Current Findings in the Regional Veterinary Laboratories
AUGUST 2006
Cattle
Kilkenny examined a three-month old calf with a history of pneumonia. There was pleurisy and
severe consolidation of the lungs, primarily involving the cranial lobes. Miliary necrotic lesions
were seen in the apical lobes. Arcanobacterium pyogenes was isolated. Athlone carried out a
post-mortem examination on a four-month old calf with a history of ill-thrift and recurring episodes
of clinical illness. Diffuse pneumonia was seen and culture yielded a growth of Mannheimia
haemolytica. Abomasal ulceration and chronic nephritis were also noted. A Bovine Viral Diarrhoea
(BVD) virus isolation test was positive
Cork isolated Clostridium septicum on anaerobic culture from a four-month old calf with
advanced carcass decomposition, extensive and diffuse subcutaneous crepitation and
emphysematous reddish-black friable skeletal muscles mainly affecting the neck region. Three
animals died with similar symptoms over a 48-hour period.
A four-month old calf was submitted to Athlone from a herd in which there was a diarrhoea
problem in calves around this age. Gross post-mortem examination showed gastro-intesinal
ulceration (suggestive of BVD infection) and liver infarction. The lesions in the liver resembled
those associated with black disease but fluorescent antibody tests (FAT) for various clostridial
species were all negative. Histopathological examination showed widespread thrombosis with
fungal hyphae evident. A fungal septicaemia was present which may have been a secondary,
following intensive antibiotic therapy. The histopathological changes were also suggestive of BVD
involvement. All laboratories reported cases of bovine coccidiosis. Analyses of the figures shows
that, despite a drop in the number of faecal samples submitted during the month of August, there
was a continuing increase in the percentage of samples positive for coccidial oocysts (figure 1). The
dry weather conditions may have had an effect on this. With poor grass growth, calves have been
held in paddocks for longer and have been receiving extra concentrate supplementation. It is likely
that these management practices have lead to an increase in the number of oocysts in the
environment.
A six-month old calf was submitted to Cork with a history of severe respiratory distress and
subsequent death. Post-mortem examination revealed paleness of the skeletal musculature, a large
haematoma with associated bruising and oedema occupying the ventral half of the neck and
extending from the intermandibular area to the heart. Both the trachea and oesophagus were
undamaged. Histological examination revealed diffuse suppurative myositis, panniculitis, and
fibinous pericarditis. No bacterial growth was obtained from the samples taken.
A six-month old calf was submitted to Athlone having died showing nervous signs and blindness. It
was the third of this batch to die within two days, and the fourth in a month. At gross post-mortem
examination haemorrhages were evident in the thymus, trachea and on the surface of the kidney.
Biochemical analysis of the renal cortex gave a lead value of 139micromols/kg wet matter, which is
consistent with lead toxicity. The source of the lead was not identified. A field investigation was
undertaken by Limerick into a herd where calves were suffering from ill-thrift and high mortality
beginning at about the three-week old stage. A variety of conditions were found. There was
evidence of two separate episodes of viral-associated pneumonia. These were linked with
Respiratory Syncytial Virus (RSV) and Parainfluenza Virus (PI3) infections. Intestinal parasitism,
coccidiosis and polioencephalomalacia were also found. Investigations also revealed evidence of an
earlier rumen malfunction probably associated with ruminal drinking and acidosis.
Athlone isolated Salmonella typhimurium from the faeces of a cow with a history of persistent
diarrhoea. Salmonella typhimurium infection is a class B notifiable disease and is a zoonotic agent.
Athlone reported right-sided displacement and torsion of the abomasum as the cause of death of a
two and a half year old dairy cow.
Sheep
Athlone reported pulpy kidney disease and ruminal acidosis in two ten-week old lambs. Nine
similar deaths had occurred in the group. The lambs were ten days weaned and their grass diet was
supplemented with lamb pellets. Athlone reported spinal abscessation in two five-month old lambs
that presented with posterior paralysis and recumbency. Post-mortem examination revealed a spinal
abscess in the third thoracic vertebra of each lamb. Bacteriology did not yield a significant
pathogen. Athlone reported parasitic gastroenteritis as the cause of ill-thrift and diarrhoea in a lamb
flock. An anthelmintic resistance problem is suspected. Faecal egg counts of up to 1,200
strongyle eggs per gram were recorded.
Kilkenny examined a recently purchased ram that had presented clinically with inappetance,
haemoglobinuria and jaundice. A liver copper result of 4.7 mmol/kg wet matter was well above the
normal range of 0.06 to 2.50 mmol/kg. Copper poisoning was diagnosed.
Pigs
Athlone reported that porcine circovirus 2 (PCV2) was detected in pigs from two farms. Diagnosis
was by immunohistochemistry (IHC) that was carried out in the Central Veterinary Research
Laboraotry at Backweston. The clinical signs reported were wasting, diarrhoea and pneumonia. At
post-mortem examination there was evidence of interstitial pneumonia and nephritis.
Histopathological changes included lymphocytic depletion and intestinal villous atrophy.
Poultry
Limerick examined poultry from a number of small backyard flocks during the month. Most were
associated with single deaths. Chronic respiratory disease, intestinal parasitism, egg peritonitis and
smothering due to overcrowding were among the most common diagnoses reached.
Athlone diagnosed aspergillosis in a two-week old gosling, one of seven to die following signs of
inappetance and respiratory distress. Miliary nodules were seen in the lung tissue and
Aspergillus fumigatus was isolated on culture. The infection was more than likely caused by the
inhalation of fungal spores from mouldy bedding or feed. The infection of eggs in hatcheries can
also be a cause of extensive losses, leading to poor hatchability and dead-in-shell embryos.
Other Species
A three-month-old foal was examined in Athlone following a short illness and death with clinical
signs described as diarrhoea and pneumonia. Gross post-mortem examination showed emphysema
of the apical lobes of the lungs and diffuse congestion. The liver had a “mottled” appearance.
Salmonella typhimurium was isolated from multiple organs. Parasitological analysis also showed a
faecal egg count of 10,000 Strongyloides eggs per gram. A mare submitted to Cork with a history of
‘sudden death’ appeared to be toxaemic and was found to have a collapsed lung and a
diaphragmatic hernia. A loop of the colon was protruding through the torn diaphragm and this had
ruptured leading to the leakage of contents into the pleural space.
Athlone diagnosed Johnes disease in two goats that presented with a history of poor thrive.
Pigeons submitted to Cork from a loft where almost half of the flock had died over a three week
period were found to have had a severe infestation with Ascaridia spp. in the intestinal lumen,
leading to intestinal impaction. In moderate infections these worms (often Ascaridia columbae in
pigeons) are fairly well tolerated, with few clinical signs in adult birds. However, when large
numbers are present, the worms can cause intestinal occlusion and death.
CAPTIONS FOR PHOTOS
Figure “The percentage of bovine faecal samples positive for coccidial oocysts, Jan-Aug 2006”
Figure “Lobulation of the liver of a 12-year old German Shepherd bitch- photo by Donal Toolan”