Veterinary Services

Nutritional and metabolic disorders

A number of cases of downer cows were investigated on six farms in the far north of Scotland and in most phosphate and magnesium deficiency were diagnosed on the basis of blood sampling. It appears as usual that many downer cow cases in this area are related to a phosphate deficiency despite supplementary mineral feeding.

Generalised and systemic conditions

The number of disease presentations in neonatal calves was high this month. Typical cases were diagnosed by the Thurso centre where colisepticaemia was found to be the cause of death in four calves from three farms. In all cases there was evidence of poor colostrum intake and in two of navel ill. It was suspected that some cows or heifers in a small unit were sucking other cows near to point of calving and removing the colostrum prior to calves sucking. The calves were lively at birth but developed pyrexia and septicaemia at five to eight days of age.

Systemic mycosis secondary to ruminal ulceration was diagnosed by the Edinburgh Centre following post mortem examination of an 18-day-old, Limousin-cross heifer. The calf was submitted live but recumbent and in opisthotonus having initially shown clinical signs of an abnormal gait, weakness, nystagmus and a tendency to lie down with her head to the left.

At necropsy the carcass was dehydrated with poor fat reserves. There was extensive erosion of the rumen and reticulum with associated plaque formation. Two abscesses were present in the liver and there was an apparent increase in intracranial pressure noted on removal of the head. Sectioning of the fixed brain and neuropathology revealed a distinct mass composed of multiple large abscesses containing non-septate, non-branching fungal hyphae. The erosion of the rumen and reticulum was confirmed and numerous fungal hyphae and bacteria were seen to be invading the lesions and hyphae were present in thrombosed blood vessels.

Two scouring Simmental-cross calves were submitted for post mortem examination at the Perth Centre. Salmonella had previously been isolated from the sheep flock and sheep had been introduced to the cow shed. Both calves had extensive peritonitis and pasty scour and one had severe pleuritis, pericarditis and omphalitis. Salmonella Typhimurium (untypable) was isolated from both calves – the isolate presumed to be the same as from the sheep.

Alimentary tract disorders

A 17-day-old dairy heifer calf was submitted to the Edinburgh Centre from a closed herd experiencing ill-thrift, pyrexia, diarrhoea and upper respiratory tract disease starting at about seven days of age. Two calves had died at about 14 days of age. The calf submitted had shown pyrexia, diarrhoea and terminal neurological signs. At necropsy the calf was in poor bodily condition, dehydrated and gut content was scant and fluid. Histopathological examination revealed degeneration of the abomasal mucosa and of the small intestinal crypt epithelium. The crypts contained numerous large bacilli, presumably Bacillus licheniformis which had been isolated from gut contents. Acute myofibre degeneration was present in the tongue and diaphragm, hepatocytes were disorganised, the spleen depleted and the lung congested and oedematous. Acute systemic disease, e.g. toxaemia or viraemia, was suspected rather than a nutritional myopathy. However, vitamin E and selenium estimations were carried out on liver samples for completeness and adequate levels were detected. Examination of the brain revealed mild, predominantly non-suppurative meningitis and semi-suppurative encephalitis with haemorrhage consistent with an infectious process. Virus isolation was carried out principally to look for bovine herpes virus type 1 but bovine virus diarrhoea virus (BVDV) was isolated. Given the evidence of acute systemic disease acute BVDV infection was suspected but this would not explain the subacute neurological lesions. BVDV infection may explain the signs and deaths in the other calves and investigation of the source in this reportedly closed herd was advised.

A four-week-old Simmental-cross calf from Perthshire was submitted for post mortem examination, the second bloated calf to die. Post mortem examination revealed gas filled intestines with no evidence of milk ingesta and only a small quantity of coarse fibre in the rumen. A large abomasal ulcer was present from which Clostridium perfringens was isolated.

A four-week-old bucket-fed dairy calf was submitted for post mortem examination at the Perth centre. There was no evidence of milk ingesta and the small intestine was acutely inflamed. 1,800 coccidial oocysts per gram faeces were recorded. Histopathology confirmed coccidiosis as the suspected cause of the inflammation.

