen Republik. [description of occidentalis] Zeitsch. Ges. Naturwiss. 41: 127-130. 54. Price, R.M., and P. Russo. 1991. Revisionary comments on the Genus Boa with the description of a new subspecies of Boa constrictor from Peru. The Snake 23: 29-35. 55. Regal, P.J. 1966. Thermophilic response following feeding in certain reptiles. Copeia 1966: 588-590. 56. Roze, J.A. 1966. La Taxanómia u Zoogeográfia de los Ofidios en Venezuela. Caracas, Venezuela: Universidad Central de Venezuela. 362 pp. 57. Savage, J.M. 1966. The origins and history of the Central American herpetofauna. Copeia 1966: 719-766. 58. Schmidt, K.P., and W.F. Walker, Jr. 1943. Snakes of the Peruvian coastal region. Publ. Field Mus. Nat. Hist. Chicago (Zool. Ser.) 24: 297-324. 59. Schumacher, J., E.R. Jacobson, B.L. Homer, and J.M. Gaskin. 1994. Inclusion body disease in boid snakes. J. Zoo. Wildlife Med. 25: 511-524. 60. Schwartz, A., and R. Thomas. 1975. A Check-List of West Indian Amphibians and Reptiles. Pittsburgh, Pennsylvania: Carnegie Museum of Natural History. 216 pp. 61. Smith, H.M. 1943. Summary of the collections of snakes and crocodilians made in Mexico under the Walter Rathbone Bacon Traveling Scholarship. [description of sigma] Proc. U.S. Nat. Mus. 43(3169): 393-504. 62. Stimson, A.F. 1969. Liste der rezenten amphibien und reptilien. Boidae (Boinae + Bolyeriinae + Loxoceminae + Pythoninae). Das Tierreich 89: 1-49. 63. Stuart, L.C. 1935. A contribution to a knowledge of the herpetology of a portion of the savannah region of central Petén, Guatemala. Misc. Publ. Mus. Zool. Univ. Mich. 29: 1-56. 64. Stuart, L.C. 1948. The amphibians and reptiles of Alta Verapaz, Guatemala. Misc. Publ. Mus. Zool. Univ. Mich. 69: 1-109. 65. Stull, O.G. 1932. Five new subspecies of the Family Boidae. [description of amarali] Occ. Pap. Boston Soc. Nat. Hist. 8: 25-30. 66. Stull, O.G. 1935. A check list of the Family Boidae. Proc. Boston Soc. Nat. Hist. 40: 387-408. 67. Van Mierop, L.W.S., and E.L. Bessette. 1981. Reproduction of the ball python, Python regius, in captivity. Herpetol. Rev. 12: 20-22. 68. Vanzolini, P.E., A.M. Ramos-Costa, and L.J. Vitt. 1980. Rèpteis das Caatingas. Rio de Janeiro: Academia Brasileira de Ciéncias. 161 pp. 69. Vivarium Research Group, Inc. 1998. Designing tropical vivaria for boas and pythons. Vivarium 9(5): 7578. 70. Wilson, L.D., and J.R. Meyer. 1982. The Snakes of Honduras. Milwaukee, Wisconsin: Milwaukee Public Museum. 159 pp. 71. Wright, K. 1995. Blister diseases. Vivarium 7(2): 10. 72. Zweifel, R.G. 1960. Results of the Puritan-American Museum of Natural History Expedition to western Mexico. 9. Herpetology of the Tres Marías Islands. [synonymized sigma with imperator]. Bull. Am. Mus. Nat. Hist. 119: 81-128.

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