Veterinary Services

Pulmonary thromboembolism was diagnosed in a three-year-old dairy cow submitted to Ayr. It showed milk-drop and fever for two weeks and died unexpectedly after treatment with antibiotics and an apparent improvement. At postmortem examination blood was evident at the mouth, nostrils and in the trachea. Severe emphysema and areas of consolidation were seen in the lungs. Multiple, large thrombi were noted in the blood vessels. Histopathology of the lungs confirmed extensive fibrosis, congestion, haemorrhage, fibrin exudation and a large amount of thrombotic material. The liver had a nutmeg appearance and histopathology revealed portal fibrosis, biliary hyperplasia, periacinar congestion, haemorrhage and degeneration consistent with acute circulatory failure. SAC considered the pulmonary thrombo-embolism likely to have followed a primary thrombosis of the posterior vena cava.

Parasitic diseases

 
A group of eighteen four to five-month-old Holstein heifers from a Dumfriesshire farm were not thriving.  They were treated with an anti-coccidial drug at eight weeks of age. Following a second dose all but one began to improve.  The remaining calf was submitted for postmortem examination and weighed only 62kg.  A coccidial count of 350 oocysts per gram of faeces was found.  No active coccidiosis was found on histopathology but crypt abscesses were present suggesting secondary bacterial infection.  In addition there was a significant interstitial nephritis.  SAC considered that these factors would account for the failure of the calf to improve following treatment.

Alimentary tract disorders

Johne’s disease was diagnosed on 20 occasions by Dumfries. These were evenly split between beef and dairy cattle.  It was identified twice at post-mortem examination; in a five-year-old Holstein cow and a five year old Limousin cross cow.  In both cases the history was of condition loss and scour.  At postmortem examination the lower jejunum and particularly the ileum were thickened and corrugated (figure 1 - see top right-hand side).  In one case the mesenteric lymph nodes were also enlarged.

Respiratory tract diseases

Two six-month-old calves were submitted from a Fife beef unit for postmortem examination. Both died following a short illness.  The main finding in both animals was a severe purulent laryngitis and tracheitis.  This was associated with a secondary pneumonia, with marked consolidation in an anteroventral pattern. An acute infectious bovine rhinotracheitis (IBR) viral infection with secondary bacterial pneumonia was suspected.  This was confirmed when Bovine herpesvirus type 1 (BHV1) was detected by fluorescent antibody test (FAT) examination of tracheal tissue from both calves. Pasteurella multocida was subsequently isolated on culture of the pneumonic lung and trachea in each case.

Two seven-month-old fattening bulls from a unit in Ross-shire died from IBR. Gross postmortem examination and histopathology showed acute fibrinosuppurative bronchopneumonia and acute necrohaemorrhagic tracheitis. FAT’s were positive for BHV1 and BHV1 viral antigen was detected by PCR. Histophilus somni was also recovered from lung tissue.

Reproductive tract conditions

 
Dystocia due to foetal oversize was diagnosed in a stillborn calf submitted from a beef suckler farm in Perthshire.  It was the third stillbirth in a group of 15 cows.  The carcase was extremely large, weighing 52 Kg, and stained with meconium across the perineum. The head and neck were swollen due to marked oedema. Blood was noted in both shoulder joints. The lungs were partially expanded and there was evidence of inhalation and ingestion of meconium. The brain was markedly congested.  There were no significant bacteriological or serological findings. Histological examination of the brain, lung, thyroid, liver and placenta showed a degree of congestion but no other abnormalities.

Circulatory system disorders

A nine-month-old Charolais cross bull from an Aberdeenshire unit died unexpectedly after responding to treatment for pneumonia a few days previously. It was one of a batch of 25 animals that arrived on the unit a month previously. The group   required metaphylactic treatment following an outbreak of pneumonia a week after arrival. Postmortem examination revealed numerous, pale necrotic foci in the myocardium from which Histophilus somni was isolated. The lung tissue was firm and congested and there was severe interlobular and interstitial oedema consistent with cardiac failure.

In a similar case, also from Aberdeenshire, a pluck was submitted from a 12-month-old stirk. The group had received metaphylactic treatment 12 days previously following at least two fatal cases of pneumonia.  There was generalised severe pulmonary interlobular oedema but no gross evidence of consolidation and only very mild congestion. There were multiple subendocardial and myocardial abcesses of varying size in the left ventricle adjacent to the left atrioventricular (AV) valve with the largest abscess protruding into the ventricular lumen immediately adjacent to the left AV valve (figure 2 - see top right-hand side). A growth of Histophilus somni was isolated in culture from the abscesses.

Musculoskeletal conditions

A number of Limousin cross, suckled calves from an Aberdeenshire farm aged from one to three months presented with sudden onset lameness. Some responded to antibiotics but others progressed to necrosis at the toe, under-running of the sole and septic arthritis. An amputated digit was submitted from one case. There was thinning and separation of hoof horn at the toe and a 2 cm abscess with thick green pus in the pedal bone. Arcanobacterium pyogenes and Peptostreptococcus species were isolated on culture. The case was very similar to one previously investigated by SAC  where the lameness was thought to be trauma induced due to scrabbling by calves being  handled through a cattle crush. The history in this case was also of handling through a cattle crush a few weeks previously.