Veterinary Services

Nutritional and metabolic disorders

Copper deficiency was diagnosed by the Thurso Centre in an eight-month-old stirk which was found recumbent with painful joints. The copper level in plasma was not detectable. The animal resented being touched and gave the appearance of aggression due to pain. Treatment with parenteral copper resulted in an improvement in seven days when the animal was standing and approachable. A similar manifestation of copper deficiency has been previously recorded in the far north of Scotland. 

Alimentary tract diseases

Paratuberculosis

The number of outbreaks of paratuberculosis in Scotland (Johne’s disease) has increased for the fourth year running. Since the widespread disruption in diagnostic submissions in 2001, there has been a 32% increase in submissions from cattle screened for Johne’s disease from 2002 to 2004 and a 23% increase in disease outbreaks to 3376 (figure 1: see PDF link in right hand column) . A number of national initiatives over this period may have increased awareness of the disease and partly account for this increase. Namely, in 2001 Defra published a report on the surveillance and control of Johne’s disease and in the same year the Food Standards Agency (FSA) held an industry workshop on the control of the causal agent Mycobacterium avium subspecies paratuberculosis (Map) in milk. This latter initiative was followed up by the publication of a strategy to control Map in milk in May 2002 and the Defra campaign on the control of Johne’s disease in the dairy herd was launched in September 2004.

The seasonal distribution of outbreaks during 2004 is illustrated in figure 2 (see PDF link in right hand column). 

Generalised and systemic conditions

Post mortem investigations were carried out by the Perth Centre into a series of deaths from the same group of cattle. All cattle which were vaccinated against clostridial disease presented as sudden deaths. In the first case, a five-month-old suckled calf, extensive swelling of the pharyngeal soft tissue was evident with pale, florid lesions within the inflamed soft tissue. The right apical lung lobe was consolidated and all airways were full of clotted blood. Histopathology revealed an acute bacterial pneumonia and pleurisy with thrombosis of the septal blood vessels accounting for the blood in the airways. The pharyngeal lesion was described as a clostridial myositis / malignant oedema.

A second case of similar age was bloated with extensive crepitus over the back, rump and proximal limbs. On incision emphysema and oedema of the subcutaneous tissue was noted consistent with blackleg, particularly in the gluteal muscles. The diagnosis was confirmed by isolation of Clostridium chauveoi from affected muscles and histopathology. A third case from the same field was then submitted. This case had no crepitus or bloat, but did have similar lung lesions to the first calf submitted and superficial musculature appeared grossly normal. However, within the deep gluteal muscles lesions consistent with blackleg were evident (confirmed by bacteriology). The affected group of calves were removed from the field in question.

A three-year-old Simmental-cross cow died suddenly in a herd in Inverness-shire. The cow had gross evidence of a diffuse interstitial pneumonia with excess thoracic and peritoneal fluid. The liver contained pale, miliary foci which coalesced in some areas. Profuse growths of Salmonella Dublin were isolated from liver and lung. The affected farm neighbours another which had been experiencing abortions due to Salmonella Dublin. A Salmonella species, under identitification, has been isolated from two water courses on the holding where the cow died. Both affected farms reported that they had experienced a few sudden deaths in cows over the previous few months, but the cause had not been investigated.

Respiratory tract conditions

Parasitic pneumonia was a common diagnosis across Scotland this month. Young-stock were most commonly affected, however there were reports of the condition affecting adult dairy cows.

In a typical case, a two-year-old heifer was submitted for post mortem examination against a background of widespread coughing amongst adult and young cattle both housed and at grass. Extensive pulmonary emphysema with bullae formation was evident throughout both lungs with a moderate number of adult lungworm present in the trachea. Laboratory testing failed to provide evidence of any other respiratory pathogens. In addition to lungworm, adult liver flukes were present and evidence of parasitic gastroenteritis with a worm egg count (wec) of 3,800 trichostrongylid eggs per gram of faeces (epg).

Faeces samples were subsequently submitted from four further animals on the farm with lungworm larvae isolated from one sample.

Infectious bovine rhinotracheitis (IBR) was found to be the cause of sudden onset coughing with conjunctivitis in a dairy herd in northern Scotland with concurrent milk drop. Affected cows were depressed for two or three days and then started to recover, but the milk yield has not recovered to previous levels. The condition was confirmed by fluorescent antibody testing (FAT) from nasopharyngeal swabs of affected cattle. The disease had not previously been recorded in the herd. Sporadic sudden deaths in suckled calves due to pneumonia were recorded in the far north of Scotland.

Respiratory syncytial virus (RSV) was diagnosed by FAT in lung tissue, as the cause of sudden death in an eight-week-old suckled calf at grass. Pulmonary pathology consisted of congestion, emphysema, oedema and partial consolidation with mild pleurisy. In another case a three-month-old calf which presented with respiratory distress and nervous signs died despite treatment. Post mortem examination revealed pneumonia affecting the apical and ventral lobes. Parainfluenza type 3 virus (PI3) was detected by FAT from affected lung tissue and Staphylococcus aureus was cultured from lung and brain. A total of four of ten calves succumbed in a two week period. 

Diseases of the nervous system 

A day old Friesian bull calf, one of four affected calves was submitted to the Dumfries Centre with a history of blindness and incoordination. Post mortem examination identified a severe hydrocephalus and evidence of cerebellar hypoplasia. No infectious cause for the condition was identified.