Current Findings in the Regional Veterinary Laboratories
February 2008
Cattle
502 calf faecal samples were examined during the month. Figure 1 illustrates the
findings. All centres reported a high prevalence of rotavirus infection. 158 blood
samples from calves less than ten days of age were analysed using a zinc sulphate
turbidity (ZST) test. Figure 2 illustrates the findings. 64% of the samples had
readings of less than 20 units, suggesting that these calves had not taken enough
colostrum and were immunocompromised.
Kilkenny isolated Salmonella typhimurium from calves 4 to 6 week old calves
presenting clinically with ill-thrift. Diarrhoea was not a consistent presenting
sign and pneumonia was not reported. The zoonotic implications of the disease were
discussed with the veterinary practitioner.
Infectious bovine rhinotracheitis (IBR) was diagnosed by Kilkenny as the cause of
death of a two-month calf with a history of acute pneumonia. A seven-month old calf
examined by Athlone had severe lesions of pneumonia, with areas of emphysema in
the cardiac lobes and diffuse abscessation of the lung parenchyma. Culture of the lung
was positive for Mycoplasma bovis.
Dublin examined a yearling heifer that had died after an acute episode of
enteritis. It had been bought-in a sort time beforehand. Numerous small inflammatory
foci were seen in the abomasal mucosa and lesions of mucous enteritis in the terminal
ileum. Bovine viral diarrhoea (BVD) viral antigen was detected from both this heifer
and a subsequent one that died with a similar clinical history.
Kilkenny examined two ten-month old weanlings that had been losing weight over a
few weeks and had developed diarrhoea in the final week of life. Post mortem
examination revealed a very heavy fluke infestation, which had severely damaged
the liver. Salmonella dublin was also isolated. Dublin diagnosed bacterial
thromboembolism in a yearling limousin steer that was found dead in a slatted unit.
Emboli were seen in the kidneys, lungs and central nervous system with associated
clumps of bacteria. Staphyloccocus aureus was isolated from various tissues,
including the meninges. A yearling heifer was submitted to Athlone with a history
of sudden death. The farmer reported that the heifer had been perfectly healthy less
than an hour before death. On gross examination, a three-inch diameter abscess was
found in the interventricular septum of the heart, communicating with the right atrium
(figure 3). Actinomyces pyogenes was cultured from the abscess.
A thirty-month old Friesian cow was presented to Dublin with a history of depression
and pyrexia that developed three days after calving. The symptoms progressively
worsened over the following three weeks, ending in recumbency and death. On post
mortem examination the peritoneal cavity was filled with foul smelling brown fluid,
and a thick layer of fibrin was attached to the serosal surfaces of intestines and
abdominal organs. The source of the fluid was a massive ruptured abscess attached to
the rumenal wall. Opening of this abscess revealed large floccules of inspissated pus
and a steel wire seven centimetres in length. The overall interpretation of these
findings was traumatic perforation of the rumenal wall by a steel wire with
rumenal wall abscessation discharging into the peritoneal cavity with resultant
development of a diffuse fibrinous peritonitis.
A botanist from the National Botanic Gardens identified a plant submitted to Sligo as
the common privet (Ligustrum vulgare). This plant is commonly used as a hedging
plant and was present in the field where two adult cows had died suddenly. While
poisonings are rare, the plant is known to be fatal. Its manifestations include colic,
staggering and death within four to 48 hours of eating the plant. Ruminants are most
likely to consume such vegetation only when other forage is scarce.
Sheep
Two foetuses were submitted to Athlone from two separate ewes on the same farm.
Listeria monocytogenes was cultured from the stomach contents of both foetuses, and
one was also positive for Chlamydophila abortus (enzootic abortion of ewes). Both
pathogens are significant zoonotic agents, particularly of danger to pregnant
women. The veterinary practitioner gave the appropriate advice to the flock owner.
Kilkenny diagnosed Salmonella dublin and EAE as the cause of ovine abortion in
different flocks.
Four neonatal lambs were submitted to Dublin from a flock with a high lamb
mortality rate for a number of years. Lambs at one to two days of age typically
showed signs of depression, which progressed to death at three to four days of age.
While gross post mortem examination revealed milk in the abomasum, intestinal
contents were scant. Blood ZST levels were normal in one, well below normal in the
second and at extremely low levels in the remaining two. Histological examination of
tissues revealed depletion of brown fat around internal organs in all cases, an indicator
of malnutrition. The overall findings suggested that malnutrition (perhaps
involving mismothering) was contributing to the mortality problem in these
lambs. Kilkenny diagnosed coronavirus as the cause of enteritis in a group of five-day
old lambs with diarrhoea.
Sligo diagnosed parasitic gastroenteritis involving Trichuris ovis infestation in a
flock of ill-thriving out-wintered yearling lambs. The long whip-like tails of the
tricurids were readily identifiable in the fluid bowel contents. February saw another
peak of deaths in sheep due to fascioliasis. In chronic, active infestations sudden
deaths are often seen by shepherds during flock handling or movement. Invariably
these were attributed to internal haemorrhage associated with rupture of a friable
liver.
Other Species
Streptococcus zooepidemicus was isolated by Dublin from an aborted equine foal
with plaque like lesions on the umbilicus.
A young horse with a history of ataxia was euthanased and submitted to Limerick.
No gross lesions were seen but histopathology of the cervical spinal cord showed a
focal area of purulent meningitis with intra-lesional calcification. The aetiology of
the lesions was not determined. Limerick diagnosed diaphragmatic hernia with
haemorrhage into the peritoneal and pleural cavities of a heavily pregnant mare that
was found dead.
A five-year old Border Collie was out herding sheep before returning to the farmer
with dyspnoea and "whitish lips". It collapsed within a short time and was dead within
an hour. He hadn't been fed the day before because the farmer was away. On gross
post mortem examination there was evidence of massive haemorrhage from the base
of the aorta, along the fascial plane and into the thoracic cavity. Haemorrhage was
also present in the axillary region with partial clotting. There were no other findings
to suggest poisoning as the cause of the haemorrhage. Aortic rupture was suspected.
This has been rarely reported in the literature as a spontaneous occurrence in
Border Collies.
Alphachloralose poisoning was detected in a group of birds presented to Sligo. The
National Parks and Wildlife Service had submitted the birds, which had been found
on a lake shore. The group consisted mainly of ducks and jackdaws. The wildlife
ranger had recovered some live, comatosed ducks and had revived them by keeping
them warm.
CAPTIONS FOR PHOTOS
Figure 1
Figure 2
Figure 3
“Abscess in the cardiac septum of a heifer- photo Gerard Murray”