Brief communications 273
7. Kirkbride CA, Gates CE, Collins JE: 1986, Abortion in sheep ed. Krieg NR, Holt JG, vol. 1, pp. 633-634. Williams and
caused by a nonclassified, anaerobic, flagellated bacterium. Am Wilkins, Baltimore, MD.
J Vet Res 47:259-262. 11. Osbaldiston GW, Stowe EC: 1971, The cultivation and iden-
8. Kirkbride CA, Gates CE, Collins JE, Ritchie AE: 1985, Ovine tification of anaerobic bacteria in the veterinary diagnostic lab-
abortion associated with an anaerobic bacterium. J Am Vet Med oratory. Can Vet J 12:45-52.
Assoc 186:789-791. 12. Prescott JF: 1979, Identification of some anaerobic bacteria in
9. Kirkbride CA, Martinovich D, Woodhouse DA: 1977, Im- nonspecific anaerobic infections in animals. Can J Comp Med
munoglobulins and lesions in aborted bovine foetuses. NZ Vet 43:193-199.
J 25:180-187. 13. van den Bogarrd AEJM, Hazen MJ: 1986, Presumptive diag-
10. Moore WEB, Holdeman LV, Kelley RW: 1984, Genus II. Fu- nosis of anaerobic infections in veterinary medicine by gas chro-
sobacterium. In: Bergey’s manual of systematic bacteriology, matography. Proc IVth Int Symp Vet Lab Diagn, pp. 274-278.
J Vet Diagn Invest 1:273-275 (1989)
Disseminated Mycobacterium avium infection in a dog
Cynthia C. Shackelford, Willie M. Reed
Mycobacterium infection was first reported in the dog in gram revealed a leukocytosis (white blood cells, 18,000/µl
1817.l Since that time Mycobacterium tuberculosis and My- Blood chemistries revealed leakage of hepatic enzymes (se-
cobacterium bovis have been the most frequently reported rum glutamic pyruvate transaminase, 822 IU) and slight hy-
species associated with canine mycobacteriosis. Dogs are poproteinemia (total protein, 5.0 mg/dl). Three small masses
considered equally susceptible to M. tuberculosis and M. bo- were detected in the hilar area of the lungs on radiographs.
vis but have a higher incidence of infection with M. tuber- Fine needle aspirates of the popliteal lymph node revealed
culosis. 1-7,9 Both organisms have been associated with pul- acid-fast, rod-shaped bacteria morphologically consistent with
monary, cutaneous, gastrointestinal, and disseminated Mycobacteria sp. within macrophages. The dog was placed
disease.4 Mycobacterium avium infection has been described on isoniazid for 10 months but continued to deteriorate. She
in many mammalian species including dogs, cats, primates, was euthanatized and presented to the Purdue University
swine, cattle, sheep, and horses.2,8 It is considered rare in Animal Disease Diagnostic Laboratory for necropsy.
dogs and cats presumably due to their innate resistance to At necropsy, the dog was severely emaciated. Tracheo-
this organism. Infection in dogs and cats results from bronchial lymph nodes were enlarged and contained multiple
ingestion of infected meat or contact with infected soil or foci of caseous necrosis. The pleural cavity contained ap-
fomites.5,6,8 proximately 50 ml of serosanguinous fluid. Several subpleu-
After mycobacteria enter the body through either the re- ral granulomas were associated with osteolysis of adjacent
spiratory or alimentary tract, they are engulfed by phagocytic ribs. The spleen was enlarged and irregularly shaped, weighed
cells and continue to thrive and multiply. Granulomas fre- 450 g, and contained depressed pale foci. Purulent exudate
quently form in an attempt to contain the organisms. Or- was present in fascial planes of thigh muscles.
