Current Findings in the Regional Veterinary Laboratories
February 2006
Cattle
BVD virus antigen was detected in an aborted bovine foetus submitted to Dublin from a herd for
which there was a history of one previous abortion in December.
Limerick examined a full-term stillborn calf and found a large, long-standing, diaphragmatic
hernia with distended forestomachs compressing the lungs into the cranial part of the thoracic
cavity. Sligo examined a four-day old calf that died from progressive circulatory failure. There was
a large cardiac septal defect. Limerick also reported on an atrial septal defect (persistent foramen
ovale) in a five-day old calf that died following a period of respiratory distress. Cork had a number
of calves from different sources with atresia of the intestines. In one calf with colon atresia the anus
was patent and the rectum was four centimetres in length. The caecum and part of the ileum were
distended with faecal material.
A two-day old calf with a history of weakness since birth was presented to Kilkenny. Pulmonary
oedema, congestion and a fibrinous peritonitis were seen on gross examination. The abomasal wall
was also oedematous and the mucosal surface was haemorrhagic (figure 1). Pasteurella multocida
was isolated from liver, lung and abomasum. A zinc sulphate test (ZST) gave a reading of only six
units. Poor colostrum absorbtion was also suspected as being a major factor in the development of
septicaemic listeriosis in a week-old calf seen by Limerick. The calf was found dead. Other than
visceral congestion gross lesions were unremarkable. The ZST test reading was four units. A fourday old calf submitted to Athlone was found to have jaundice, enlarged oedematous lungs,
hepatomegaly, and a fibrinous pericarditis. Salmonella dublin was isolated from multiple organs.
Three of four purebred Charolais calves, the result of embryo transfer and delivered by caesarean
sections died within hours to days on a farm in Tipperary. Two of these were submitted to the
Limerick for post-mortem examination. Both had a history of weakness, drowsiness and
inappetence. The most obvious lesion seen in both calves was anaemia. The two calves were
positive for bovine viral diarrhoea (BVD) virus on ELISA. The fourth calf that survived
developed a navel infection and joint ill. A serum BVD antigen test carried out on this calf was
positive. Euthanasia was recommended. Investigations are ongoing into the source of the infection.
Kilkenny examined a four-month old weanling with a history of pneumonia. Pasteurella multocida
was isolated from the lungs. Tissue samples were also found to be positive for BVD antigen. Sligo
diagnosed a case of mucosal disease in a weanling with a history of enteritis and weakness. Gross
lesions included linear ulcers in the oesophagus. Ulcers were also found in the rumen and between
the digits of the right foreleg. BVD virus was identified from a serum sample.
Clostridium septicum (malignant oedema) was isolated on anaerobic culture, and confirmed by
fluorescent antibody test, in the fifth fatality of a group of one-week old calves. Two of the calves
had been presented to Cork for post-mortem. They were in good body condition and showed similar
gross lesions- severely distended carcass (figure 2) with accumulation of blood stained exudates
and gas in the subcutaneous interfascial spaces and muscle (cellutis/myositis). Both calves were
being treated for an ongoing omphalitis (mild in one calf, severe in the other and complicated with
fibrinous peritonitis), either suggesting umbilical or iatrogenic route of entry. Kilkenny encountered
Salmonella Dublin-associated terminal dry gangrene in a number of calves less than one month of
age from two different herds.
Athlone reported lead poisoning in two-month old suckler calves. Two calves were submitted,
both of which died without any signs being noticed. Very high levels of lead were detected in the
kidneys. On investigation it was discovered that the calves were bedded on peat that came from a
bog where clay pigeon shooting was practiced. Calculations revealed that over three tons of lead is
deposited on the shooting surface annually.
Pyelonephritis was observed by Dublin in a six-month old calf, which had a history of acute scour.
On gross post-mortem examination, the kidneys were enlarged with numerous small white
lesions evident particularly in the cortex. Histopathological examination revealed suppurative
tubulointerstitial nephritis. A weanling bullock was presented to Sligo with a history of severe
respiratory distress. It had been treated unsuccessfully for pneumonia. Gross post-mortem
examination showed large numbers of nodular lesions diffusely distributed throughout the lungs.
