Current Findings in the Regional Veterinary Laboratories
May 2004
Cattle
Athlone reported low calcium, magnesium, inorganic phosphorus and copper in blood samples
taken randomly from cows in a purebred Limousin suckler herd. There was a recent history of illthrift, infertility and retained placentas. The animals had been receiving a mineral additive in the diet
up to two years ago when the practice was discontinued. Clearly highly bred stock on marginally
fertile land will need mineral supplementation.
Kilkenny diagnosed a number of cases of neonatal septicaemia. These cases usually had very low
Zinc Sulphate Turbidity Test (ZSTT) levels. In these times of reduced help on farms, labour
demanding tasks such as feeding assistance to newborn calves is often not undertaken. Large calves
born to cows with pendulous udders often have great difficulty in obtaining adequate colostrum intake
without assistance. Athlone reported high mortality in dairy calves under one week old due to K99
E.coli enterotoxaemia. Sligo also reported the isolation of E.Coli K99 from a faecal sample from a
calf presenting with diarrhoea. Kilkenny continued to diagnose Rotavirus, Cryptosporidia and
Coronavirus as causes of neonatal enteritis in calves during the month of May.
Salmonella dublin was isolated by Kilkenny from a number of two to twenty-one days old claves
submitted for PME. It was associated with scour, hepatitis, pneumonia and septicaemia in different
cases. Histological examination of one of the cases identified multifocal areas of necrosis and
inflammation of the liver, consistent with salmonellosis. Athlone isolated Salmonella dublin from a
nine-week-old calf which came from a herd in which calves showed a lack of thrive from three weeks
of age with hair loss on the legs. There were a number of losses and the survivors were in poor
condition. Oral and parenteral antibiotics and oral tonics were used for treatment. A one-month-old
calf with a history of sudden death was submitted to Limerick RVL for PM examination. Meningitis
was seen on gross examination. Haemophilus somnus was isolated from the brain. A four-day-old calf
that died suddenly was submitted to Sligo RVL for post mortem examination. The owner said it "was
running around the evening before." Gross examination of the carcass, which had rapidly autolysed,
revealed an intense sweet smell that is associated with Blackleg. Examination revealed fine fibrin
strands on the heart. Additionally, the carcass musculature was diffusely emphysematous and dry
looking but pale rather than black. Clostridium chauvoei was demonstrated in muscle impression
smears from the heart.
Athlone reported mesenteric torsion in two two-month-old calves from different suckler herds. The
history indicated that in both herds the calves had ad lib access to creep feed. A two-month-old calf
submitted to Cork died following strangulation of the small intestine around the hepatic ligament. A
three month-old calf received by Cork was from a herd with a history of pneumonia. This calf had
been treated twice for pneumonia. At post-mortem the main lesion was a large abscess occupying the
auricle, the tricuspid valve and upper half of the right ventricle (see figure 1). The heart was markedly
enlarged. Staphyloccus aureus was isolated from the abscess and the lung. Histopathology of the
lung showed a moderate interstitial pneumonia consistent with embolism.
One of two young, but very well grown, 150kg suckled Charolais calves presented with a history of
bleeding from the gums and sudden death and was found by Dublin to have multifocal
haemorrhages in buccal mucosa, all striated muscles, spleen, oesophagus and thymus together with
diffuse haemorrhages extending over entire serosal surface of active viscera, i.e. myocardium,
mediastinum and large areas of serosal surfaces of rumen, caecum and bowel. Focal haemorrhage in
lung including a 2cm diameter blood clot and diffuse haemorrhage in submucosa of trachea all
indicated a generalised failure of the blood coagulation mechanism. Toxic anticoagulants and the
thrombocytopenic version of BVD were considered in the differential diagnosis but none were
confirmed. A second sudden death calf in the herd had suppurative bronchopneumonia. Listerial
encephalitis was diagnosed by Dublin based on characteristic histological appearance in one two-yearold bullock. This was the third animal with a history of unilateral nervous signs on this farm.
An outbreak of bovine botulism was suspected as the cause of death of four yearling Friesian heifers
on a dairy/poultry farm. Two other animals from the group of fourteen were showing clinical signs of
flaccid paralysis. An investigation into the outbreak by Limerick RVL reached the conclusion that the
most likely source was a heap of poultry litter located in the field where the heifers were grazing. The
area had been inadequately fenced off and it was likely that the heifers had direct access to it.
Limerick RVL is encountering an alarming rise in the number of suspected bovine botulism outbreaks
in recent months. In the outbreaks that have been investigated to date, there has always been a definite
link with improper management of poultry litter and poultry carcass disposal either on that farm or on
a neighbouring farm.
