Current Findings in the Regional Veterinary Laboratories June 2007 Cattle Salmonella typhimurium (DT104) was isolated from the stomach contents of a bovine foetus submitted to Athlone. Appropriate advice was given regarding the zoonotic nature of this pathogen. Kilkenny isolated S. typhimurium DT 104 from calves that were scouring. A vaccination programme against Escherichia coli K99, rotavirus and coronavirus was in place on the farm.
All centres reported cases of cerebrocortical necrosis (CCN) during the month. Apple green florescence on examination of the brain with an ultraviolet lamp was used to provide interim diagnoses in all cases, with confirmation by brain histopathology. An example of one case was a four-month old calf presented to Athlone, one of four calves affected in a group of eight. The calves had been housed for the previous two months. The clinical signs reported included blindness and head pressing. The other calves responded well to B-vitamin and anti-inflammatory treatment.
Athlone diagnosed valvular endocarditis in a yearling bull, which had presented with acute respiratory distress and pyrexia. In addition to the vegetative lesions in the valve and wall of the left ventricle, there was severe pulmonary oedema and congestion. Histopathological examination of the lung showed some evidence of concurrent lungworm infection, but this was considered to be an incidental finding. Parasitic pneumonia (hoose) was confirmed by Athlone to have caused the deaths of two 16-month old heifers submitted with a history of dyspnoea.
Sligo recorded five separate outbreaks of lead poisoning in young cattle during the month. On four of the farms the source was found to be the usual accumulator battery. On one premises the source was not located. Athlone confirmed lead poisoning on two farms during the month. A yearling bullock found dead in the field was presented to Dublin. The findings included generalised petechial and ecchymotic haemorrhages throughout the body (figure 1), most likely due to disseminated intravascular coagulation (DIC). Acute periacinar necrosis, usually seen in toxic or anoxic conditions, was seen on histopathological examination of the liver. Although the liver copper was within normal limits, the level of copper in the kidney (0.52mmol/kg) was almost three times the normal level (0.06-0.18mmol/kg). The bullock had been put through a copper sulphate footbath the day before it died and it is assumed that the animal drank some of the foot dip. A presumptive diagnosis of acute copper toxicity was made. Cork received liver tissue taken from a cow, the fifth to die from a herd of ten. The clinical signs that preceded death featured depression, inappetance, tenesmus and blindness. Histopathology showed lesions consistent with ragwort poisoning.
Kilkenny isolated Pasteurella multocida from a milk sample of a cow described as showing curds in milk at start of milking but with no palpable firmness of the udder. The bulk somatic cell count (BSCC) was normal. Sligo carried out investigations on two dairy farms with BSCC problems. In the first herd (a 160 cow herd in the process of expansion) foremilking as an aid to early mastitis detection was not practiced, and chronically infected cows were being retained. At the time of the visit, up to 25 cows had elevated SCCs. Identifying and culling chronically infected cows, foremilking, and early treatment of clinical cases were amongst the main recommendations. The second herd consisted of 50 cows. There had been a sudden rise in BSCC. Five or six cows appeared to account for over 60% of the BSCC. The main finding in this herd was over-milking resulting in teat end damage and hyperkeratosis. This damage can lead to the teat seal becoming more permeable to bacteria.
Sheep Athlone diagnosed pulpy kidney disease in two thirteen-week old lambs. In another case, Athlone examined a six-month old lamb with a history of sudden death. Gross findings included congested lungs with consolidated apical lobes. Culture of the lung yielded Mannheimia haemolytica.
Athlone examined a ewe with a history of sudden death. Postmortem examination revealed pulmonary congestion and very watery intestinal contents. Culture of lung, liver and faeces yielded Salmonella typhimurium. Appropriate advice was given regarding the zoonotic nature of this pathogen. Sligo has observed high faecal egg counts in a number of adult sheep presented for examination. Questions were raised over worming protocols and possible anthelmintic resistance.
Poultry Cork investigated a high mortality problem in a batch of five-week old broiler breeder chicks. Lesions found included haemorrhagic-mucoid enteritis involving the mid small intestine, and haemorrhage in the caecal tubes. Both of these lesions are associated with the early stages of coccidial infection. The chicks had been given an oral coccidial vaccine in the second week of life, but this coincided with a management mishap during which the water supply had been interrupted, leading to dehydrated birds. It was postulated that this event might have compromised the efficacy of the vaccine.
Peritonitis in broiler breeders just after the commencement of lay was attributed by Cork to be largely due to vent-pecking.
Other Species A strangulating umbilical hernia involving the caecum was diagnosed in a two-week old foal submitted to Sligo. Gross postmortem examination of a one-month old foal examined by Athlone showed diffuse enteritis with multiple small white spots on the mucosa of the large intestine. Salmonella typhimurium was isolated from the liver and faeces. Appropriate advice was given regarding the zoonotic nature of this pathogen. Limerick diagnosed impaction of the colon in a six-week old foal that had just returned from stud. The foal had been away for three weeks and was noticed to have lost condition and was teeth-grinding on arrival back at the home farm. The faeces were dry and chalky but the temperature was normal and the foal seemed bright and alert. Treatment for gastric ulceration was given, but the foal deteriorated over night and died the following day. The impaction was at the pelvic flexure and the contents had a sandy texture (figure 2). Kilkenny suspected that listeriosis caused the death of a three-month old cat based on the histopathological lesions seen in the brain. The cat was presented to the practitioner in right lateral recumbency with its head bent back.
Kilkenny examined a seven-month old rabbit, the second death within a week. Numerous small haemorrhages were seen on the lung (figure 3), and histopathological examination showed extensive liver necrosis suggestive of rabbit haemorrhagic disease (RHD).
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Figure 1