Diseases of the Respiratory System

Post mortem examination of a four-month-old, single suckled, Charolais heifer from the Borders, one of three calves seen to be unwell and treated with antibiotics, revealed viral type pneumonia and infection with Mycoplasma dispar. The other two calves appeared to have recovered. Gross and microscopic findings were typical of respiratory syncytial virus (RSV) pneumonia but fluorescent antibody tests (FAT) proved negative.

Gross and microscopic findings typical of RSV and secondary bacterial pneumonia were found on examination of the pluck from a four-month-old, Charolais bull calf. However, FAT, immunocytochemistry and virus isolation all proved negative for RSV, but Pasteurella multocida was isolated.

Diseases of the Reproductive System

A large number of foeti were examined typical of the time of year with Bacillus licheniformis being the most commonly diagnosed cause of abortion. Two specific cases examined at the Edinburgh Centre are described below.

Abortion due to Leptospira hardjo was diagnosed in a male Simmental foetus from a heifer due to calve in June. However, the foetus was considered to be of at least seven months’ gestation, weighing 9.27kg and with a crown to rump length of 62cm. Gross examination revealed both inhalation and ingestion of amniotic fluid but no other gross abnormalities. No placenta was received. Foetal serology indicated a positive titre of 1/400 to L. hardjo. Other serology and cultures proved negative.

Mycotic abortion, suspected to be due to Aspergillus fumigatus, was detected on examination of a premature, Charolais-cross foetus, weighing 16.7kg, with a crown to rump length of 73cm. Gross examination revealed petechial haemorrhages in the lungs and pleura and inhalation of amniotic fluid consistent with foetal hypoxia/distress. No placenta was received. Fungal hyphae were seen in the stomach content which yielded A. fumigatus. No other potential pathogens were identified.

Diseases of the urinary system

Severe renal insufficiency was diagnosed in an eight-month-old, Shorthorn-cross, neutered male stirk from the Borders. The history indicated vague malaise and constant dribbling of urine. Blood biochemistry revealed marked elevation of blood urea (36.4mmol/l, reference range 2.0-6.6), creatinine (790mmol/l, reference range 44-165) and phosphate (2.5mmol/l, reference range 1.7-2.2).

Nervous system disorders

Ataxia, blindness, recumbency and bloody scour were noted in five recently calved dairy heifers in Perthshire. Two heifers were euthanased on animal welfare grounds, one of which was submitted for post mortem examination.

The rumen of the 400 kg cow contained a coarse fibre ingesta, a sparse quantity of cereal grains and an excess of water. The abomasum had congestion of the rugae with small intestinal inflammation, congestion and loops of blood filled small intestine. Mesenteric lymph nodes were enlarged. The ileocaecal junction had sparse circular ulcers approx. 1-2 mm in diameter. At the level of the mid - colon numerous similar ulcers were evident. The large intestinal lumen was full of watery blood.

Smears and cultures of the ulcerative lesions revealed no potential pathogens. Serology proved positive for malignant catarrhal fever (MCF).

Histopathology confirmed an "ulcerative typhlocolitis", but no changes to suggest a toxic insult, renal or hepatic failure or MCF. Neuropathological examination of the brain revealed severe, widespread polioencephalomalacia of laminar pattern with marked pericapillary oedema, pericyte proliferation and necrosis of neurones affecting chiefly the middle to deep laminae of the cerebral cortex, with necrosis of all laminae in certain gyri. These changes were considered suggestive of either cerebrocortical necrosis (CCN) or certain cases of lead poisoning.

Kidney lead levels were not raised and blood lead levels were not raised in a further two affected heifers. There were no other significant results despite a wide range of tests being conducted.

Skin disorders

Histopathological examination confirmed actinobacillosis in a yearling Charolais bullock, with an ulcerated hard palate and a large mass protruding from the right nostril.