Sligo reported that type II ostertagiasis caused the death of a three-year-old cow. This was the third
animal to die on the farm with an intractable scour over a one-month period. Following investigation
it seemed likely that a comprehensive programme of preventive anthelmintic use in the first two
grazing seasons might have impaired the development of immunity. Tickborne fever was diagnosed
by Cork in a repopulated dairy herd. The clinical signs were of pyrexia and milk drop. Bodies with
the typical morphology of Ehrlichia phagocythophilia were present in many of the white blood cells.
Sligo reported an outbreak of lead poisoning in adult dairy cows in a small milking herd. Three
cows died with acute onset and short course of a syndrome of nervous signs (hyperexcitability,
incoordination, impaired vision) and severe enteritis. At PME, there was acute enteritis, and foreign
bodies were found in the reticulum (styrofoam beads, plastic fragments, fine wires, soft malleable
metal fragments). A sample of renal cortex contained 50 ppm lead. Athlone reported lead poisoning in
a group of heifers that were recently put out to rented land. The first sign of the problem was sudden
death in one animal followed by two others that initially showed signs of gastro-enteric pain followed
by partial blindness and stupor. A battery was subsequently found in the field.
Sheep
Kilkenny diagnosed several cases of Pasteurellosis in young lambs. Fibrinous pleurisy, pneumonia
and pericarditis are the common findings. In many of these cases there was a concurrent infestation
with Coccidia spp., Nematodirus spp or Strongyle worms. It is essential that sheep farmers have a
good anthelmintic programme in place and that the timing of treatments are strictly adhered to. Three
eight-week-old lambs submitted to Limerick for post-mortem examination were diagnosed with
parasitic gastroenteritis. Teeth grinding and frothing at the mouth were the only clinical signs observed
by the farmer before the deaths occurred. Athlone found evidence of a very low copper status and a
heavy coccidial infestation in lambs that were not thriving from three weeks of age.
A four-month-old lamb was presented to Sligo in lateral recumbency with ‘paddling’ movements.
Gross examination of the brain revealed haemorrhages into dorsal cranium over the cerebellum. A pea
sized lesion -suspected teratoma - was evident on the dorsal aspect of the cerebellum (see figure 2).
Histopathological examination of cerebellar lesion confirmed a hamartoma.
Sligo reported a Louping-ill outbreak in a sheep flock that had multiple deaths. Ticks were present
on the carcasses and the ages of animals presented to the laboratory ranged from two months to four
years. Post mortem examination of an adult ewe presented with a history of dullness, later panting and
proceeding to isolate from the flock revealed a vegetative endocarditis of the atrioventricular valve.
Streptococcus spp. was isolated
Horses
A one-week-old foal presenting with abdominal distension was submitted to Cork. On opening the
cavity a large amount of ascitic fluid was found. Further search revealed a ruptured bladder with a
focal tear (approx. one cent coin size) and moderate fibrosis and haemorrhage bordering it indicating
that uroperitoneum was present. Also pleural effusion and moderate omphalitis were observed, from
which a swab was taken and Streptococcus spp. was isolated. It is suggested that the infection of the
umbilical artery led to inflammation and weakening of the bladder wall. Streptococcus equi subspecies
equi was isolated in Limerick RVL from a swab taken from a submaxillary abscess on a colt foal.
The history was that a number of horses were affected on the stud farm and that control of spread was
proving very difficult.
Figure 1 “Purulent material in right side of a calf heart – photo Pat Sheehan”
Figure 2 “Hamartoma on the cerebellum of a lamb – photo Sligo RVL”
Dogs
Athlone reported Angiostrongylosus vasorum in a dog that presented clinically with progressive
respiratory distress and anaemia and did not respond to treatment. Lung histopathology showed the
presence of eggs and larvae in the tissue with a diffuse chronic interstitial pneumonia and numerous
heart failure cells. This parasite is commonly found in the pulmonary arteries and right ventricle of
dogs and foxes. The eggs and larvae produced at these locations are carried to the lungs in the
circulation. They migrate through the alveoli where they cause either an acute reaction with
pneumonia and pulmonary oedema or a more chronic congestive heart failure. The disease may extend
over several months or even years. At first there are few signs except at exercise. Later on respiratory
distress becomes more evident and progressive. The signs are more marked in sporting dogs. The
temperature remains normal throughout except towards the end when it falls, the dog is anaemic and
the appetite is small. Death is due to congestive heart failure. The intermediate hosts are varieties of
slugs and snails that are eaten by the dog. Larvae are found in the faeces but since egg production is
seasonal the accuracy of diagnosis is variable except in the endemic situation.