Veterinary Services

Nutritional and Metabolic conditions

A three-week-old suckled calf from a Ross-shire herd, the second calf to die in two weeks, was submitted for postmortem. The calf had presented with respiratory distress, anaemia and a cardiac murmur. In this case the heart was grossly dilated, especially the right side. The myocardium had pale streaking and there was a pericardial effusion. The liver vitamin E level was low at 2.28umol/kg FW (reference range >5.0umol/kg FW) despite having received a vitamin E / selenium injection at birth. On histopathology there was evidence of a degenerative myopathy in the skeletal muscle consistent with a diagnosis of white muscle disease.

Another presentation of the disease in Invernesshire was on an organic dairy herd where six, 12-18-month-old heifers became recumbent, seven days after they had been turned out. The GSH-Px levels ranged from <1.0u/ml RBC to 3.8u/ml RBC (reference range >23.0u/mlRBC). The vitamin E levels ranged from 0.6-3.1umol/l (reference range 3.0-18.0umol/l). The heifers had been fed a mixed ration including minerals at the correct inclusion level however there had been a change to the winter feed with propionic acid used as a preservative.

Two of the heifers were submitted for postmortem. One was 18-months-old and it had a focus below the left hip where the muscle was very dry, pale and friable. On histopathology this was found to be an area of frank necrosis, which could have occurred due to vascular compromise following thrombosis or recumbency. In the skeletal muscle there were dramatic mixed changes. In some areas there was acute myofibre degeneration with haemorrhage and inflammation and there were also areas of extensive fibrosis with ongoing myofibre degeneration. The second case was a twelve-month-old heifer that had pale muscles and on histopathology the intercostal muscle had a marked diffuse increase in cellularity. There was diffuse myofibre degeneration and repair with scattered swollen, eosinophilic hyaline fibres, flocular fibre degeneration and foci of early mineralisation. All of these lesions were associated with a localised cellular infiltrate, either macrophages mopping up degenerate fibres or proliferating satellite cells. These were severe cases of white muscle disease.

Respiratory tract conditions

A four-week-old Charolais heifer was presented alive to the Dumfries Disease Surveillance Centre (DSC) after failing to respond to treatment for pneumonia. It was the third calf to be affected. They had all developed dyspnoea at two weeks of age and appeared initially to improve before deteriorating and dying. The calf was recumbent and mouth breathing with its head and neck extended. Little pressure was required to obstruct the larynx. Necropsy revealed a necrotic laryngitis, pneumonia and abomasal ulceration with Fusobacterium necrophorum isolated from the larynx and lungs.

A suckler herd in Ross-shire lost three spring born calves in two days due to pneumonia, despite treatment with two others were severely affected. The cattle were still housed due to the poor weather. A one-month-old calf was submitted for postmortem examination and was found to have severe pneumonia involving almost all of the lung tissuse, which was very heavy, congested, hyperaemic and oedematous. Mannheimia haemolytica was isolated in culture and on histopathology there was evidence of an acute interstitial pneumonia with widespread necrosis of alveolar walls, fibrin exudation, hyaline membrane formation and an interstitial infiltrate. There was also a focal acute suppurative pneumonia. A viral cause with secondary bacterial infection was suspected, however fluorescent antibody tests (FAT’s) for Respiratory Syncytial Virus (RSV) and Parainfluenza type 3 virus (PI3) were negative.

Reproductive tract conditions

A 10-year-old Simmental cow that died suddenly was submitted for postmortem. The 680kg cow had very pale mucus membranes and all organs were very pale. The uterus was dilated with bloody fluid and clotted blood (approximately 20 litres all together). The uterine wall was oedematous and the uterine wall layers were separated by large blood clots and oedematous tissue. An at term foetus was present in the uterus. No bacteria were seen in a Grams smear of the uterine wall and no significant organisms were isolated on aerobic or anaerobic culture. Histopathology demonstrated extensive haemorrhage and oedema of all layers within the uterine wall but no evidence of any inflammatory changes, tissue necrosis or infection. The capillaries were all significantly distended. The findings were suggestive of acute obstruction to venous return resulting in tissue haemorrhage and oedema. Possible causes include conditions such as uterine torsion, some form of obstruction arising from increased intra-abdominal pressure or a local lesion constricting or obstructing the vasculature (for example a tumour). None of these conditions were recorded grossly.

At the Dumfries DSC, five abortions occurred over a month in a group of 120 cows vaccinated for Leptospirosis. Histopathology of the livers of two foetuses revealed mineralised necrotic foci. Immunohistochemistry was positive for Bovine Herpes Virus 1 (BHV1) on the liver of one case and the liver and placenta of the other. No virus was isolated from foetal tissues and foetal fluids were seronegative for BHV1. As is commonly the case for abortions the dams were strongly seropositive for BHV1. Whole herd vaccination has been carried out, and to date no further abortions have occurred. Although BHV1 is a recognised cause of abortion it is rare to make a definitive diagnosis from foetal material and this investigation highlights the importance of histopathology as a means of confirming the diagnosis in aborted foetuses.

Musculoskeletal conditions

Eleven of 25 Charolais cross spring calves, were born deformed with varying degrees of joint laxity. The dams had been fed exclusively silage over the winter period. One of these calves was submitted for postmortem. The 34 kg calf had apical lung expansion only. The limbs appeared very short with excess movement in nearly all joints. The ratio of the long bone length to distal extremity width was 2.0 (normal - 2.6-2.7) indicative of congenital chondrodystrophy. The farmer was given advice about feeding to prevent the reoccurrence of this condition.

A septic polyarthritis was confirmed at the Aberdeen centre in a 10-day-old Simmental bull calf with a history of apparent blindness and a tendency to fall over if startled with onset of clinical signs at two days of age. Four affected calves were reported. A neurological examination did not reveal any cranial nerve deficits but there was a septic arthritis of the limb joints and the atlanto-occiptal joint with accumulations of fibrin and purulent material. Although cultures yielded only a scant growth of E coli, cytological examination of joint fluid revealed very large numbers of white blood cells, predominantly neutrophils.

Alimentary Tract Conditions

Coccidiosis was a commonly diagnosed problem in young beef suckled calves at grass across Scotland this month. An eight-week-old Aberdeen Angus calf was submitted to the Perth DSC with a history of gasping for breath prior to death. No gross pathology was evident in the respiratory tract. The small intestinal mucosa was haemorrhagic and the lumen was full of bloody contents. The oocyst count on intestinal contents was negative. However, histology indicated large numbers of coccidia within the crypt epithelium and lumen of the small intestine.