Veterinary Services

A stillborn calf from a farm in Perthshire was submitted displaying severely stunted long bone growth. Two other calves showing limb deformities had been born on the same farm in the previous 36 hours. Necropsy revealed minimal diaphyseal development affecting all the limb bones, accompanied by epiphyseal enlargement. The joint capsules were intact. The head appeared swollen and the bones within the base of the skull were deformed. The calf was seronegative for bovine virus diarrhoea (BVD), Leptospira hardjo and Neospora caninum, and no BVD virus was isolated from body tissues. Histopathology of the brain showed a mild deformity of the medulla oblongata due to the bone deformities noted at necropsy. Bone histopathology revealed that the growth plates in the long bones were diffusely irregular and disorganised, with some lengths of growth plate missing completely. These findings were consistent with congenital chondrodystrophy of calves, usually associated with feeding of unsupplemented silage to cows during pregnancy.

Generalised and systemic conditions

Cases of neonatal septicaemia in suckled calves were reported across Scotland, however the number of submitted cases was reduced, presumably due to the warm, dry weather conditions. Typical cases are reported below:

The carcase of a five-day-old Aberdeen Angus calf was submitted from a farm in Angus. It was one of three calves that were born normally but were lethargic and listless. The calves made no attempts to rise or to suckle. Postmortem examination revealed evidence of faecal staining at the anus and tailhead and a thickened navel. Internally, the omasal and abomasal walls were thickened and oedematous with the luminal surfaces being congested and hyperaemic. The navel was oedematous. Examination of the joints revealed thick, yellow joint fluid. After bacterial culture, E. coli was isolated from all organs plus navel tissue and joint swabs. Clostridium perfringens was isolated from the abomasal wall. In addition Clostridium perfringens alpha toxin was demonstrated in gut contents. Histopathology identified a suppurative broncho-pneumonia, suppurative enteritis and suppurative abomasitis. A diagnosis of navel ill involving E. coli with secondary bacteraemic spread was made. The SAC also postulated that the detection of clostridial alpha toxin suggested a calf enterotoxaemia due to Clostridium perfringens Type B or C.

On one farm in the North of Scotland navel ill affected 20 out of 60 calves. Arcanobacterium pyogenes was isolated from navels as well as from the bottle containing iodine being use to treat the navels at birth.

A twelve-day-old Aberdeen Angus bull died after becoming cold and recumbent. Postmortem at the Dumfries centre identified that the navel was infected and there was bilateral hypopyon. There were increased amounts of ascitic, pericardial and cerebrospinal fluid and the brain looked pale. No significant organisms were cultured probably due to recent antibiotic treatment. Meningitis was confirmed on histopathology. The zinc sulphate turbidity (ZST) test in this case was 3 (reference range >14). The cow had a very large udder that made it difficult for the calf to suck.

A 12-year-old dairy cow lost condition over a three to four week period, with a sudden onset of watery diarrhoea immediately before death. Postmortem examination at the Ayr centre revealed diffuse pallor and enlargement of both kidneys, and a pale, enlarged liver with fibrotic bile ducts. Deposits of amorphous eosinophilic material were demonstrated on histopathology of the kidneys and liver. A congo red stain indicated that the amorphous material was amyloid, confirming the diagnosis of renal and hepatic amyloidosis.

Alimentary tract disorders

A clostridial abomasitis was suspected following the sudden death of a one-month-old calf in Aberdeenshire. Examination revealed abomasal ulceration, oedema and emphysema, and Clostridium perfringens was isolated on culture. Histopathological examination confirmed the presence of an acute abomasitis. The farm reported one other sudden death in the calf group.

A large suckler herd in Aberdeenshire submitted a 23-month-old heifer for postmortem examination following a history of acute onset scour and death within 48 hours. The unit reported two similarly affected animals in a batch of 40 homebred cattle. Bulls were purchased annually and the occasional calf was bought-in to set-on, with no screening at purchase. The BVD status was unknown. Postmortem examination revealed severe oral, oesophageal and small intestinal ulceration. Type 1 BVD virus was detected in pooled tissues by RT-PCR. Subsequent examination of the herd records confirmed that all three affected animals were born within a short time period in 2005. Screening of all replacement heifers in the same cohort of youngstock was recommended as the first stage in a programme to control BVD on the farm.

