Current Findings in the Regional Veterinary Laboratories
February 2005
Cattle
Athlone, Cork, Dublin, Limerick and Kilkenny all reported abortions associated with Salmonella dublin, Arcanobacter pyogenes, Bacillus licheniformis and Neospora caninum.
Mortierella wollffii was isolated from the abomasal contents of a bovine foetus submitted to Sligo. This agent is a rare but recognised cause of mycotic placentitis and abortion in cattle.
Sligo investigated an abortion storm in a 35 cow dairy herd where 11 cows aborted. Of the samples submitted, six had detectable Neospora caninum antibody titres (dam serum and foetal thoracic fluid) and Bacillus licheniformis was cultured from the foetal stomach contents of each of these. Arcanobacter pyogenes was also isolated from one foetus. Blood taken from the farm dog was found to be Neospora caninum antibody positive.
A full-term calf that had died very soon after birth and was submitted to Cork was found to have incomplete skin coverage (figure 1). The defect appeared like that of the extreme form of the genetic autosomal recessive condition of Epitheliogenesis imperfecta. The skin where present was thin and lightly haired. A detailed histopathological description of the condition can be found in the Journal of Veterinary Medicine (2004) A51: 409-412. The sire was a British Friesian bull (now deceased) that had stood in a local Artificial Insemination (AI) centre.
Kilkenny examined a seven-month old weanling, the third death on the farm with signs of abdominal pain. The animals had been on a diet of poor quality hay. Ragwort poisoning was suspected. Post-mortem examination showed oedema of duodenal and colonic mesentery. The diagnosis was confirmed following histopathological examination of sections of the liver. Limerick also diagnosed ragwort poisoning, this time, in a cow from a suckler herd in Clare. Around ten adult cattle from the same herd had died from the condition after eating contaminated silage in early 2004. The farmer had decided not to cut silage from these fields last summer. He applied selective herbicide to the pastures in June 2004 and retained the land as winterage. No grazing took place until December 2004. Deaths recommenced in Jan 2005. It is suspected that the application or efficacy of the herbicide may have been at fault.
Sligo reported a large outbreak of Psoroptic mange in housed cattle in a 60 cow suckler herd which also winters about 40 young stock in open yards with self-fed silage and access to cubicles. A Charolais bull was presented to a veterinary practitioner in very poor body condition before Christmas, showing signs of a severe dermatitis with a dorsal distribution. Photosensitisation was suspected on clinical examination, and the bull was housed in a darkened shed, where he died a few days later. There was no post-mortem examination. This herd does not routinely buy in cattle, the last animal entering the herd being this Charolais bull (Irish-bred), in 2002. In early February, the practitioner was called to six cattle showing a similar type syndrome. He suspected psoroptic mange, took skin scrapings and found large numbers of Psoroptes-like mites and submitted them to Sligo, where Psoroptic mange was confirmed. 40 - 50 cattle were affected in total. The animals have shown considerable clinical improvement on a regime of repeated moxidectin injections and cypermethrin washes.
Dr. Tom Murphy, Abbotstown (01 6072782) is anxious to examine suspected cases of congenital bovine neosporosis. He would be interested in examining any calf born to a dam antibody positive for Neospora caninum and showing congenital nervous signs, particularly hind limb ataxia.
Sheep
Athlone reported toxoplasma abortion in lamb fetuses from a number of flocks. Titres as high as 1/2048 were recorded. Dublin also diagnosed toxoplasmosis in two abortion outbreaks. Cork isolated Aspergillus fumigatus from the placenta submitted with a set of aborted lambs. It was the fifth abortion in a flock of ninety ewes. Culture of stomach contents was negative.
Sligo confirmed sheep scab in wool and skin scraping samples from three sheep that were presented at a local abattoir for slaughter. Severe skin lesions were noted at ante-mortem inspection and the animals were sampled by the veterinary inspector-on-duty. Trauma and contusions caused by scratching led to trimming of parts of the carcasses. Limerick also diagnosed sheep scab, following the submission of skin scrapings from a flock in Galway.
Sligo reported an outbreak of urolithiasis in housed wether lambs. Six died, two of which were submitted for post-mortem examination. These lambs had complete urinary obstruction, with sand-like (sabulous) uroliths obstructing the urethra at the tip of the penis. The history revealed that the group was receiving a large amount of concentrates without free access to fresh clean water. The company that supplied the feed is investigating. Urolithiasis has become a perennial problem in fattened lambs, and some feedlots now only buy in female store lambs, which have a much lower incidence of the problem because of their shorter wider urethras.
