Current Findings in the Regional Veterinary Laboratories

July 2004

Cattle

Salmonella dublin was isolated from an aborted foetus presented to Dublin RVL from a herd in which there have been at least three abortions within ten days. In another 60 cow dairy herd investigated by Dublin, five abortions occurred at six to seven months gestation but only placental material had been found. Examination of blood samples from a representative sample of twenty cows revealed antibodies to both Neospora caninum and Leptospira hardjo. The investigation is ongoing. Two placentae were submitted to Kilkenny from one farm where two cows had aborted. The herdowner was unable to locate the foetuses. Necrosis of the cotyledons was noted on gross examination and Salmonella dublin was isolated from both placentas. A titre of 1/320 at both the O and H antigens for Salmonella dublin was obtained from a blood sample from one of the cows. This herd had not been vaccinated for Salmonella. This case highlights the importance of submitting the placenta for examination from cows that abort and especially where the foetus cannot be located. Blood samples should be taken from the cow for Brucella abortus and sent to the Brucellosis Laboratory in Cork and to the local RVL for Salmonella, Leptospira and Neospora testing.

A six-week old calf with a history of sudden death was submitted to Limerick RVL. Death was found to have resulted from the rupture of an abomasal abscess with leakage of the contents into the abdominal cavity. Kilkenny diagnosed a number of cases of abomasal ulceration, perforation and death due to acute peritonitis during July. These are usually large single ulcers that develop over a considerable period of time. Death is usually rapid due to the acute peritonitis. Clinical signs noted in some cases are reluctance to stand or drink, colic and a swollen abdomen. In many cases the excess peritoneal fluid can be detected prior to opening the abdomen.

Two outbreaks of cerebrocortical necrosis (CCN) were seen by Limerick during the month. Both outbreaks occurred in groups of three to six-month-old calves at grass. Nine calves were affected in one group. Kilkenny also diagnosed a number of cases CCN during the month. Three cases were submitted from one farm where a total of five calves died.

Hoose pneumonia associated deaths in calves were seen by Limerick RVL during the month.

Parasitic gastroenteritis was the most frequent diagnosis from faecal specimens submitted to the Cork laboratory. Athlone detected Cryptosporidia spp. in 19% and Coccidial oocysts in 17% of calf faecal samples submitted in the first half of 2004. Fluke eggs were detected in 6% of faecal samples submitted from older animals.

Dublin examined a three-month old calf that had chronic non-responsive ill-thrift with pyrexia and diarrhoea and found a serofibrinous peritonitis and enteritis. A cohort calf from the same suckler herd had a severe fibrinous arthritis of the right stifle and hip joints and chronic bronchopneumonia with multifocal areas of necrosis of a few millimetre diameter surrounded by mononuclear cell infiltrations, all of which is consistent with the characteristic pathology of Mycoplasma bovis, for which culture tests are ongoing.

Kilkenny diagnosed blackleg in a two-month-old calf. However, the post–mortem findings were not typical of blackleg. There was haemorrhage in the fat around both kidneys and in mesentery of the duodenum. The abdomen was full of red liquid. Only one ilio-psoas muscle and a small area of muscle in the neck were dark in colour but there was no gas formation seen. The fluorescent antibody test (FAT) for Clostridium chauvoei was positive.

A calf aged three months received by Cork had a cellulitis extending from the right costal area through the cervical muscles to the occipital foramen and extending into the right cerebral hemicortex with caseous material within the leptomeninges and a bacterial meningitis apparent on histopathology. No pathogen was identified on culture. Antibiotic therapy probably interfered with the bacteriology results.

Lymphosarcoma was diagnosed by Dublin based on a formalin fixed tissue sample collected from the thoracic cavity of a two-year old Charolais bullock at slaughter.

Limerick RVL is investigating an outbreak of Klebsiella-associated mastitis in a herd of dairy cows. Six cases have occurred over a six-week period. It is unusual to find this type of environmental mastitis at this time of year, when cows are at grass. It is a pathogen more often associated with cows housed on sawdust bedding.

Sheep and Goats

Athlone detected Coccidial oocysts in over 50% of faecal samples submitted from scouring lambs in the first half of 2004. Fluke eggs were detected in 15% of faecal samples submitted from adult sheep. Faeces samples from one juvenile and two adult goats from the same herd, examined by Cork had high Strongyle species egg counts.

Poultry

Cholera (Pasteurella multocida isolated) was identified by Cork in a broiler breeder flock. The broilers had gross lesions of swollen wattles and peritonitis and were also over-fat. Coliform peritonitis/septicaemia was identified in other broiler breeder flocks by Cork. The death of 15 six-week-old broiler chickens from a small group of 100 birds was found by Limerick RVL to be associated with broiler ascites syndrome.

Of three turkey stags weighing from 22 to 24 kgs submitted to Cork from a breeding unit, one had pneumonia – Staphylococcus aureus was isolated – one had haemorrhaged from a rupture at the base of the heart and the third had no specific findings.

Dogs

A greyhound pup two months of age submitted live to Cork had developed a domed cranium, as had two siblings from the litter of ten. Post mortem examination showed a marked hydrocephalus (see figure 1). Histopathology showed no evidence of viral infection. Genetic factors may be involved.

A three-month-old greyhound pup was submitted to Kilkenny with a suspected torsion of the intestine. On examination it was found that the abdomen was full of a mal-odorous dirty grey fluid (see figure 2) and the omentum was very reddened, thickened and inflamed . Strep equi zooepidemicus was isolated on bacterial culture from the peritoneal fluid and the liver. Histological examination confirmed inflammation of the omentum and peritoneum. There was also a multifocal hepatitis present. Demodectic mange mites were detected in one of three canine skin scrapings submitted to Limerick RVL. The samples were taken from three dogs that had a history of intense pruritis. Athlone reported that a mast cell tumour was diagnosed following histopathological examination of a lump that was removed from behind the ear of a dog. It had been present for one month prior to removal. Recurrence of mast cell tumours is common and metastases may occur initially to local lymph nodes.

Figure 1 caption “Hydrocephalus in a two-month-old greyhound pup – photo Sorcha Spillane”

Figure 2 - caption “Dirty grey fluid in the abdomen of a pup – photo Donal Toolan”