Veterinary Services

Nutritional and metabolic disorders

Copper, cobalt and selenium deficiency were commonly diagnosed throughout December. In one such case a herd of 70 suckler cows in Ross-shire reported that all cows were affected with weight loss and were scouring. The animals were housed and being fed grass silage, arable silage and hay. There was no evidence of fasciolosis or protein deficiency. Trace element analysis revealed evidence of selenium deficiency with four of five cows blood-sampled having glutathione peroxidase (GSH-PX) results ranging from 4.5-16.5 u/ml RBC. The mean level for the five cows was 15.2u/ml RBC (reference range > 23u/ml RBC).

Generalised and systemic conditions

Animals persistently infected (PI) with bovine viral diarrhoea virus (BVDV) were commonly detected in December.

At the Inverness Centre an eight-week-old Limousin-cross bull calf from a holding in Ross-shire was diagnosed with mucosal disease, the third young calf to die following relapsing episodes of diarrhoea, with dysentery at times. The calf which weighed only 43kg showed interdigital ulceration and one coronet had detached from one of the hind feet. The nose and mouth were hyperaemic and the oral mucosa and tongue were covered with a thick diphtheritic layer. Numerous ulcers were present on the oral mucosa and linear ulceration was evident along the length of the oesophagus. The reticulo-ruminal mucosa also showed multiple erosions and ulcers.

A four-week-old Limousin cross bull calf was submitted to the Dumfries Centre for post mortem examination from a group with a history of scour and pneumonia problems over a period of three weeks. Gross pathology indicated pneumonia and pleurisy with some thickening of the intestinal mucosa. Salmonella Dublin was isolated from this case in septicaemic distribution and there was evidence of hypogammaglobulinaemia based on zinc sulphate turbidity (ZST) testing. In addition BVDV was isolated from the thyroid gland. A blood sample taken previously had however proved negative for BVD antigen and antibody. BVD viral DNA was subsequently identified in the blood sample by polymerase chain reaction (PCR), and it was concluded that this was most likely to be an acute infection with BVDV, with low levels of virus in the circulation undetectable by the BVD antigen enzyme linked immunosorbent assay (ELISA).

Reproductive tract conditions

A stillborn calf submitted to the Dumfries Centre from a suckler herd was one of two abortions to occur at the end of the autumn calving period. The thyroid gland weighed 123g (see Figure 1; click on link in right-hand column) and histopathological examination of this tissue failed to identify any normal thyroid follicles and no colloid was present.

The thyroid iodine content was 424 mg/kgDM (reference range 1200-2000), confirming a diagnosis of iodine deficient goitre. BVD virus was also isolated from the thyroid gland and foetal fluid proved seronegative for BVD, suggesting infection prior to the development of the calf’s immune system.

Respiratory tract conditions

Table 1 : Bovine Respiratory Disease 1998-2005

During 2005 the commonest specific pathogens associated with respiratory disease in cattle were Pasteurella multocida, Mannheimia haemolytica, infectious bovine rhinotracheitis (IBR) due to bovine herpesvirus 1, respiratory syncytial virus (RSV) and Histophilus somni the prevalence of which latter pathogen has increased steadily since 1998.

On a farm in the Scottish Borders a ten-month-old Aberdeen Angus bull calf which died after two days of progressively worsening lethargy and anorexia, was submitted to the St Boswells Centre for post mortem examination. Approximately 40 of the 600 housed calves around this age in the affected group were said to be coughing. There had been previous experience of bovine herpes virus type 1 (BHV1) infection on this farm and the owner suspected that the pathogen might also be responsible on this occasion - although all the calves had received a full course of a multivalent vaccine that included a BHV1 component. On post mortem examination the submitted calf was found to have bilateral fibrinous pleurisy, pneumonia and pericarditis. No specific pathology was detected within the upper respiratory tract. Subsequent bacteriological cultures identified a pure growth of Histophilus somni (formerly Haemophilus somnus).

At the Thurso Centre parasitic bronchitis due to Dictyocaulus viviparus (lungworm) was the cause of two deaths and severe coughing in 15 to 18-month-old cattle in a beef unit. The animals had received anthelmintic boluses at turnout in May but no treatment since, and were housed at the start of December without anthelmintic therapy.

Pneumonia due to respiratory syncytial virus (RSV) was diagnosed in two Aberdeen Angus cross calves submitted to the Dumfries Centre. The calves had been housed since purchase in early November and experienced a group outbreak of pneumonia over the Christmas period. Gross pathology was consistent with RSV disease and the virus was detected by fluorescent antibody testing (FAT) of lung tissue. In addition, Histophilus somni and Mycoplasma bovis were isolated from both cases.

Musculoskeletal conditions

An eight-month-old Belgian Blue calf, which was seen with bloat, but still eating and died the next day, was submitted for post mortem examination to the Perth Centre. The 450 kg steer was in very good condition with multiple petechiation throughout the soft tissues on the right side of the carcass from the neck along the right flank and right spinal musculature. A region of the distal right ventricle (approximately 2 cm. in diameter ) had a black necrotic appearance and was firm to touch. A Gram smear of the affected myocardium revealed Gram-positive bacilli and FAT proved positive for Clostridium novyi. C.novyi was subsequently isolated from anaerobic culture of affected cardiac muscle. Histopathology revealed focal areas of inflammation and associated necrosis of cardiac muscle associated with large numbers of clostridial organisms. These findings were consistent with a diagnosis of clostridial disease with a primary lesion in the heart.

A two-day-old Belgian Blue calf was submitted to the Dumfries Centre with a history of being unable to stand, despite a caesarean birth. All six calves born recently to the group had been slow to stand. The skeletal muscles appeared to be a mottled white colour. Acute myodegenerative changes were noted in the skeletal, diaphragm and intercostal muscles with a significant variation in the diameter of the muscle fibres. A diagnosis of myopathy was made despite liver vitamin E and selenium levels which were considered adequate. The calf had been injected with vitamin E and selenium at birth, which may have affected these levels.

Toxic conditions

Lead poisoning was confirmed by examination of blood samples from two suckled calves aged around six weeks at the Ayr Centre. Blood lead levels in the affected calves were 8.28 and 10.07 m mol/l (reference figure: < 1.21). Affected calves were showing bruxism (teeth grinding) and head pressing. The source of the lead was a painted wall in a silage pit that had a lead level of 15.4 % in the paint. Assuming a lethal dose of lead of 0.22 g/kg liveweight then a 50 kg calf would only need to ingest 71 g of this paint to cause death and less to cause poisoning.

Voluntary restrictions and further blood sampling to monitor the situation were agreed between the Food Standards Agency and the farmer. Other calves in the group subsequently showed blood lead levels between 0.07 – 1.25 m mol/l (reference range: < 1.21). Both affected calves recovered with treatment but are still showing blood lead levels above the reference range.

Circulatory system disorders

A heart was submitted to the Inverness Centre from a two-month-old Limousin cross heifer calf, which had died relatively suddenly. The calf was found in extremis and died when being examined. The liver and heart were grossly enlarged and the heart was found to have a large atrial septal defect, extending the entire depth of the atria. The ventricular septum also appeared shorter than normal though the ventricular chambers were separate. The calf was also deficient in vitamin E with a level of 1.0 mol/l (reference range 3.0-18.0umol/l).