Current Findings in the Regional Veterinary Laboratories October 2004
Bovine abortions associated with salmonella infections Parasitic gastroenteritis in cattle and sheep Milk sample tests Strangles Fowl Cholera
Cattle
Historically, S. dublin abortions as diagnosed by Cork show cyclical fluctuations with the year 2003 having the lowest number recorded for several years. Cork isolated Salmonella dublin from fifteen of the 50 foetuses submitted in the month, this compares with eleven isolations from 59 foetuses in the same month last year, an increase of 10 per cent. The two herds with most multiple abortions from S. dublin this month were not vaccinating against S. dublin. Analysis of data from foetal submissions to Cork for the last fifteen years shows the reduction in relative risk as a result of S. dublin vaccination at 0.62 (publication in preparation). Limerick RVL has recorded a sharp rise in the number of Salmonella dublin-associated bovine abortions examined during the month. The organism was isolated from 65% of the foetal samples submitted. Kilkenny isolated S. dublin in 21% of bovine foetuses submitted. A stillborn Friesian calf submitted to Limerick RVL from a farm where the perinatal calf mortality was higher than expected, was found to have a grossly enlarged thyroid gland (91grams compared to an approximate normal of less than 22grams). Histopathological examination confirmed that the gland was hyperplastic. Iodine deficiency was suspected. Kilkenny diagnosed several cases of Blackleg (Clostridium chauvoei) during October. All cases were submitted with a history of “being found dead”. The age range was from six to nine months and typical lesions were seen in the hindquarters, forequarters or in the heart. A nine-month-old bovine was submitted to Kilkenny for PME. This animal had a severe pneumonia on examination, the lung was 80% consolidated. Widespread emphysema was seen and blood clots and froth were present in the trachea and bronchi. The Fluorescent Antibody Test (FAT) on lung tissue was positive for Respiratory Syncytial Virus (RSV). Parasitic gastroenteritis (PGE) was the principal finding in weanlings by Cork, diagnoses was established from both post mortems and submitted faecal samples. Four deaths within 24 hours in one group were identified by Cork as being due to combined parasitic bronchopneumonia and PGE. While the group had been dosed five weeks previously they were returned to the permanent grazing. The same group had had a severe bout of coccidiosis in August. Management factors were also identified by Cork where PGE had killed three weanlings in two days; they were from a farm that had been recently acquired and where the dosing regime had been neglected. Kilkenny diagnosed a number of cases of hoose during October. A thirteen-month-old bovine was submitted to Kilkenny with a history of being off form and breathing heavily for a couple days before death. There was extensive reddening of the mucosa of all of the abomasum
and most of the small intestine. The FAT was positive for Clostridium sordelli. Athlone investigated a case of recumbency and hind limb lameness in weanlings/yearlings. One four-month-old calf showed signs of stiffness before becoming recumbent. While recumbent he continued to eat but could only stand with assistance. This animal was euthanased and at histopathological examination was found to have wallerian degeneration and chromatolysis, which explained his recumbency. The lesions were consistent with those reported for the low copper/low magnesium complex as has been reported previously in well fed suckled calves. This animal did not show hypocupraemia or hypomagnesaemia but copper therapy had been administered prior to the involvement of the laboratory. One of two comrade calves showed hind limb lameness and the other showed stiffness on all four limbs. Limerick RVL diagnosed bacillary haemoglobinuria as the cause of sudden death of a yearling heifer in North Kerry. Two other animals had died under similar circumstances in the previous few months. Mycoplasma bovis was isolated from a weanling bull, which died suddenly, within two weeks of purchase from a weanling sale and in which subacute to chronic pneumonia lesions were found by Dublin. Sligo investigated deaths in a group of twentymonth-old store steers where severe acute respiratory disease caused three deaths in the space of a week. One animal was submitted with a history of having collapsed and died after a short and acute respiratory episode. There was a severe fulminating pneumonia and a diphtheritic trachaeitis. IBR is suspected but not confirmed at time of writing. Dublin reported two outbreaks of suspect botulism. One farm was associated with the exposure to poultry litter spread on pasture where three animals died with signs of botulism. On another farm, situated adjacent to a holding facility for litter, clinical signs of botulism have been observed in three animals, each of which died, at different times over a period of one year. Toxin isolation is being attempted. A cow necropsied by Cork had vegetative endocarditis, Arcanobacter pyogenes isolated. The RVLs receive a large number of bovine milk samples at this time of year. Of 242 milk sample submitted to Limerick RVL during the month, coliforms were isolated from 116, Staphylococcus aureus from 94, Streptococcus dysgalactiae from 16, and Streptococcus uberis from two.