Histopathological examination lead to a diagnosis of thymic lymphosarcoma.
Histopathological examination of a skin biopsy taken from a heavy store bullock and submitted to
Sligo lead to a diagnosis of cutaneous lymphoma. Round, circumscribed lumps had appeared all
over the animals back quite suddenly the previous week. The size of the lumps varied from one to
five centimetres in diameter. Kilkenny diagnosed pericarditis in a bullock with a history of illthrift. Approximately four litres of watery pus was present in the pericardium. The reticulum was
adhered to the diaphragm and there were lesions of localised peritonitis, suggesting the likelihood
of a traumatic reticulitis being the ultimate cause. No wire or sharp object was found. Arcanobacter
pyogenes was isolated.
Sheep
A lamb was submitted to Sligo following sudden death. Two other lambs from a group of thirty had
already died. The only significant finding at post-mortem was the presence of Pieris japonica
leaves in the rumen of the lamb. Pieris species are in the same family as rhododendron. The leaves
are bitter and sheep will only eat them when all other food sources are scarce. This plant seems to
be at least as poisonous as rhododendron, but awareness of the risk is much lower. Kilkenny
diagnosed listeriosis in a group of six-week old lambs.
Sligo investigated an outbreak of urolithiasis in Texel rams, following the post-mortem diagnosis
of urolithiasis in two rams from the flock. The outbreak occurred at pasture. The rams were fed
concentrates. Falling grass cover, (effectively increasing the proportion of concentrate in diet) and
once a day feeding of concentrates were considered at the main contributing factors to the
development of the outbreak. Once a day feeding of concentrates was considered to have led to
periodic gorging, which in turn led to periodic rumenal acidosis, which facilitates urolith formation.
Pigs
Sligo diagnosed lymphosarcoma in a Gloucestershire Old Spot boar. The boar was eight months
old, from a pet farm. The animal initially showed clinical signs two to three days prior to dying.
These signs consisted of lethargy, vomiting and marked weight loss. Gross lesions included
hepatomegaly, jaundice, gastric ulceration and enlargement of the mesenteric lymph nodes.
Examination of the kidneys revealed chronic renal failure.
Swine dysentery was presumptively diagnosed by Cork when significant numbers of spirochetelike bodies were observed on the victoria-blue stained faecal smear of two finishing pigs with
fibronecrotic enteritis of the large intestine. Serpulina hyodysenteridae is the causal agent of swine
dysentery
Other Species
All laboratories reported a sharp rise in the number of bird submissions in line with the increased
media and public interest in the spread across Europe of the H5N1 avian influenza virus. The large
variety of species presented included pheasants, ducks, gulls, pigeons, herons, moorhens, gannets, a
parrot, and many swans. Appropriate samples for avian influenza testing were collected, all of
which yielded negative results. A greater rate of submissions occurred during the periods of very
cold weather which was considered to have been played a role in the death of some of the birds,
some of which had very little or no body fat reserves and even muscle tissue atrophy in some cases.
Signs of trauma, predation and even gunshot wounds were evident in some other cases.
Kilkenny diagnosed psittacosis in a recently imported parrot. A number of pigeons were submitted
to Limerick from a public car park in Ennis where their deaths had caused some public disquiet.
Some were found dead, others were in a stupor, and some even appeared to have dropped dead from
the sky. Grain was found nearby and malicious intent was suspected. Alphachoralose poisoning was
suspected but tests were carried out to rule out avian influenza. Toxicological analyses on
crop/gizzard contents and suspect feed were found to be positive for alphachoralose. The gizzard
contents showed toxic levels (40 micrograms per gram). The grain, which had been leached by rain,
showed lower levels (2 micrograms per gram).
CAPTIONS FOR PHOTOS
Figure 1 “Haemorrhagic appearance of the abomasal mucosa in a calf with Pasteurella multocida
septicaemia– photo Donal Toolan”
Figure 2 “Severely distended carcass of a calf with malignant oedema – photo Pat Sheehan”