Veterinary Services

Nutritional and metabolic disorders

Severe lung oedema was the predominant postmortem feature in a suckled calf aged three months that had been found dead, the third such death in three weeks. Hypomagnesaemia was diagnosed on the basis of a rib calcium to magnesium ratio of 136 (reference range is 30 to 70).

An acute degenerative myopathy consistent with vitamin E/selenium deficiency was associated with late abortions and stillbirths in an organic Galloway suckler herd. A neonatal calf submitted to Edinburgh for postmortem examination had well-inflated lungs and wear on the hooves, however it had not sucked. Although the trachea was patent, from the bifurcation of the bronchi downward the airways were full of amniotic fluid. The SAC concluded that the calf had breathed, risen to its feet, but subsequently collapsed and inhaled stomach contents. Nutritional myopathy was diagnosed following histopathological examination of myocardium and skeletal muscle.

Generalised and Systemic conditions

Babesiosis was suspected in a three-year-old cow from Argyll that was anaemic, became recumbent and subsequently died. An on-farm postmortem examination revealed a jaundiced, anaemic carcase, dark-coloured urine in the bladder and bronzed liver. Tissue copper values were within the reference range, but haematology demonstrated a hypochromic, macrocytic anaemia with Babesia-like organisms in some erythrocytes. The animal grazed pasture known to carry ticks.

Parasitic diseases

Coccidiosis was a common diagnosis reported by centres across Scotland, particularly in spring born suckler calves at a susceptible age. In a typical case, a five-week-old Charolais cross calf was grazing in a field with a history of coccidial problems. The calf presented weak, ataxic and scouring, and died three days later despite treatment. Postmortem examination at Edinburgh revealed typhlocolitis with a coccidial oocyst count of 1,900 per gram of intestinal contents. Coccidial-type damage in the large intestinal tissues was noted on histopathology, although coccidial forms were not seen, presumably because of treatment.

Lungworm larvae were detected in faeces from a group of yearling cattle in Caithness, the earliest in the year the parasite has been detected by laboratory methods in the area. The calves were coughing and some had been treated for bacterial pneumonia without success.

Acute liver fluke infestation confirmed at necropsy was the cause of sudden death in two calves aged eight weeks and 14 weeks on two farms in northern Scotland. Both herd owners knew of liver fluke problems on the farms but had never had cases of sudden death in cattle. Unlike sheep, acute fasciolosis is less commonly described in cattle, particularly in calves so young. One risk factor that was identified was moving cattle onto fields that had recently been cleared for silage, prior to grass re-growth. The cattle were therefore grazing the wetter areas at field margins where machinery could not travel and grass was plentiful. These areas would be particularly suited to snail activity with high levels of challenge by metacercariae. The owners of both farms are considering methods to fence off the worst affected areas of fields. The SAC notes that grazing recently cleared silage fields is a common practice, particularly in suckler herds and the risks highlighted by these cases need to brought to the attention of farmers.

Alimentary tract disorders

An Aberdeen Angus bullock from Aberdeenshire was euthanased after a clinical history of depression, a crusting nose and a single ragged mouth ulcer. Significant findings at postmortem examination included an orange discoloration to the liver, abomasal mucosal erosions and haemorrhagic small and large intestinal contents. Numerous discrete raised flat nodules varying in size from a few millimetres to a few centimetres in diameter in the terminal ileum extending into the colon were also noted (figure 1 - see top right-hand side). Histopathology confirmed the presence of an acute hepatopathy and some of the features of the intestinal lesions were suggestive of Bovine Virus Diarrhoea (BVD). However the herd is on a BVD vaccination program, a recent screen of the youngstock showed no evidence of exposure to BVD and BVD virus was not detected in blood or tissue samples from the carcase. Serological examination for malignant catarrhal fever was negative, and no significant organisms were recovered on systemic cultures. Tissue analysis provided no evidence of copper or lead toxicity. No specific diagnosis was reached in this case.

A six-day-old Ayrshire bull calf that died after a short history of bloat and scour was examined at Dumfries. A ten-centimetre diameter area of ulceration in the abomasum (figure 2 - see top right-hand side) had perforated and abomasal contents were free within the abdomen. There was no evidence of peritonitis suggesting a per-acute death. No pre-disposing factors were identified.