Sheep
Sligo reported several cases of parasitic gastroenteritis (PGE) in lambs. One outbreak was on an organic farm, while another was on a holding that had used a benzimidazole product ('white drench') exclusively for over eight years. Benzimidazole resistance is suspected. Fattening lambs in which parasitic gastroenteritis was diagnosed by Cork had subsequent losses from acidosis when beet pulp, fed after worm treatment to help improve body condition, was ingested to excess. Kilkenny also diagnosed several cases of (PGE) in lambs. One particular case had 35,800 strongyle eggs per gram (epg) of faeces, 1,500 Nematodirus epg, 700 Strongyloides epg and a heavy tapeworm burden. A four-year-old ewe was submitted to Kilkenny with a history of being found dead a day after being scanned.A large abscess was seen caudoventral to the cerebellum (see figure 1). Bacterial meningitis was identified on histological examination.
Other Species
A yearling filly submitted to Limerick RVL, following unsuccessful treatment for colic, was found to have died as a result of a gastric rupture, a sequel to gastric dilation. A six-month old foal, also submitted to Limerick RVL, had a ruptured small intestine, a sequel to very heavy parasitic infection. Large numbers of the worms identified as Parascaris equorum were found in the intestines. Dublin isolated Streptococcus equi subspecies equi, the etiological agent of equine strangles, from nasal swabs submitted from a group of four sport horses, which were recently introduced onto the premises. The classical clinical signs associated with strangles of nasal discharge, enlarged retropharyngeal lymph nodes, pyrexia, lethargy, and in two of the horses, eruption of the retropharyngeal lymph nodes with discharge of a suppurative exudate, were observed. One horse was isolated from the others because of continuing discharge of mucopurulent exudate, which was evident on the ground and on feed and water containers, all of which will require cleaning and disinfection. In accordance with the Code of Practice for Equine diseases these horses have been isolated and their infectious status will be monitored by repeated collection and culture of nasal swabs until three successive swabs remain negative for Streptococcus equi subspecies equi. Kilkenny diagnosed Fowl Cholera (Pasteurella multocida infection) in a turkey with a history of sudden death. This was the second case in the flock in a twenty-four hour period. Losses in young turkey poults, after purchase “out-of-heat” for fattening, were found by Cork to be due to both starve-outs and coccidiosis. One of two large turkey breeding stags submitted to Cork died from a ruptured aorta. The second had a pericarditis of undiagnosed aetiology. Kilkenny diagnosed impaction of the gizzard in a pheasant, fifteen to twenty fruit stones were found in the gizzard. A ten-week-old greyhound pup was submitted to Kilkenny for PME. Parvovirus was suspected on gross examination (see figure 2) and this was confirmed on histology. Campylobacter spp. was also isolated from the intestine. It is important to remember that dogs with parvovirus infections could also have zoonotic diseases e.g Campylobacter spp. or Salmonella spp. infections. Euthanasia was undertaken on the ten-month old hunting terrier, which had been sole companion of the dog diagnosed by Cork with tuberculosis of the lungs and kidneys (June report, Ibid. (2003) 57(9) p520). While no gross or histological lesions were found in the second dog, Mycobacterium bovis was isolated on culture from an amalgam of lymph node tissue. Cork isolated Salmonella typhimurium from a six-week-old Siberian Husky pup submitted from a breeding premises. The pup had clinical signs of gastroenteritis before death. PHOTO CAPTIONS
“Cranial abscess in a ewe – photo Donal Toolan”
“Parvovirus in a greyhound pup – photo Donal Toolan”