A large abscess taken from the mediastinal lymph node of a sheep at routine abattoir inspection was submitted to Kilkenny for culture. Caseous lymphadenitis was diagnosed following the growth of Corynebacterium pseudotuberculosis. The abscess was described as caseous off-white, green-tinged pus surrounded by a thin fibrous capsule.
An adult ewe with a history of nervous signs was presented to Sligo. Arcanobacter pyogenes was cultured from the brain and bacterial encephalitis was evident histopathologically. Athlone diagnosed listeriosis in a ewe that had been unsuccessfully treated for pregnancy toxaemia. Routine culture did not yield the organism but histopathological examination of the brain lead to the presumptive diagnosis being made. Mid-brain microabscesses were also detected by Dublin in two ewes taken from a flock of housed sheep, of which thirty had died. Listeria monocytogenes was isolated from the spleen of one of these ewes.
Athlone reported that an infestation with Damalinia ovis (biting louse) had caused problems in a flock of ewes.
Pigs
Limerick RVL diagnosed post-weaning Escherichia coli enteritis in four-week old bonhams. Cork isolated haemolytic Escherichia coli G205 from two seven-week old weaners in the one herd. Severe haemorrhagic enteritis, hydropericardium and congested lungs were seen on post-mortem examination.
Two two-year old boars that died on the same day in the same breeding herd were found on post-mortem examination in Cork to have died as a result of gastric ulceration. One had a perforated ulcer with leakage of contents to the peritoneal cavity and a resulting peritonitis. The other had haemorrhaged from its ulcer into the stomach lumen and died from anaemia.
Poultry
Yolk sac infection and starveouts were confirmed by Cork in young turkeys with high mortality in the first week of life. They came from a unit of twenty thousand birds, destined for the food trade. More significantly, Salmonella indiana was identified in the flock. The relevant public health bodies were notified because of the zoonotic potential of the isolate.
There was increased mortality and reduced egg production in a broiler-breeding unit in the Cork region. All birds submitted had gross lesions and bacterial confirmation of acute colibacillosis. There was a good response to the therapy advised by the practitioner based on Cork RVL bacteriology findings.
An outbreak of infectious sinusitis in a turkey flock investigated by Dublin was attributed to Mycoplasma gallisepticum. The diagnosis was confirmed by Bacteriology Division, CVRL following detection of antibodies using a highly specific blocking ELISA. Clinical signs included severe periorbital sinusitis, nasal discharge, coughing, sneezing, and consequent dyspnoea, lethargy, inappetance and failure to thrive, all of which are characteristic of Mycoplasma gallisepticum infectious sinusitis in turkeys (Figure 2). Mortality reached about 25% in affected birds. Over eighty percent of birds in a flock of about 100 were affected. Mycoplasma gallisepticum infection of poultry is a Class A notifiable disease which can be vertically transmitted in eggs even through hatcheries and for this reason all chicken and turkey breeding flocks in the Republic of Ireland are monitored serologically to ensure they are clear. Good biosecurity against contact with wild birds and purchase of eggs or chicks only from (serologically monitored) Mycoplasma-free parent flocks are the basic steps to prevent entry of infection into a flock.
Other Species
Kilkenny diagnosed non-suppurative encephalitis in two unrelated greyhounds, five and seven months old. A littermate of one of these dogs had been euthanased a few days earlier, with similar signs. The condition had been previously diagnosed on the premises. The dogs had been sick for about three weeks. Nervousness and weight loss were the first signs observed. One dog tended to stand in a corner but was not head pressing. The other had become aggressive to other dogs and had proprioceptive defects in hind limbs. He often yelped when picked up. This condition is identical to that reported by Callanan et al. in Veterinary Pathology (2002) 39: 56-65.
Dublin diagnosed winter inanition of farmed fallow deer. The deer on necropsy had serous atrophy of fat stores and generalised emaciation. Tissue copper and selenium concentrations were extremely low. The rumenal contents had a very low pH. These deer had continuous light due to a broken light switch. This is likely to have affected feeding patterns, resulting in a background acidosis problem. When the switch was fixed and supplementary beet pulp, copper and selenium were added to the feed, the deaths ceased.
CAPTIONS FOR PHOTOS
Figure 1 “Epitheliogenesis imperfecta in a full-term calf- photo Pat Sheehan”