Current Findings in the Regional Veterinary Laboratories August 2005 Cattle Kilkenny examined a one-month old calf with a history of inappetance, abdominal pain and jaundice. A fluorescent antibody test (FAT) was positive for Leptospira icterohaemorrhagiae. Limerick also suspected that leptospirosis caused the death of a five-month old calf. The calf died within twenty-four hours of being found in a recumbent state by the herd owner. Post-mortem examination showed pronounced jaundice, widespread petechiation and oedema. A 15-month old bullock which suffered intermittent scour and ill thrift for two weeks and which presented with neurological symptoms terminally was presented to Dublin. Histolopathology of the liver revealed extensive fibrosis, megalocytosis and bile duct proliferation, pathological changes highly suggestive of ragwort toxicity. Histological examination of the brain revealed extensive vacuolation of tissues indicative of hepatic encephalopathy. Ragwort poisoning was also diagnosed in an eight-month old weanling submitted to Limerick. This was the second animal to die within a couple of days. Twelve animals from the same herd died in March from the same condition. Athlone reported clostridial myocarditis in a six-month old calf. Clostridium chauvoei involvement was confirmed using an FAT. Blackleg was also diagnosed by Sligo in a four-month old suckler calf from an unvaccinated herd. Two of the best calves in the herd had died on the two hottest days of the year (29ºC). Dublin found that the sudden death of a six-month old pedigree Limousin heifer was linked to Clostridium novyi infection. There was an extensive pleuritis and pericarditis with large volume of pleural fluid. Athlone investigated an outbreak of fog fever in a herd of suckler cows. Initial signs were observed six days after the animals had been moved to lush after-grass. Four deaths occurred in the group of forty cows. Sligo reported several outbreaks of a syndrome of coughing and milk drop in adult dairy cows, where the epidemiology was suggestive of hoose re-infection. This is seen where animals with an acquired resistance to Dictyocaulus viviparus are grazed on heavily infected pastures. Although this immunity is sufficient to prevent the establishment of patent infections, the resulting hypersensitive immune reaction to the migrating larvae in the lungs is sufficient to cause respiratory disease and production losses. Sligo reported that acute bracken poisoning was diagnosed on four separate holdings during July. The main presenting signs were severe haematuria, petechial and ecchymotic haemorrhages on serosal surfaces and frank haemorrhage into the GIT. One carcass submitted showed significant haemorrhage from injection sites where therapy had been administered. (Figure 1). High bulk milk somatic cell counts are typically a problem in dairy herds at this time of year. 331 individual milk samples were examined by the RVLs during the month (Figure 2). Staphylococcus aureus remained the most commonly isolated pathogen, being cultured from 145 (44 per cent) of the samples tested. The antibiotic sensitivity patterns remain pretty consistent, with penicillin resistant strains acounting for over 50 per cent of the Staph. aureus isolates (Figure 3). Sheep Dublin examined a three-month old ram lamb that had died suddenly. The ram was on a grass diet with barley supplementation. Post-mortem findings were consistent with a diagnosis of rumen acidosis. Rumen pH was 4.4 and protozoan motility was absent. A pedigree Suffolk ram was submitted to Sligo with a history of chronic weight loss and diarrhoea. There had been no response to treatment with anthelmintics and minerals/trace elements. Acid-fast organisms were observed in a faecal smear and Johne’s disease was suspected. The post mortem findings tended to support this tentative clinical diagnosis, with extensive thickening and severe corrugation of the wall of the large and lower small intestine (Figure 4). However, a faecal sample contained 2,000 strongyle eggs per gram and histological examination revealed lesions suggestive of severe and chronic parasite challenge, including villous atrophy, granulomatous eosinophilic enteritis and the presence of numerous nematode larvae in the bowel wall. The failure to respond to repeated anthelmintic therapy might reflect the level of challenge and the fact that the ram was returned to the same heavily contaminated paddock after each treatment. Poultry A drop in egg production and egg quality in a large free range layer flock investigated by Cork was ascribed to egg drop syndrome (EDS) based on increased titres to EDS virus from the first to the second monitoring of flock blood samples. Cork identified necrotic enteritis disease (Clostridium perfringens was isolated) in broiler breeders aged 21 weeks. The flock was divided between three houses and the disease was confirmed in birds from two of the houses. Strict hygienic precautions were introduced and the disease did not occur in birds in the third house while treatment of the birds in the other two houses suppressed the disease. Equine Limerick reported Rhodococcus equi infection in a six-week old foal. The foal was ill for five days and was being treated for pneumonia. Brocho-pneumonia was the principal lesion seen on post-mortem examination. Sligo gave advice to a practitioner who wished to carry out a field postmortem on a mare that had died following an acute colic. There had been no response to treatment and a severe diarrhoea was seen just before death. The post-mortem had revealed lesions consistent with a necrotic colitis. This scenario was a recognised complication of treating foals with erythromycin for Rhodococcus equi-pneumonia , where coprophagia of the foal's faeces by the dam can lead to Clostridium difficile overgrowth and fatal acute colitis in the mare. In this case, although the mare’s faol was on treatment for Rhodococcus equi-pneumonia with erythromycin, the condition was not confirmed, nor was Clostridium difficile isolated, but it seems a likely possibility. Other Species Limerick diagnosed heavy coccidial infection in pigeons with a history of diarrhoea and ill thrift. Pigeons from a loft where a large number of deaths had occurred were examined by Athlone and were found to have succumbed to aflatoxin poisoning. Cork examined a juvenile hen harrier (Circus cyaneus) that had been found dead. No gross lesions were seen but Erysipelothrix rhusiopathiae was isolated from organs cultured. Twelve pheasants, six-weeks old, from a group of one thousand, were submitted to Cork for examination following the deaths of up to ten per cent of the group. The birds had been moved to a new pen two days before the deaths started. The gizzards of all twelve birds were impacted, principally with seeds of the common cleaver (Galium aparine) (Figure 5). In another group of pheasants, Syngamus trachea infection was confirmed at post-mortem in sixweek old pheasants. Fifty per cent losses had occurred in a group of 1,400 birds brought in 10 days previously. CAPTIONS FOR PHOTOS Figure 1 “Carcass and urine sample of an animal with bracken poisoning – photo Michéal Casey” Figure 2 “Bacterial isolates from milk samples submitted to the RVLs” Figure 3 “Staphylococcus aureus antibiotic sensitivity patterns seen during August” Figure 4 “Intestinal wall of a ram with parasitic enteritis – photo Michéal Casey” Figure 5 <insert 0508Cork2> “Galium aparine- The common cleaver – photo Sorcha Spillane”