April 2008

Current Findings in the Regional Veterinary LaboratoriesApril 2008

CattleCongenital chondrodystrophy was diagnosed in a newborn full-term Charolais calf submitted to Limerick. This was one of a number of calves born on the same farm with similar signs. The stock bull sired all affected calves, but the bull had been used in previous years with no problems. Liver Cobalt was low but the significance of this is not known. Bloods from a selection of the dams were tested for Manganese but were all within the normal range. Kilkenny diagnosed a variety of congenital conditions in neonatal calves. One three-day old calf had a congenital blockage between the abomasum and the duodenum, and also between the middle and distal thirds of the small intestine. Another six-day old calf was found to have congenital polycystic kidneys, and a ten-day old calf that died suddenly was found to have a complex heart abnormality. Sligo had three cases of congential atresia coli from one farm during the month. An incidental finding in another neonatal calf examined by Sligo was the complete absence of a tail.

A farm visit was carried out by Athlone to a dairy farm with problems of poor thrive and deaths in calves from as young as two days of age. The calves were reported to be going off their milk and rapidly losing condition. Eleven calves had died at the time of the visit. Pneumonia was considered to be part of the problem, but significantly, one of the dead calves had a liver Cobalt level one hundred times in excess of the normal reference range. Further enquiries revealed that the farmer had been supplementing calves with Cobalt from a few days of age in an effort to address the issue of poor thrive. When he saw that the treatment appeared to be having a positive effect he repeated the dose at regular intervals, eventually leading to Cobalt poisoning.

Intussusception involving six inches of jejunum, with obstruction and necrosis of the bowel was observed by Dublin in a ten-day old suckler calf, which had recovered from diarrhoea but had failed to regain an appetite. A heavy cryptosporidium oocyst burden was detected and this was thought to have been the underlying cause of the enteritis. Two calves (one- and two-weeks of age) with a history of scour and poor thrive were submitted to Dublin from a research farm. Lesions of rumenitis and fungal abomasitis (figure 1) were seen, most likely resulting from repeated feeding with an oesophageal tube. Antibiotic therapy may also have facilitated mycotic colonisation. Myocardial necrosis and polyphasic myopathy affecting the skeletal muscles was seen in the six-day old calf, the cause of which was unknown.

Sligo diagnosed choke in a two-month old calf with a history of mania, polydypsia and eventual collapse and death two days later. The distal oesophagus was obstructed by a cylindrical piece of chopped beet. A two-month old Aberdeen Angus calf, which had presented clinically with bloat and dyspnoea was examined by Athlone. Lesions of severe diffuse peritonitis were seen, with leakage of digesta into the peritoneal cavity. The source of the leak was found to be a perforated abomasal ulcer, the cause of which could not be determined.

Kilkenny examined two calves from two farms where poor thrive and high mortality was reported. The calves had extensive lesions of pneumonia and Salmonella

Dublin was isolated from both. Pasteurella multocida was also isolated from one animal and Arcanobacterium pyogenes from the other. Limerick examined an eight-week old calf with a history of ataxia. Lesions of osteomyelitis were found in the seventh cervical vertebra and culture yielded a pure growth of Salmonella Dublin. Salmonella Dublin was isolated from a single faeces sample submitted to Kilkenny from a dairy herd with a history of milk drop and weight loss.

Sligo diagnosed Type II ostertagiasis in a group of housed weanlings with ill-thrift. The sentinel case had terminal pneumonia from which Mannheimia haemolytica was isolated. Consequences of the wet summer in 2007 continued to be observed into this spring by all RVLs, with the occurrence of liver fluke in some herds where herdowners had little previous experience and for which, control measures were inadequate. Numerous liver flukes (Fasciola hepatica) were found by Dublin in the gall bladder of a recently calved two-year old dairy cow that also had a very hard (fibrosed) liver and thickened “pipe-stem” bile ducts (biliary hyperplasia). The history was one of poor body condition, weakness and recumbency shortly after calving. Blood samples taken from a number of the cohort animals revealed hypoalbuminaemia and elevated liver enzyme levels. Faecal samples were positive for liver fluke eggs.

Bovine viral diarrhoea (BVD) virus was detected in blood samples from two bulls submitted to Athlone from different farms. Both had a history of weight loss. The results serve as a reminder to farmers and veterinary practitioners that stock bulls should be checked for BVD virus before purchase, as a persistently infected bull has enormous ability to spread infection. Sligo diagnosed clostridial orchitis in a bullock that had recently been castrated with a burdizzo. The lesions were confined to the left testicle and spermatic cord.

SheepSligo isolated Bacillus licheniformis (a common cause of bovine abortion) from three aborted lambs submitted from one flock.

Athlone diagnosed pulpy kidney disease in three three-week old lambs with a history of sudden death. Kilkenny isolated Streptococcus suis type I from the lung, liver and kidney of a four-week old lamb that had also died suddenly. The lamb had lesions of vegetative endocarditis, with one large nodular growth attached to the right atrio-ventricular valve.

An arterial sarcoma that lead ultimately to blood vessel rupture, haemothorax and sudden death in a four-year old ewe was diagnosed by Sligo. In a separate case, a focally extensive mass attached to the pericardial sac, with blood-stained pericardial and pleural effusions was discovered in a hogget presented to Sligo. The mass was found on histopathological examination to be a lymphoma.

Other SpeciesA 12-year-old pony was submitted to Athlone with a history of sudden death. Haemachromatosis was diagnosed following histoptahological examination. The hepatocytes were laden with haemosiderin, there was periportal bridging fibrosis and megalocytosis. It was considered that cirrhosis (due to ragwort poisoning) predisposed the animal to haematochromatosis. A nineteen-year old thoroughbred

brood mare with a history of severe weight loss and polydypsia was electively euthanased and examined by Limerick. Post mortem examination revealed an enlarged pituitary gland (figure 2). The enlargement was found to be associated with an adenoma of the pars intermedia, which is the most common type of pituitary tumour seen in horses. An eleven-month-old German Shepherd with a history of vomiting and abdominal pain was submitted to Limerick. Post mortem examination showed that rupture of the stomach had occurred as a result of gastric dilation and volvulus.

Limerick diagnosed acute coccidiosis in a goat kid. The animal was anaemic as a result of haemorrhage from the denuded mucosa of the large intestine.

Kilkenny isolated Salmonella arizonae from a faecal sample submitted from a snake with clinical signs of poor form and inappetance.

Sligo diagnosed colisepticaemia in a flock of caged grey partridges where mortality rates were high in young birds. Multifocal hepatic necrosis and hepatomegaly were the most prominent lesions seen on gross examination.

CAPTIONS FOR PHOTOS

Figure 1 “Fungal abomasitis in a two-week old calf – photo Ann Sharpe”

Figure 2 “Enlarged pituitary gland protruding from the base of the cranial cavity (brain removed) of an aged broodmare– photo Alan Johnson”