Current Findings in the Regional Veterinary Laboratories
June 2004
Cattle
Salmonella dublin and Pasteurella multocida were isolated from one of three calves submitted to Dublin from a
herd with a history of non-responding chronic pneumonia in several calves. Purulent cystitis was seen in another
calf from the same herd. Salmonella dublin was isolated from a number of tissues taken from a young calf
submitted for necropsy to Sligo. The Zinc Sulphate Turbidity Test (ZSTT) level for absorbed immunoglobulins in
the calf was nine units and inadequate. A three-month-old calf was submitted to Kilkenny for post-mortem
examination. It had been found dead by the owner. An acute diffuse oedematous abomasitis (see Figure 1) was
identified. This was a severe lesion that affected the entire abomasal wall. A lot of sand and grit was noted within
the abomasal folds and the physical irritation may have been a contributory factor in facilitating the invasion of
Clostridium sordelli, which was identified by Fluorescent Antibody Test (FAT). Coincidently Mannheimia
haemolytica was isolated from the lung even though pneumonia was not noted on gross examination. Kilkenny
have seen a number of cases of oedematous abomasitis where Pasteurella spp. was isolated on culture of the
abomasal wall.
Cork received an eight-week-old calf for post-mortem with suspect blackleg (Clostridium spp.) infection. It had
been vaccinated for blackleg five days previously. Findings at necropsy included a grapefruit-size abscess on the
left side of the neck, a small area of odourless haemorrhage/necrosis in the muscle on the dorso-cranial right side of
the neck and petechial haemorrhage in the thymus. No significant isolate was identified on cultures from the
abscess and Clostridia tests performed on samples from the damaged muscle were negative. Kidney Lead
concentration of 350 µmol/kg (acceptable range 0-24 µmol/kg) established lead poisoning as the cause of death and
the herdowner was advised to search for the source of lead. Sligo diagnosed a number of cases of lead poisoning.
They had a history of hyperexcitability, incoordination, impaired vision - and finally recumbency. Gross
examination in one of the cases revealed a ‘fish flesh’ type musculature. The renal cortex in that case contained
130 mol/Kg lead. Two three-month old calves with a history of nervous signs were submitted to Kilkenny for
post-mortem examination. There were no significant lesions on gross examination. The brain of one of the calves
fluoresced under ultraviolet light. Histological examination showed extensive lesions of Cerebro Cortical
Necrosis (CCN) in one of the calves and less severe lesions in the second calf. Cork diagnosed “water poisoning” excess intake of water - in a ten-week-old calf. The calf had both the haemolytic and pulmonary form with death
from suffocation due to the lung oedema. Other calves in the group had haemoglobinuria but recovered. The
group were out on grass for one week and were still being bucket-fed milk twice a day. It is thought that the
novelty of discovering the trough with available water resulted in over-drinking. A three-month-old calf that was
unable to stand for one week before being put to sleep was submitted to Limerick RVL. Lesions consistent with a
diagnosis of white muscle disease were seen in the musculature of the hind-quarters. Histopathology confirmed the
diagnosis. Interestingly, the kidney selenium level of 5.47 μmol/kg was just within the normal published range
(5.0-20.0 μmol/kg). Kilkenny diagnosed several cases of parasitic bronchopneumonia (Hoose) during the month.
A number of these cases had been treated for bacterial/virus pneumonia but failed to respond to the treatment.
Faecal examination also identified high strongyle egg counts. It serves as a timely reminder to ensure that a correct
anthelmintic programme is put in place for calves. Ragwort poisoning was suspected following histopathological
examination of a section of liver submitted to Limerick RVL. The liver was taken from a two-year old bullock that
had died quite quickly following the onset of clinical signs.
101 bovine milks for cases of mastitis were submitted to Limerick RVL during the month of June. 63 cultured
positive for Staphylococcus aureus, 17 for Streptococcus dysgalactiae, 9 for coliforms, 3 for Pasteurella multocida,
2 for Streptococcus uberis, 2 for Bacillus spp. and 5 had no significant growth. Limerick RVL investigated another
suspect outbreak of bovine botulism on a dairy farm, adjacent to a poultry unit. Four animals were affected, one
of which was found dead. The other three were showing the classical signs of flaccid paralysis. These three were
euthanised. Another case in a heifer on the same farm two weeks later was not severe, and the animal eventually
got up after ten days of careful management. An epidemiological investigation concluded that poor poultry carcass
management on the neighbouring poultry farm may have been associated with the outbreak.
