Current Findings in the Regional Veterinary Laboratories
December 2005
Cattle
Bovine foetal submissions continued to be high during the month. The graph displays the isolation
rate for the most common abortefacients encountered (Figure 1). Post-abortion serology results
showed high levels of seroconversion to Salmonella Dublin and Neospora caninum amongst the
animals sampled. Preliminary examination of the data would suggest that these two pathogens
appear to be the most common agents associated with abortion in Ireland at present.
Kilkenny diagnosed colisepticaemia and hypoglobulinaemia in two two-day old calves from
different herds. Hypoglobulinaemia was also a feature in another calf that had died following a
brief period of severe abdominal pain and head shaking. The zinc sulphate turbidity (ZST) test
reading was six units (normal readings should be above 20 units), a faecal sample was positive for
rotavirus and cryptosporidia, and there was evidence of low-grade meningitis on histopathological
examination of the brain. Athlone reported chronic salmonellosis in three calves aged six to eight
weeks old. The calves presented with gangrene of the extremities involving ears, tails and legs
Figure 2). Salmonella Dublin was isolated from one calf that had not been recently treated with
antibiotics.
Lungworm infection in a weanling was observed by Dublin. This has been observed in previous
winters and serves as a reminder that farmers and practitioners should consider lungworm in their
differential diagnoses of respiratory disease, even in December. Athlone and Kilkenny both
diagnosed pneumonia in weanling cattle, associated with Manheima haemolytica. Dublin examined
two of five weanling cattle, which had died, in a group of 300. At least thirty of the animals had
been showing signs of respiratory distress. The animals had recently been purchased and the groups
were mixed prior to housing in a poorly ventilated shed. Pasturella multocida was isolated from the
lungs of both carcases.
Athlone carried out a post-mortem examination on a weanling, which had been treated with a long
course of antibiotics for an infection in the head after dehorning. Gross examination showed
multiple necrotic foci in the lungs and liver, as well as a large abomasal ulcer. Histopathological
examination showed multiple thrombi especially in the lungs. Careful examination of the thrombi
showed the presence of fungal hyphae, which is suggestive of a fungal septicaemia. A six-month
old weanling examined by Limerick was found to have severe necrotic cellulitis and myositis of
the right hind leg, extending from the coronet to the hip. The likely cause was a skin puncture
wound found in the region of the coronet. Arcanobacter pyogenes was isolated from the lesion.
The deaths over a three-week period of four housed yearling cattle on silage were investigated by
Cork. Botulism was suspected based on the clinical signs of flaccid paralysis followed by death.
Clinical pathology and necropsy failed to identify other diseases and toxin tests are pending. The
herd owner had harvested the silage from rented land on which there are broiler-rearing units.
Athlone diagnosed Johne’s disease (Mycobacterium avium subspecies paratuberculosis) in a
Charolais bull with a history of chronic diarrhoea and ill-thrift. A positive blood antibody test
(ELISA) was followed some months later by a positive faecal culture test. Based on the
confirmatory culture result, the local district veterinary office was notified.
Sheep
Athlone, Kilkenny and Sligo reported parasitic gastro-enteritis and fluke causing ill-thrift and
mortality in a number of sheep flocks. Athlone examined faecal samples from an organic sheep
flock. The samples showed moderate numbers of strongyle and trichuris eggs, but also very high
tapeworm egg counts.
Kilkenny found that a six-month old lamb had evidence of a severe dosing gun injury. A large
necrotic mass was found in the pharyngeal area, and lesions of pneumonia were also seen.
Microabscessation of the spinal cord, suggestive of listeriosis, was seen on histopathological
examination. A six-month old lamb examined by Dublin was found to have evidence of
malnutrition and cobalt deficiency. The lamb had a history of progressive ill-thrift over a period of
weeks. There were a number of other deaths with similar histories in the same cohort group.
Samples submitted to Cork from sheep sent for slaughter had evidence of both sheep scab and
ringworm. The sheep had clinical signs of pruritus on ante-mortem inspection. Ringworm is
considered to be rare in sheep but was recorded previously in Cork (Power, S. B. and Malone, A.
(1987) Veterinary Record 121, 218-220). Athlone reported lice infestation (Damalinia ovis) in a
sheep flock where scratching and wool loss was a clinical feature.
Pigs
Kilkenny isolated Streptococcus dysgalactiae equisimilis from the organs of one of three nine-day
old pigs with lesions consistent with septicaemia. This pathogen is normally associated with
superficial suppurative lesions in pigs. No external lesions were noted.
Two 35-day old piglets with a history of enteritis were submitted to Kilkenny. Both showed severe
congestive lesions of the small and large intestines, with very watery contents. Escherichia coli
0149 was isolated from both piglets.
Other Species
Athlone reported on a case of suspected warfarin poisoning in a dog. Material containing cereal
grains mixed with a blue chemical was found in the stomach. The diffuse haemorrhages seen on
gross examination were suggestive of warfarin toxicity.
Athlone reported on the deaths of 22 deer, does and fawns, found in a paddock. Post-mortem
examination of one animal showed that the cause of death was cervical fracture. A variety of other
lesions such as subcutaneous haemorrhage, skin perforations and abrasions were also described. It
was concluded that the animals had been chased and that in their terror and efforts to escape they
had killed themselves on the fences and the bushes.
Dublin was involved together with Virology Division in the post-mortem examination of five
Whooper swans from a larger flock of wild swans from which others were also either found dead
or moribund. No acute inflammatory lesions were observed and all tests were negative for
infectious viral pathogens. Four out of the five swans had impaction with either forage or some
grain of the proventriculus and in some cases the entire oesophagus and gizzard as well (figure 3).
Lesions consistent with aspergillosis were observed in the air sacs and lung tissue of one swan.
Further investigation into the aetiology (including the possibility of lead poisoning) of these
pathology findings was continuing. .
CAPTIONS FOR PHOTOS
Figure 1 “Microbiological analysis of Bovine Foetal Samples Submitted to the RVLs during
December 2005”
Figure 2 “Terminal dry gangrene associated with Salmonella Dublin infection in a two-month old
calf – photo John Fagan”
Figure 3 “Impaction of the oesophagus and gizzard of a swan – photo William Byrne”