Veterinary Services

Nutritional and metabolic disorders

Fluorosis was initially suspected in a batch of Angus-cross bullocks aged 18 months. The animals had returned from their second summer at grass in poor condition, and three of the group of 16 became recumbent and died or were euthanased. Heifers in the same batch were unaffected. The incisor teeth of one of the two animals submitted to the Ayr Centre were unevenly worn, with black discolouration at the cutting surface and at the gum margin. The teeth appeared to be loosely embedded in the jaw, with haemorrhage at the tooth-gum margin (see figure 1 at top right). The enamel of the incisors of the second animal was also pitted and irregular. In addition, this animal had a bilateral keratoconjunctivitis and a subacute suppurative pneumonia from which Pasteurella multocida was isolated. Subsequent bone analysis did not support the diagnosis of fluorosis, but blood samples revealed low or marginal calcium and phosphorus status consistent with a mineral deficiency. A complicating factor was the demonstration of antibodies to malignant catarrhal fever in the affected animals, suggesting that the batch had also been exposed to this virus.

Selenium deficiency was found in three groups of growing cattle in the north of Scotland where although some animals were thriving others were not. No clinical disease problem was apparent. The GSH-PX levels were all below 10 units/ml RBC (reference range >23units/ml RBC). Selenium therapy by injection seemed to improve appetite and demeanour within two weeks in one group of 60 beef crosses aged 15 to 18 months. It was postulated that at housing the animals suffer from selenium deficiency as a result of grazing selenium deficient pastures. Unless they are fed a selenium supplement their selenium status remains deficient because the home produced fodder is also deficient in selenium.

Parasitic conditions

Liver fluke eggs were found in large numbers in faeces from two outwintered groups of cattle in the north of Scotland that were failing to thrive despite treatment with an injectible flukicide in late 2006. The SAC suspected that they were still picking up viable metacercaria at this stage and by February 2007 these had developed and started to produce eggs.

Generalised and systemic conditions

Aberdeen confirmed septicaemic listeriosis in a two-week-old Charolais calf. At postmortem examination there was evidence of extensive haemorrhage over the epicardium and the spleen (see figures 2 and 3 at top right) and a multifocal hepatitis. Listeria monocytogenes was isolated from the lung and liver. Access to poorly fermented silage was suspected as the source of infection. The farmer reported three recent deaths in calves of a similar age.

Polyarthritis, loss of body condition, reduced milk yield and pyrexia was reported in a Holstein-Friesian cow aged four years. Serology for Mycoplasma bovis was negative, but Bovine Virus Diarrhoea (BVD) virus was demonstrated.

Alimentary Tract Disease

A six-year-old Holstein cow was submitted for postmortem to Dumfries with a history of abdominal distension before death. The rumen was impacted and the proximal small intestine was distended with gas. Torsion of one section of the mesentery affected one section of the jejunum. It was very congested with blood filled contents. The large intestine was almost empty. This was reported to be the fourth cow to have died with similar clinical signs. Hypocalcaemia (1.7mmol/l; reference range 2.2 to 2.6mol/l) was thought to be secondary to the torsion rather than the cause of gut stasis. Follow up investigations failed to identify any nutritional pre-disposing factors to the condition.

A four-week-old Limousin calf was euthanased after becoming recumbent and dehydrated due to scour. Necropsy revealed thickening of the small intestinal wall and enlargement of the mesenteric lymph nodes. E. coli was isolated from the liver, spleen, kidney and small intestine. Histopathology showed numerous bacteria adhering to the surface of enterocytes on the villi and upper mucosal glands of the large intestine. Changes in the small intestine were less marked. A diagnosis of attaching and effacing E. coli was made.

Reproductive tract conditions

Ayr isolated Bacillus licheniformis from the foetal stomach contents of two near-term aborted calves from a farm on which six cows had aborted over a two-month period. They also recovered the same organism from the stomach contents and lung of another near-term aborted calf from a different farm, on which six abortions had occurred over a six-week period. A suppurative pericarditis was found on histopathological examination of one foetus. The value of histopathological examination was further demonstrated in another abortion investigation when a severe suppurative placentitis associated with fungal hyphae was noted, allowing a diagnosis of mycotic abortion to be made. Isolation of a fungus from placental material would have been inconclusive in the absence of supporting histopathology.

Mycosis was also diagnosed as the cause of abortions in two beef herds in the Borders. In the first herd, an eight-month-foetus was submitted from which Aspergillus fumigatus was detected in stomach contents. In the other herd, three abortions and a stillbirth were reported in a group of 100 cows due to calve in March. Submitted material from different abortions included a piece of placenta and a foetus. No fungi were detected in smears or cultures from the placenta or the foetus. However histopathology revealed myocardial haemorrhages and hepatocyte necrosis consistent with anoxia due to placental failure. There was also a severe necrotising placentitis and fungal hyphae were demonstrated in the lesions.

Histological lesions in the liver indicative of Bovine Herpes Virus type 1 (BHV1) infection was found in a foetus from which Bacillus mycoides was isolated from the stomach contents and viscera. The tissues were subjected to immuno-cytochemistry for BHV1 and this confirmed the presence of the virus in the lesions. No respiratory disease has been recognised in the beef herd from which the abortion material was submitted. This is the first time that BHV1 infection has been confirmed as the cause of abortion on the basis of foetal examination at St Boswells and only the second time that this has been achieved in Scotland. The first was in 2006 at Dumfries. The SAC questions whether a new strain of BHV1 was now active in the country, capable of producing the characteristic foetopathy described in North America.

Abortion due to Campylobacter fetus fetus was diagnosed twice during the month at Dumfries. In the first case the history was of a single abortion from which Salmonella Dublin was also isolated. On the second dairy farm there had been a series of 16 abortions from 90 cows over a period of two months. The owner suspected that other cows had also aborted without the foetuses being found. The submitted foetus was of four to five months gestation, although losses had occurred at various stages. Only cows on one side of the shed were affected with no abortions in the cows on the other side. A bull was running with the cows on the affected side. Despite being a young bull this was considered the likely source and vector of infection.