Current Findings in the Regional Veterinary Laboratories
July 2007
Cattle
Athlone diagnosed fungal pneumonia in a three-month old calf with a history of
respiratory distress. Histopathological examination of lung tissue revealed focal
abscessation, with fungal hyphae visible. The calf had been subjected to prolonged
antibiotic treatment, which may have been significant in the pathogenesis of the
disease. Kilkenny examined a three-month old calf, with a history of intermittent
diarrhoea and weight loss over a period of one month. Hepatomegaly was a feature,
with large (three inch diameter) necrotic foci distributed throughout the liver
parenchyma (figure 1). Similar but smaller lesions were found in the reticulum,
spleen, intestine and associated lymph nodes. A systemic mycosis was diagnosed
following histopathological examination of the affected tissue.
A three-month old home-reared suckler calf was presented to Sligo. The animal had
been coughing and wheezing for five weeks prior to death, and had received a number
of treatments. Gross postmortem findings included pneumonia and bloody urine.
Bovine viral diarrhoea (BVD) virus was detected in lung tissue, and histopathology
revealed an acute suppurative bacterial pneumonia. A blood sample taken from a
four-month old calf displaying signs of poor thrive and scour was found by Cork to be
positive for BVD virus. A follow up investigation revealed that the dam (> five years
old) and her ’06 calf (a heifer) were also BVD virus positive.
In Athlone hoose pneumonia was diagnosed in a 16-month old bullock, which died
following a short course of respiratory distress. Eight animals from a group of fifty
were showing similar signs. Gross examination revealed congestion and abscessation
of the apical lobes, with large emphysematous bullae in the caudal lobes. No
lungworm larvae were visible in the trachea or bronchi and a Baerman faecal test also
proved negative. However, histopathology showed interstitial changes, bronchitis and
larvae present, confirming a diagnosis of hoose pneumonia. All other animals in the
group were treated with levamisole and a good recovery was reported.
A four-month old calf that had been dribbling urine and had ventral oedema was
examined at Kilkenny. A haematoma in the penis was found to have obstructed the
urethra (figure 2) resulting in a tiny rupture of the urinary bladder on its dorsal
midline and leakage of urine into the peritoneal cavity. Athlone diagnosed sporadic
bovine leucosis in a four-month old calf, which had died suddenly. The referring
private veterinary practitioner had identified gross enlargement of the prescapular
lymph nodes and postmortem examination revealed that these and all of the other
lymph nodes in the body were grossly enlarged. A PCR test for enzootic bovine
leucosis (EBL) was negative. Routine culture of the lung yielded Salmonella
typhimurium.
All Regional Laboratories recorded cases of blackleg in weanlings. In Athlone a
dead five-month old calf was found to have a severe fibrinous pericarditis. Clostridial
involvement was suspected and an impression smear of the pericardium was positive
for Clostridium chauvoei using a fluorescent antibody test (FAT).
Sheep
Pulpy kidney was diagnosed by Sligo in a lowland lamb submitted from a flock
where there had been several sudden deaths. The gross lesions seen included
pericardial effusion, haemorrhagic enteritis, and endocardial haemorrhages, as well as
the accelerated renal autolysis that gives the disease its name. Routine clostridial
disease vaccination has been discontinued in a number of flocks in recent years as
farmers seek to trim costs, and a number of large outbreaks of clostridial disease have
been reported. Athlone also diagnosed pulpy kidney disease during the month.
Kilkenny confirmed tuberculosis in the mediastinal lymph node of a sheep presented
to a local abattoir for slaughter. The suspect sample was submitted by a temporary
veterinary inspector (TVI) carrying out routine meat inspection duties.
Mycobacterium bovis was isolated on culture.