Sheep
A one-month-old lamb that died suddenly showing signs of anaemia was submitted to Sligo RVL for post mortem
examination. According to the owner it was in ‘good health the evening before’. Gross examination revealed a well
preserved but anaemic carcass. A haemorrhagic abomasitis was evident. Tissue smear subjected to Gram Stain
resulted in positive bacilli being identified. Clostridium sordelli was evident on FAT following impression smears
from the abomasal mucosa. A six-week-old lamb that was found dead in the field was submitted to Kilkenny for
post-mortem examination. There was acute consolidated pneumonia of the cranioventral 50% of the lungs. The
most striking finding was the extensive oedematous and fibrinous pleurisy. Mannheimia (Pasteurella)
haemolytica was isolated on culture. Kilkenny diagnosed parasitic gastroenteritis and nephrosis in a two-month-old
lamb that had a severe tarry coloured scour and pale and enlarged kidneys. Histology confirmed severe nephrosis.
Faecal examination identified 10,500 strongyle eggs per gram. Branhamella spp (formerly Moraxella) were
isolated by Dublin from swabs collected from the conjunctivae of five ewes from a flock of sheep experiencing
an outbreak of conjunctivitis.
Pigs
Salmonella typhimurium DT104 was isolated from multiple organs of two bonhams submitted to Cork from a herd
with a problem of piglets not thriving after weaning. In addition, Pasteurella multocida was also isolated from the
lung cultures of one of the pigs while the other had a light infestation with coccidiosis confirmed.
Horse
Cork received a two month-old foal, which had been found dead, for post-mortem. Necropsy showed enlargement
and abscessation of mediastinal lymph nodes with marked purulent pneumonia. Gamella spp. (a
vancomycin/ampicillin resistant Streptococcus viridans) was isolated from mediastinal lymph node cultures and
Streptococcus equi zooepidemicus from lung cultures. Streptococcus equi subspecies equi was isolated by Limerick
from a swab taken from a perianal abscess of a two-year old mare. The mare had been covered by a stallion two
months previously and it was suspected that the mare might have picked up the infection at that time. Sligo RVL
reported sudden death of a three-year-old filly. Acute gastric dilation and rupture was identified on post-mortem
examination.
Birds
Dublin investigated an acute disease outbreak in a pigeon loft, characterised by diarrhoea, weight loss,
inappetence and central nervous signs in young, unvaccinated birds. Six out of nineteen birds died with another five
showing marked central nervous signs (see figure 2). Gross post-mortem examination confirmed that the birds were
severely emaciated and had diarrhoea. Histopathology revealed focal inflammatory brain lesions, diffuse
congestion of the liver and nephritis. Diagnosis of Paramyxovirus (PMV1) infection was confirmed by virus
isolation from brain and intestine. Two eight-week-old free-range goslings submitted to Limerick RVL were found
to have impaction of the proventriculus and gizzard. Both birds had stopped eating, had weakened and died. The
impacted material was indigestible, coarse, stemmy grass, and was unsuitable for young geese. The owners were
advised to move the remaining birds onto younger, fresher grazing.
Dog
Formalin-fixed tissue samples (lung and kidney) were submitted to Cork from a four-year-old hunting terrier dog
for histopathological examination. The dog had had inappetence for two months, lost weight and eventually died.
Two years previously the dog had been treated for swollen lymph nodes. Granulomatous pneumonia and
nephritis was seen on sections examined and Ziehl-Neelsen stains confirmed the presence of numerous acid-fast
bacilli. TB culture was not possible, as fresh tissue was not submitted. The appropriate human and animal health
authorities were notified. Subsequently a ten-month-old companion dog was euthanised. No lesions suggestive of
TB were seen in the companion dog at post-mortem but samples were taken for TB culture and histopathology.
Figure 1 - "Oedematous abomasitis in a three-month-old calf - photo Pat Kelleher"
Figure 2 - “Paramyxovirus (PMV1) infection in a pigeon – photo Dublin RVL”