Veterinary Services

Nutritional and metabolic disorders

Degenerative myopathy due to vitamin E and selenium deficiency was diagnosed by the Edinburgh centre in a group of four-month-old, single suckled calves. One had had a fit the previous week, recovered quickly but died the next day. Two other calves collapsed after running around but recovered. Blood samples were submitted from four animals. Two showed elevated creatin kinase levels (10,470 and 2,211 iu/l, reference range <50) and reduced vitamin E (1.4 and 2.1 umol/l, reference range 3.0 to 18.0) and GSH-Px (17.2 and 13.8 U/ml red blood cells (RBC), reference range >23 U/ml RBC).

Parasitic diseases

Large numbers of coccidial oocysts were observed in faecal samples from two 12-month-old beasts with acute onset haemorrhagic enteritis and tenesmus. The group of 31 cattle was recently moved to an area where coccidiosis was previously confirmed in younger calves.

Numerous cases of chronic fascioliasis in cattle aged nine months and above in beef suckler herds were diagnosed in the far north of Scotland. Eleven herds were found with the disease (based on faecal egg counting) which was causing scour and in some cases submandibular oedema. Typically the animals had not been treated in the past twelve months and in four cases the diagnosis was the first recorded instance of fluke in the herds. The SAC noted that it was difficult to determine where the parasite will be found or not found on the basis of local knowledge and experience without surveying for the mud snail intermediate host. The disease is now diagnosed in cattle grazing low ground coastal ‘links’ pastures previously thought fluke free.

Again in the far north of Scotland parasitic gastro-enteritis was identified as the cause of scour of sudden onset in outwintered cattle on six farms based on faecal examination. Although the animals had been treated with avermectin type products in late 2006, re-infection would have taken place in 2007 due to the exceptionally warm weather.

General and systemic conditions

With the spring calving season for suckler herds underway there was the usual increase in the number of calf septicaemia cases. A seven-day-old beef Limousin cross calf was submitted from a herd in Invernesshire. It was the second out of a group of eight calves to die despite treatment with antibiotics and vitamin E. Postmortem examination showed engorgement of the blood vessels of the subcutis and congestion of the navel region. Lung lesions suggestive of inhalation pneumonia and an extensive necrotic peritonitis were present. There was a purulent synovitis and meningitis. Systemic cultures were sterile, perhaps reflecting antemortem antibiosis. However a diagnosis of blood borne spread of an acute bacterial infection was made on the basis of gross pathology and histopathology.

A ten-day-old Simmental-cross calf was submitted to the Ayr centre for postmortem examination with the history of lethargy, recumbency and abdominal pain. Substantial petechial and echymotic haemorrhages were found under the skin, in the lungs, spleen, kidney and meninges, and on the epicardium, myocardium and endocardium. The liver showed widespread subcapsular haemorrhages and multiple sunken grey foci throughout the parenchyma. A small growth of Listeria monocytogenes was recovered from the liver lesions. Histopathology revealed numerous foci of coagulative necrosis, some containing numerous bacteria, in the liver, and scattered foci of coagulative necrosis were also found in the spleen. A widespread suppurative fibrinoid meningo-encephalitis with thrombus formation was found in the brain. Cases of thrombo-embolic meningoencephalitis are usually associated with Histophilus somni infection, but in this case the isolation of Listeria monocytogenes was probably significant.

With the lambing season bringing about closer proximity of cows to sheep on some farms more cases of malignant catarrhal fever (MCF) were reported. An eighteen-month-old Limousin cross heifer from a farm in Angus exhibited ocular discharge and corneal opacity over a period of a week. For the 24 hours before it was euthanased the animal appeared to be in pain, ataxic, pyrexic and eventually recumbent. At necropsy, examinations revealed a marked bilateral cloudiness of the cornea and acute keratitis. There was extensive petechiation within the oral cavity and ulceration of the tongue, which extended down into the pharynx, larynx and oesophagus. More chronic ulceration was noted in the abomasum and echymotic haemorrhages were seen within the small intestine. A diagnosis of MCF was reached when both and herpes virus type 2 antibody and DNA were detected.

MCF was diagnosed at the Thurso Centre in a one-year-old calf; one out of 150 in a large beef herd where cattle and sheep commonly cohabited. The animal was humanely destroyed since it was unable to see or eat and drink due to the severity of the lesions. No other cattle were affected.