Athlone investigated the death of ten six-week old lambs, which occurred two days
following routine anthelmintic treatment. Gross findings included pericardial effusion,
widespread petheciation and pulmonary congestion. Large numbers of coccidial
oocysts were detected in the faeces. Histopathological examination revealed a toxic
hepatitis, and biochemical analysis of liver samples yielded cobalt values of 52, 48
and 43 micromoles per kilogram wet matter, indicating cobalt toxicity. The normal
range for liver cobalt is 0.7 to 5.0 micromoles per kilogram wet matter. It was
discovered that the anthelmintic used to treat the lambs contained a cobalt
supplement. A single dose of 40-60 mg Co/kg bodyweight, as a soluble salt, may be
fatal to sheep (Andrews 1965).
Dublin diagnosed ovine pulmonary adenomatosis (Jaagsiekte) following
histopathological examination of a formalin-fixed lung tissue sample taken from an
eighteen-month old sheep with respiratory signs and progressive ill thrift. Three other
sheep had died in similar circumstances.
Kilkenny isolated Salmonella typhimurium from a ewe that had been ill for a day or
two and was treated with calcium borogluconate. Gross findings included
hydrothorax, hydropericardium and hydroperitoneum. There was a nutmeg liver and
chronic abscesses in both halves of the udder. The faecal strongyle egg count was
high. Histology demonstrated a severe necrotising hepatitis and interstitial
pneumonia.
Other Species
Salmonella typhimurium was isolated from the tissues of three foals, submitted to
Athlone from one farm. All three were about months of age and died following an
acute course of enteritis. A farm visit identified access to a drain where “lake birds”
had been congregating during the previous month as a possible source of the outbreak.
Advice was given regarding preventing access to this drain and appropriate
disinfection on farm. This outbreak was one of 11 outbreaks that have been recorded
so far this year across a number of species that represents a significant increase on the
same period last year. Salmonella typhimurium is of particular interest due to it’s
zoonotic potential and appropriate advice was given to the herdowners in all cases.
Limerick diagnosed aspergillosis in a flock of pheasants being reared for release by
a local gun club. The pheasants were eight weeks old and had been bought in from a
hatchery/rearing facility two weeks previously. Wet weather meant that the bedding
had become saturated and that along with the warm humid weather is thought to have
lead to the fungal growth. The main signs noted were dyspneoa and ataxia.
Postmortem examination showed multiple granulomatous foci in the lungs and air
sacs. Dublin was asked to investigate mortality in two flocks of six-week old, openpenned, pre-release pheasants. The birds, supplied by a common supplier the previous
week, were penned in wooded areas during a period of very wet weather. On
investigation clinical signs of weight loss, depression and lameness were observed in
approximately three per cent of pheasants. Staphylococcus aureus was isolated from
some swollen tarsal joints (figure 3) and from other organs of birds examined post
mortem indicating a diagnosis of Staphylococcus aureus septicaemia and arthritis.
A pregnant female Sika deer (Cervus nippon) was found dead and was submitted to
Dublin. Severe necrotising and granulomatous pneumonia was diagnosed (figure 4).
Large numbers of acid-fast bacteria were observed in the lung and a diagnosis of
pulmonary tuberculosis was made. The local district veterinary office was informed
of the findings.
A Hen Harrier (Circus cyaneus) chick on the point of fledging was submitted to Sligo
by the National Parks and Wildlife Service. It had been found a short distance from
the nest and malicious poisoning was suspected. On gross examination twin puncture
wounds were discovered in the breast, and extensive bruising and internal
haemorrhage had occurred. The findings showed clear evidence of predation by a dog
or fox.
References:
Andrews E.D. (1965) Cobalt poisoning in sheep.
New Zealand Veterinary Journal. 13. 101.
CAPTIONS FOR PHOTOS
Figure 1
“ Necrotic lesions in the liver of a calf with systemic mycosis– photo Donal Toolan”
Figure2
“Haematoma in a bovine penis- photo Donal Toolan”
Figure 3
“Arthritis in the tarsal joint of a pheasant compared with a non-arthritic one- photo
William Byrne”
Figure 4
“Pulmonary tuberculosis in a female Sika deer- photo Ann Sharpe”