Current Findings in the Regional Veterinary Laboratories
November 2005
Cattle
The RVLs examined 279 bovine foetuses during the month. The pie-chart (figure 1) illustrates the
isolation rates of the pathogens identified. Salmonella dublin was the most common
abortefacient isolated. Dam serology, also plays a major role in the diagnosis of abortion. Of
approximately 765 blood samples submitted for Salmonella dublin serology, 152 (19.9 per cent)
were considered to have significant antibody titres. 522 blood samples were submitted for Neospora
caninum serology, and 114 (21.8 per cent) of these were considered to have significant titres.
Kilkenny examined a seven-day old calf, the third one to die in the herd following an acute scour.
Septicaemia was diagnosed and Escherichia coli was isolated from the liver, lung and intestines.
A zinc sulphate turbidity test reading of three units (normal level >20 units) confirmed that the calf
was agammaglobulinaemic. A light cryptosporidial infection was also detected.
Pneumonia in recently purchased weanlings was diagnosed by all RVLs. Kilkenny examined a fivemonth weanling with a history of pneumonia. Consolidation of the lung and extensive emphysema
was seen on gross post-mortem examination, and a fluorescent antibody test (FAT) was positive for
respiratory syncithial virus (RSV). A small number of worms were seen in the airways. Athlone
diagnosed infectious bovine rhinotracheitis (IBR) in an 18-month old bullock submitted from a
190-animal slatted unit. A severe, necrotic, tracheitis/bronchitis was evident at post-mortem
examination, along with severe Pasteurella-type antero-ventrally distributed pneumonia. There had
been five deaths, with up to 25 more animals showing severe clinical signs. Following the
diagnosis, a full-herd vaccination programme was initiated.
Dublin examined a Charolais weanling euthanased after it had shown proprioceptive deficits in the
left fore and hind limbs for approximately three weeks. The onset of clinical signs had appeared
to follow the administration of an intra-muscular injection of a long-acting antibiotic. Postmortem examination revealed an area of fibrosis in the neck muscles close to the transverse
processes of the cervical spine. The lesion extended in to the joint between the fifth and sixth
cervical vertebrae, which when opened revealed loss of articular cartilage, inflammation of the
synovial membrane and deposition of fibrin within the joint space. The spinal cord also appeared to
be involved, thus accounting for the clinical signs described. Limerick examined an eight-month old
weanling that died after being injected with oxytetracyline. Within a few minutes of being injected
the animal became dyspnoeic, ataxic and began frothing from the mouth. It died within minutes.
Another animal displayed milder symptoms and recovered. Lesions of tracheal congestion,
petechiation, pulmonary congestion and emphysema were noted on gross post-mortem examination.
The most notable findings on histopathology were pronounced pulmonary oedema and eosinophilic
infiltration of the interlobular septae. A diagnosis of acute anaphylactic shock was made.
Cork diagnosed bovine herpes mammillitis (BHM) in a dairy herd. The disease was recorded
only in the first-calvers that had just joined the milking cows. Some were severely affected, with
extensive sloughing of the udder skin (figure 2), while others were more mildly affected, with
blistering and hyperaemia. BHM virus was isolated.
A brain of a cow, notified to the Department of Agriculture and Food as a BSE suspect, was
examined by Cork and was found to have a very poorly developed cerebellum. The cow was three
years old, and although she had been obviously compromised in gait and balance, had successfully
bred.
Sheep
Dublin examined two aborted lambs and one placenta from a flock, which had experienced a latepregnancy abortion rate in excess of 5 per cent. No signs of illness were reported in the aborting
ewes. A marked placentitis was noted both on gross examination and on histopathology.
Preliminary testing of the placenta using the Clearview Chlamydia test was positive, as was a
modified Ziehl-Nielsen smear made from a cotyledon. As neither test is totally specific for
Chlamydiophila abortus, a presumptive diagnosis of Enzootic abortion of ewes (EAE) was made.
Serum samples were requested from a number of ewes (aborted and non-aborted) to confirm the
presence of antibodies to Chlamydiophila abortus.
Two lambs with a history of pneumonia were submitted to Dublin. Lesions found included cranioventral consolidation of the lung parenchyma, interlobular oedema and fibrinous pleural adhesions.
Pasteurella multocida was isolated from the lung of one lamb and Mannheima haemolytica was
isolated from the second.
Pigs
Athlone reported post-weaning diarrhoea and enteritis in pigs, due to Escherichia coli infection.
A lung tissue sample from an animal in the same herd showed histopathological lesions consistent
with a diagnosis of enzootic pneumonia (Mycoplasma hyopneumoniae).
Cork necropsied a 60-kilogram pig that had the characteristic lesions of right-sided heart failure. A
vegetative endocarditis was found, which involved the right ventrical valves and the myocardium.
The yellowish white mass was approximately 2cm in diameter and consisted of fibrin and necrotic
material. Streptococcus suis type II was isolated from the mass.
Poultry
Limerick was involved in an investigation of a disease outbreak in a small, free-range unit with
thirty turkeys and approximately fifty ducks, geese and fancy fowl. The turkeys had been sick for
up to three weeks, with signs of weight loss, coughing, sneezeing, decreased appetite, increased
thirst, depression and huddling. Many of the turkeys had severely swollen sinuses (figure 3). The
other birds were only mildly affected. Treatment with tylosin and chlortetracycline appeared to have
little effect. The mortality rate was low. Based on the history and clinical signs the flock was
restricted and blood, cloacal and tracheal swabs were taken and submitted for avian influenza
testing. All tests were negative for the virus. A diagnosis of Mycoplasma gallisepticum infection
was made following positive serum ELISA test results. The origin of the infection was not traced,
but the flock owner decided to cull the flock to try to eliminate the infection from the premises.
Other Species
Athlone diagnosed acute diffuse peritonitis in an Irish Draught foal that had shown signs of
severe colic a few days after purchase and transport. Post-mortem examination showed the cause to
be intestinal impaction, probably due to paralytic ileus. Limerick reported that volvulus of the small
intestine had caused the death of a fifteen-year old gelding.
Kilkenny diagnosed tuberculosis in a farmed deer. The animal had extensive tuberculous pleurisy,
with lesions in the lung substance and associated lymph nodes. Gross lesions were also seen in the
spleen and liver, as well as in the hepatic, prescapular, submandibular and retropharyngeal lymph
nodes (figure 4)
Syngamus trachea infection of pheasants was diagnosed by Dublin. An aggregate of several red
worms, with a smaller (male) worm attached to each of the larger (female) ones, forming a Y shape,
was found in the trachea of one emaciated carcass.
CAPTIONS FOR PHOTOS
Figure 1 “Microbiological analysis of bovine foetal material submitted to the RVLs during
November ”
Figure 2 “Bovine Herpes Mammilitis affecting the udder of a cow– photo Cosme Sànchez-Miguel”
Figure 3 “Mycoplasma gallisepticum infection in a turkey– photo Alan Johnson”
Figure 4 “Tuberculous pleurisy in a farmed deer- photo Donal Toolan”