Alimentary tract disorders

Atresia ilei was established as the cause of the death of a calf which died at less than 24 hours of age by the Aberdeen centre. The aetiology of this condition is unknown but it has been linked to a recessive gene in Jersey cattle. A new Limousin bull had sired the calf crop. Another calf was reported to have died suddenly at one week of age but the death was not investigated. The farmer was encouraged to submit any further neonatal calf deaths for postmortem examination.

Respiratory tract diseases

A five-year-old Holstein cow was euthanased and submitted to Dumfries in an investigation into the causes of respiratory disease in adult cattle in a large dairy herd. The cow had a ten-day history of pneumonia that was unresponsive to antibiotics and was losing condition. At necropsy large numbers of adult fluke were seen in the liver and there was endocarditis of the right atrio-ventricular valve. The anterior lung lobes were over inflated with interlobular emphysema. The posterior lobes were purple but not consolidated. Certain areas appeared bright yellow on section (figure 1 see top right). Arcanobacterium pyogenes was isolated from the heart while histopathology confirmed an active chronic bacterial pneumonia. Gram positive cocci and eosinophilic club colonies were seen. Yellow material was visible in macrophages. A possible explanation of this was from haemorrhage following thrombosis from the endocarditis lesion, as haematoidin, an early breakdown product of haemoglobin, is yellow in colour. An alternative explanation was due to aspiration after drenching, however this was not reported in the history.

Reproductive tract conditions

There was a seasonal increase in abortion submissions from suckler herds. Bacterial causes of abortion predominated including Bacillus licheniforms and Listeria monocytogenes. Fodder and environmental contamination of housed and out-wintered late pregnant suckler cows being the most likely cause of these infections.

A near-term Simmental cross Limousin foetus was submitted for investigation from a suckler herd in Ross-shire. Postmortem examination showed significant lesions in the thoracic cavity. An excess of pleural fluid was found with a thick fibrin layer in the pleural space loosely covering parts of the lungs and pericardium (figure 2 see top right). Campylobacter fetus ssp. fetus was cultured from foetal stomach contents, foetal lung and liver, consistent with a diagnosis of campylobacter abortion.

Abortion due to Campylobacter fetus spp. fetus was also diagnosed in a foetus of around six-month gestation submitted from a herd in Perthshire. No significant lesions were recorded on gross examination of the carcass, but typical gram negative curved bacilli were observed in a smear of foetal stomach and Campylobacter fetus spp. fetus was isolated from the foetus and placenta.

Routine examination at the Edinburgh centre of late gestation, crossbred foetuses from two separate farms yielded a heavy, pure growth of Arcanobacterium pyogenes from the stomach content. In both cases the mothers had been vaccinated against Leptospira hardjo. Positive antibody titres to Leptospira hardjo were detected in the foetuses. Histopathology failed to reveal any changes specifically associated with Leptospira hardjo infection. The SAC VS proposed that the antibodies were of maternal origin and had crossed the placenta following damage caused by Arcanobacterium pyogenes infection.

Pasteurella multocida was grown in pure culture from the liver, lung and stomach contents of a six-month-old Holstein foetus. Histopathological changes were consistent with abortion due to a bacterial infection. Pasteurella multocida had been previously cultured from mastitis cases on this Dumfriesshire farm.

Salmonella Typhimurium phage type 104b was isolated from a faeces sample from a three-year-old Aberdeen Angus cow which aborted after a ten-day history of dullness, scour and subsequent abortion when seven months in calf.

Nervous system disorders

A three-year-old Limousin cross heifer appeared dull and lethargic on clinical examination. The cow was purchased 12 days earlier in a group of 38 animals and was the only one affected. It was pyrexic and was euthanased after becoming recumbent. An increased quantity of thick cerebrospinal fluid was noted. Arcanobacterium pyogenes was isolated from the fluid and bacterial meningitis diagnosed. The pre-disposing factors for this condition in an animal of this age were uncertain.

Encephalitis due to bovine herpes virus type 1 (BHV1) infection was diagnosed at the Edinburgh centre in a 9-month-old, Limousin-cross bull from a farm experiencing a severe Infectious bovine rhinotracheitis (IBR) outbreak. The animal had been recumbent for 48 hours with weakness of all four legs but appeared bright. Examination of a CSF sample revealed a monocytosis. The bull was euthanased as there was no response to antibiotic and steroid therapy. Necropsy revealed a severe, necrotising rhinitis consistent with IBR although fluorescent antibody tests were negative. No gross abnormalities were detected in the brain, spinal column or other systems. Histology of the brain revealed mild spongy change in the fore and mid brain and sub-acute to chronic mononuclear cell inflammation in the medulla. Specific immuno-histochemistry for bovine herpes virus-1 showed positive labelling in the medulla.