Veterinary Services

Nutritional and metabolic disorders

A herd of 137 spring-calving suckler cows in the Lothians with a history of vitamin E deficiency experienced three fatalities in young calves despite all newborn calves receiving a routine injection of vitamin E. The two-week-old Simmental cross calf submitted for necropsy was in good condition. Histopathology of skeletal muscle, tongue and diaphragm revealed lesions consistent with acute degenerative myopathy. Liver vitamin E concentration was 3.94 m g/kg fresh tissue. This concentration, although below the reference range for older cattle of ³ 5.0 m g/kg, would usually be considered unremarkable in a calf of this age. Nevertheless it the SAC considered that a higher concentration would have been present had the calf received the intended prophylactic injection, and concluded that some individuals may have been missed.

Generalised and systemic conditions

A nine-month-old Friesian heifer from Dumfries and Galloway was found dead with changes typical of blackleg. The left hind leg was massively swollen proximal to the hock and subcutaneous emphysema was evident (figure 1 - see top right-hand side). The underlying muscles were dry and almost black in colour. They contained numerous small gas bubbles. The fluorescent antibody test (FAT) was strongly positive for Clostridium chauveoi.

Three, ten-day-old Limousin cross calves were submitted to Dumfries from a farm experiencing severe problems with neonatal diarrhoea and septicaemia. There was a poor response to treatment and a high mortality rate. The calves were born inside, treated prophylactically for cryptosporidiosis for four days after birth and then turned out. All three calves showed a profuse scour and two showed meningitis. One of these also had a fibrinous pericarditis, pleurisy and peritonitis. The third had a severe pyelonephritis. E coli was isolated in septicaemic distribution in each case. Antibiotic sensitivity testing of isolates from all three calves revealed that the E coli from two calves was multi-resistant. Serotyping and toxin typing failed to identify any specific virulence factors. An isolate from the kidney of the third case typed as O9: K’RVC1798’, a strain which has been associated with scour and septicaemia in calves. This calf showed different pathology from the other two calves. Biochemistry confirmed hypogammaglobulinaemia and this predisposed to colisepticaemia. The calving box was the likely source of the organisms in this outbreak. A combination of calving outside and changing antibiotic treatment to florfenicol prevented further cases occurring.

Salmonella Dublin infection was diagnosed in calves from two dairy herds and a beef herd by the Ayr centre. Calves aged two weeks and four weeks were submitted from one farm, and lesions observed at postmortem examination included pneumonia, pleurisy, peritonitis and haemorrhagic enteritis.

Septicaemia and septic meningitis due to infection with Listeria monocytogenes were confirmed in a seven-day-old Charolais calf that was found dead after a short period of malaise.

Toxic conditions

Two Limousin heifers were submitted for postmortem to Dumfries. Three animals had died in the field where they had been outwintered and others were recumbent and vomiting. Leaves found in the rumen were identified as Pieris japonica. The source of these was garden waste that had been placed in the field. Pieris contains a glycoside andromedotoxin that results in death due to respiratory failure.

Lead poisoning was diagnosed when two calves were found dead in one group of cows and calves over a three-day period. Cows and calves in an adjacent field remained unaffected. The field was inspected after the second death and the remains of a car battery were found. The level of lead in the kidney was 36.5ppm (reference limit: <20ppm). This incident was reported to the Food Standards Agency.

Parasitic diseases

Coccidiosis caused scour in calves aged four to ten weeks at grass on five farms in Orkney and Caithness. Sudden onset black scour with dehydration and depression was the usual history. The oocyst counts in some calves were in excess of 500,000 per gram.

Alimentary tract disorders

The purchase of cows from dispersal sales in areas south of Caithness and Sutherland is believed to be responsible for in an increase in the diagnoses of Johne’s disease by Thurso this month. Large numbers of beef cows were moved north and many succumbed to the disease within weeks of arrival on farms. Johne’s disease was diagnosed on 18 farms. Animals between two to fourteen years were affected and all showed diarrhoea and weight loss. The family history of most cases was unknown.

A three-week-old Charolais calf appeared to recover from an episode of scour but was then found dead one week later. The carcase was anaemic and the faeces were melaenic. A blood clot filled the abomasum. A seven-centimetre area of the abomasal folds was thickened and roughened. A severe necrotising abomasitis of bacterial origin was diagnosed on histopathology, but no potential pathogens were identified on bacterial culture.

Necrotising abomasitis with fungal invasion of the vasculature was confirmed, with death suspected as a result of subsequent fungal hepatitis and toxaemia by the Aberdeen centre. The affected calf was a three-week-old Belgian Blue embryo transfer calf born by caesarean section with contracted tendons. It could stand but tended to fall over backwards. As the calf was unable to suckle, it was tubed with milk twice daily since birth.

Respiratory tract conditions

An Aberdeen Angus suckler herd of 800 cattle had experienced problems with calf pneumonia, despite routine prophylactic treatment of all calves with florfenicol. One six-week-old calf was found dead. Necropsy at Edinburgh showed an extensive pneumonia mainly involving the ventral diaphragmatic lobes, with pus in the bronchioles. There was also evidence of diarrhoea, with patchy congestion of the intestine and watery content in the colon. Bacteriological culture yielded a pure growth of Mannheimia haemolytica. Salmonella Dublin was isolated from the intestinal contents. A second calf from the same group presenting with pneumonia and diarrhoea was treated with antibiotics for two weeks without response. Bacteriological cultures from this calf were unrewarding, presumably due to the treatment, however histopathology reported chronic inflammatory changes in the small intestinal mucosa, kidney and liver consistent with a chronic active inflammatory process such as systemic salmonellosis.

Nervous system disorders

A three-week-old beef suckler calf from a Fife farm was submitted for postmortem examination having died after a four-day period of illness. The calf had displayed a high frequency of tongue protrusion prior to death. There had been no response to antibiotic treatment. External examination revealed petechiae on the underside of the tongue. Gross examination of the brain revealed an inflamed and soft area on the right hemisphere. This was associated with a large (2.5x1.5cm) abscess in the right temporal cortex extending to the meninges. No significant bacterial organisms were isolated from the lesion. Histopathology showed that the abscess was characterised by the presence of neutrophils and non-septate, non-branching hyphae with occasional bulbous shapes consistent with a fungal cause. A diagnosis of a brain abscess of unknown fungal aetiology was made on the basis of clinical symptoms and histopathological findings.

Mammary diseases

A second milk sample was collected from a cow with chronic mastitis that was unresponsive to treatment. The initial and the follow up samples were sterile on routine culture. A pure growth of Mycoplasma bovis was isolated from the second sample. The herd had not reported an increase in bulk milk somatic cell count or clinical mastitis incidence. Follow up milk sampling of high somatic cell count cows and clinical mastitis cases suggest that this is an isolated case. Milking practices and parlour hygiene are good and there is no history of pneumonia or arthritis reported in the herd.