Respiratory tract diseases

Malignant Catarrhal fever (MCF) was identified in cattle from seven herds in northern Scotland on the basis of clinical examination and positive antibody titres in blood samples collected in the acute stages of disease. Thurso typically diagnoses only one or two cases of MCF each year. The reason for the increase in cases is unclear. Some of the animals never had direct contact with sheep or wild deer. The presenting signs were commonly pyrexia, facial swelling with nasal and conjunctival discharge. Most had diarrhoea prior to the head lesions being seen. All cases were about one year of age and all died or were humanely destroyed.

Pasteurellosis in suckled calves at grass was widely reported. A typical case was an eight-week-old calf submitted from a Perthshire farm. The calf was one of six, which had died in the previous month after showing symptoms of pneumonia. Necropsy revealed a severe subacute fibrinous pleurisy and pneumonia, with severe antero-ventral consolidation. Culture of the affected lung tissues resulted in growths of Pasteurella multocida and Arcanobacterium pyogenes. Histopathology revealed a severe exudative bronchopneumonia with oedema, fibrin exudation and haemorrhage. The respiratory bronchioles contained 'streaming' neutrophils consistent with pasteurellosis and there was evidence of previous or chronic bronchiolitis.

A Perthshire beef suckler unit submitted a two-month-old calf that died following a short illness. The main finding at necropsy was bilateral purulent and necrotic ulceration of the vocal cords that tracked down to the underlying cartilage and considerably narrowed the lumen of the larynx. More ulcers were present in the oesophagus and there were many pale areas in the cortices of both kidneys. Culture of laryngeal tissues yielded a mixed bacterial growth including Arcanobacterium pyogenes. On histopathological examination the kidney showed a subacute to chronic tubulo-interstitial nephritis with terminal nephrotic changes. These changes were consistent with a chronic, bacterial-type nephritis and the terminal changes were associated with dehydration.

Reproductive tract conditions

Ayr diagnosed Campylobacter fetus abortion on two farms. Campylobacter fetus ssp. venerealis was isolated from foetal stomach contents and foetal liver from a farm where four cows had aborted at around six month’s gestation. Campylobacter fetus ssp. fetus was recovered from foetal stomach contents from a near-term aborted calf, from a small herd that shared a bull.

Dumfries diagnosed foetopathy due to Salmonella Dublin infection on two dairy farms. In one outbreak among the nine calvings in two weeks, there were six abortions, two stillbirths and one very poor calf that was euthanased. Most of the aborting cows were dry but those that were lactating were off colour with milk drop and retained foetal membranes.

Musculo-Skeletal conditions

Edinburgh diagnosed congenital dyschondroplasia in a spring-calving suckler herd that was housed during winter on a diet of silage and straw. Six stillbirths/neonatal deaths occurred during the first two weeks of calving. A stillborn, deformed Charolais-cross calf was submitted for postmortem examination. Two other live calves were reported to be exhibiting a similar deformity. The calf showed disproportionately short forelimbs and the forefeet turned out approximately 30 degrees. There was evidence of joint enlargement and hypertrophied epiphyses. The skull was disproportionately thick, the sutures were fused and the fontanelle was absent. Tendons were contracted and joints immobile. The length to width ratio of humerus was 2.1 (reference range 2.6 to 2.7) and consistent with a diagnosis of congenital dyschondroplasia (figure 3 - see top right-hand side). In addition there was an extremely large atrial septal defect. Cardiac defects are not generally described as part of the syndrome. Congenital dyschondroplasia is associated with feeding pit silage. Increasing the amount of straw consumed is recommended to reduce the number of new cases.

Severe skeletal malformations were also seen in three, newborn calves on an Angus farm. The third calf was delivered dead by caesarian section and submitted for postmortem examination. The abnormalities included a severe deviation of the sternum, ribs and thoracic spine to the right side. The head was narrowed and the jaw severely undershot. There was also marked twisting and deviation of the limb joints, although the long bones themselves appeared to be of normal dimensions. Histological examination of the brain showed dilated lateral ventricles and central canal. There was a paucity of myelin in the cerebrum and cerebellum and in the latter there was considerable dysplasia. Also many Purkinje cells were associated with eosinophilic "torpedoes" in the adjacent internal granular layer. In the liver there was vacuolation of hepatocytes and in the placenta non-specific oedema of mesenchyme. These changes were consistent with those of BVD but not pathognomonic. Virus isolation for BVD virus was unsuccessful and the final diagnosis was of congenital arthrogryposis of unknown aetiology.