ganisms may spread into adjacent tissue or throughout the Histologically, there was massive infiltration of macro-
body by lymphatic or hematogenous dissemination. Gran- phages in the spleen, liver, small intestine, lymph nodes, and
ulomas induced by mycobacteria typically consist of areas bone marrow with lesser involvement of the lung and kid-
of focal caseous necrosis surrounded by macrophages, lym- neys. The spleen was diffusely infiltrated and normal archi-
phocytes, and plasma cells. Fibrous encapsulation frequently tecture was effaced by macrophages and giant cells leaving
occurs. Calcification of the granuloma is sometimes present; only scarce remnants of white pulp around central arterioles
however, liquefaction of the necrotic central portion is rarely (Fig. 1). The larger splenic arteries contained partially or-
observed in camivores.3,6,7 Giant cell formation, which occurs ganized fibrin thrombi. There were scattered foci of splenic
frequently in other species, is uncommon in dogs.6 Short- necrosis. In addition, there were scattered foci of extramed-
chained, beaded, slightly pleomorphic, acid-alcohol-fast ba- ullary hematopoiesis. The liver contained randomly distrib-
cilli may be detected intracellularly at the periphery of ne- uted, discrete foci of intense infiltration of macrophages and
crotic lesions.6,7 giant cells (Fig. 2) resulting in compression of adjacent he-
A 3-year-old spayed female basset hound with a history patocytes. Additional hepatic alterations included sinusoidal
of anorexia, shivering, hyperthermia, and generalized lymph- ectasia and congestion. Sections of jejunum contained marked
adenopathy was presented to a local veterinarian. The hemo- infiltrations of the lamina propria and submucosa by Lan-
ghans’ type giant cells containing large amounts of granular
From the Animal Disease Diagnostic Laboratory, Purdue Uni- eosinophilic cytoplasm and high numbers of peripherally ar-
versity, West Lafayette, IN 47907. ranged oval vesiculate nuclei. All lymph nodes and surround-
Received for publication January 28, 1989. ing connective tissue were diffusely infiltrated with macro-
Figure 1. Diffuse infiltration of the splenic stroma by macrophages and giant cells replacing red and white pulp. HE stain.
phages. The bone marrow was replaced by macrophages, had spectively. Ziehl-Neelsen’s acid-fast stain revealed myriads
multiple foci of necrosis, and contained scattered aggregates of acid-fast bacilli within the cytoplasm of macrophages,
of erythropoietic cells. The lung and kidney contained oc- giant cells, neutrophils and free among necrotic debris (Fig.
casional small aggregates of macrophages and few lympho- 3). Smears of the thoracic fluid were highly cellular and con-
cytes surrounding vessels and within the interstitium, re- tained a dense population of foamy macrophages, neutro-
Figure 2. Hepatic granulomas compressing adjacent hepatic cords are composed of giant cells, macrophages, and lymphocytes. HE
Figure 3. Intracytoplasmic acid-fast rods within splenic macrophages. Ziehl-Neelsen’s stain.
phils, and sheets of mesothelial cells. Mycobacterium avium 2. Feldman WH: 1930, The pathogenicity for dogs of bacilli of
was isolated from the retropharyngeal lymph nodes and spleen. avian tuberculosis. J Am Vet Med Assoc 76:399-419.
The diagnosis of disseminated M. avium infection was 3. Ferber JA, Dilts CE, Scherzo CS: 1983, Tuberculosis in a dog.
based on gross, histopathologic, cytologic, and bacteriologic J Am Vet Med Assoc 183:117.
studies. The source of the infection was not determined; how- 4. Foster ES, Scavelli TD, Greenlee PG, Gilbertson SR: 1986, Cu-
taneous lesion caused by Mycobacterium tuberculosis in a dog. J
ever, the animal had access to a pond which was frequented
Am Vet Med Assoc 188:1188-l190.
by migrating waterfowl. The extensive intestinal lesions in 5. Friend SCE, Russell EG, Hartley WJ, Everist P: 1979, Infection
this dog suggest an oral route of infection with hematogenous of a dog with Mycobacterium avium serotype II. Vet Patho1 16:
and lymphatic dissemination. The immunologic status of the 381-384.
dog was unknown; however, the severity and the massive 6. Greene CE: 1984, Mycobacterial infections. In: Clinical micro-
dissemination of lesions suggest that the dog may have been biology and infectious diseases of the dog and cat, pp. 633-645.
immunosuppressed. W. B. Saunders Co., Philadelphia, PA.
Acknowledgements. The authors thank Dr. David Liddell 7. Liu SK, Weitzmann I, Johnson GG: 1980, Canine tuberculosis.
for the clinical evaluation and submission of this case, and J Am Vet Med Assoc 177:164-167.
the National Veterinary Services Laboratory, Ames, IA, for 8. Thoen CO, Karlson AG, Himes EM: 1981, Mycobacterial in-
fections in animals. Rev Infect Dis 3(5):960-972.
the isolation and identification of the organism. Submitted
9. Walsh KM, Losco PE: 1984, Canine mycobacteriosis: a case
as journal paper no. 11,220, Purdue University, Agricultural report. J Am Anim Hosp Assoc 20:295-299.
Experiment Station, West Lafayette, IN 47907.
1. Blain DP: 1913, Tuberculosis in the dog, cat and bird. Vet Rec