E coli K99 was the cause of severe sudden onset enteritis in a small group of two to four day old calves in a large beef unit in Northern Scotland. The disease was previously unrecognised on the unit but a replacement dairy calf had recently been bought in. This condition is very rarely seen in the area presumably due to effective vaccination policies.

Respiratory Tract disorders

Twelve from a group of fifty dairy heifers from a large dairy herd in Dumfries and Galloway suffered a serious loss of body condition. The animals had been wintered away from home and had not been noted to be ill. They returned home for calving in poor condition and after calving had no milk and continued to be ill thriven. One animal was submitted alive and euthanased. Severe, well-demarcated, antero-ventral lung consolidation was present with small abscesses, interlobular oedema and a fibrinous pleurisy. Mannheimia haemolytica was isolated. The chronic changes seen probably caused the original loss of condition. There was a history of respiratory disease problems in young calves on the unit. The SAC suspected that early, significant lung damage as young calves may have pre-disposed heifers to the problem presented.

Infectious bovine rhinotracheitis (IBR) continued to cause problems in all ages of cattle in Northern Scotland with outbreaks diagnosed on seven farms affecting cattle aged four weeks to three years. In some cases the presenting signs were scour, pyrexia, pneumonia, swollen heads, crusty noses and eyes and cyanosis. In only one case were the symptoms of the more commonly recognised disease type with runny eyes, excess salivation and dyspnoea. The diagnosis in all cases was made on fluorescent antibody testing (FAT) examination of tissue usually trachea, or clear eye discharge.

Reproductive tract disorders

A dairy farm in Dumfries and Galloway submitted five foetuses during an abortion storm. The majority of abortions were occurring at four to six months gestation and over 10 abortions had occurred in a four week period. Lesions consistent with a diagnosis of Neospora caninum infection were found on neuro-histopathology in four foetuses. The herd had reported an abortion rate in excess of two percent over the last two years although no diagnostic investigations had been carried out. The nature of the abortion storm suggested horizontal rather than vertical transmission, A young dog was recently introduced to the farm and it was considered a possible source of infection.

Nervous system disorders

A farm in Fife reported deaths in three calves that were found prior to death in lateral recumbency with the head pushed back. The respiratory rate was increased and facial muscle fasciculations were noted. Necropsy of one calf showed that the lungs were mildly congested and there were ecchymotic haemorrhages on the surface of the heart muscle. There was a moderate amount of straw-coloured fluid within the abdomen. The kidneys were moderately oedematous at the hilus and the bladder was markedly distended. Bacterial cultures failed to isolate any significant organisms however histopathology was more rewarding. There was evidence of acute brain swelling with marked serum leakage in cerebral and cerebellar meninges, thalamus, midbrain and cerebellar white matter. In the cerebral cortex there was acute focal malacia in the cerebellar white matter and midbrain. These findings were consistent with a diagnosis of focal symmetrical encephalomalacia caused by the epsilon toxin of Clostridium perfringens type D. Focal symmetrical encephalomalacia is an unusual finding in calves but has been previously documented by the SAC.

A four-year–old Ayrshire cow was euthanased nine days after suddenly becoming blind. The cow had a normal gait and no other nervous signs but was anorexic. It had calved six months previously and had been milking and eating normally. Blood lead levels were within normal limits. A second cow was euthanased due to loss of sight one month before. This animal had also become aggressive and difficult to handle. At postmortem at Dumfries no gross lesions were found in the eyes, optic nerves or at the optic chiasm. Histopathology revealed severe and extensive lesions of cerebrocortical necrosis. Adult animals with this condition survive longer than calves. The aetiology could not be explained. All cattle received a total mixed ration, which was unchanged and the cow was treated with vitamin B1 with no clinical response.