Veterinary Services

Babesiosis was diagnosed twice during the month.  In one case examination of a blood smear from a home-bred, three-year-old, Limousin-cross cow from the Falkirk area revealed Babesia divergens parasites in the erythrocytes.  SAC C VS considered babesiosis is an unusual finding in the central belt of Scotland.  Haematuria had been noticed three days previously and the mucous membranes were pale but there was no evidence of jaundice.  The cattle had access to bracken and tick numbers were considered to be unusually high in the field.

Generalised and systemic conditions

Diagnoses of clostridial disease were recorded in spring born suckled calves across Scotland.  On one farm In Dumfries and Galloway two Limousin calves were found dead over a six day period.  Three other calves were reported to be stiff.   Gross pathology included multiple gas bubbles within the liver and diaphragm.  The diaphragm and myocardium also appeared dark in colour and the spleen was enlarged.  Clostridium chauvoei was detected by fluorescent antibody testing (FAT) and culture from the heart.

   
Two 12-month-old suckled calves were submitted for postmortem examination from a unit in Perthshire.  Gross examination revealed widespread subcutaneous petechiation, dark, haemorrhagic musculature in the neck region and a friable and gassy liver.  FAT examination of muscle tissue identified Clostridium novyi.
A three-month-old Charolais-cross calf from the Borders was found in lateral recumbency exhibiting opisthotonus. Following euthanasia, histological examination of the brain revealed very severe areas of malacia and perivascular leakage in the white matter. These changes were consistent with focal symmetrical encephalomalacia (FSE) caused by epsilon toxin of Clostridium perfringens.

Numerous investigations of increased incidence of neonatal mortality in suckler herds were investigated by St Boswells.   The main findings were omphalophlebitis, evidence of poor colostral immunity, meningitis and joint ill.  In one 300 cow herd there were 20 deaths in the course of the calving season since mid May. Three calves received for necropsy showed the range of pathology listed above. The high level of neonatal sepsis was not explained.  Several other cases of omphalophlebitis were diagnosed in suckled calves aged between six weeks and two months. These animals were generally in poor body condition.
 
A 15-month-old British blue-cross bullock from a Dumfriesshire farm was found dead. Postmortem examination showed haemorrhage into the sinuses and trachea but no evidence of lung pathology.  The lymph nodes of the neck were enlarged and contained petechiae as did the thymus.  One area of the jejunum was haemorrhagic.  Cytopathic bovine virus diarrhoea (BVD) virus was isolated from the sinus mucosa and spleen indicating that this was a case of mucosal disease rather than a primary viraemia. Immunohistochemistry on a range of tissues also showed the distribution of the virus was consistent with mucosal disease.  A second case of mucosal disease on the farm was confirmed by blood testing. Blood sampling 45 replacement dairy heifers detected BVD viraemia in one case.  The herd vaccinates for BVD, but no action was taken to remove viraemic animals from the herd.   

Alimentary Tract disorders

Postmortem examination of a 30-month-old dairy heifer showing chronic ill thrift with no scour over a three month period revealed marked thickening and corrugation of the intestinal mucosa, extending from the level of the jejunum to the terminal ileum. Zeihl-Neilson-stained smears from different levels of the ileum were all positive for acid/alcohol-fast bacilli, forming clumps typical of Mycobacterium avium subsp. paratuberculosis, confirming a diagnosis of Johne’s disease.

A three-month-old Charolais heifer calf that died following a history of scour and ill-thrift was submitted to Ayr for postmortem examination.  Subcutaneous and internal fat was yellow-tinged and the liver was enlarged with necrotic foci (figure 1 - please see top right-hand side).  Mucosal ulcers were noted in the abomasum and small intestine, serosal haemorrhages were present, and there was a localised peritonitis with adherence of bowel loops.  On histopathology severe necrotic, haemorrhagic enteritis, necrotising and ulcerative abomasitis and fibrinous peritonitis were evident. Screening for BVD and Salmonella species proved negative and a diagnosis of idiopathic necrotising enteritis was made.

A group of 56 dairy bred calves from a Dumfriesshire farm were turned out for the first time in April.  They were wormed and treated for coccidiosis.   Despite this they lost condition and some became weak and recumbent before death.  Scour was reported but no diagnosis was reached on submitted samples.  By the end of June 14 calves had died.  At postmortem examination a submitted calf had nasal crusting with ulcers and erosions on the tongue.  There was a severe pharyngitis and oesophagitis.  No worms or coccidia were detected and screening for BVD virus was negative.  On histopathology the mucosa of the small intestine was distorted and hyperplastic.  Salmonella Dublin was isolated. SAC C VS considered the ill thrift was secondary to chronic salmonellosis. 

Review of bovine respiratory diseases 1998 to 2008

 
Respiratory disease in housed cattle is usually associated with viral and/or bacterial infections. The most commonly diagnosed viral pathogens are  Bovine Herpes Virus 1 (BHV1), Bovine Respiratory Syncitial virus (BRSV) and ParaInfluenza virus 3 (PI3), while Histophilus somni, Mycoplasma bovis, Mannheimia haemolytica and Pasteurella multocida are the most commonly diagnosed bacterial causes. Arcanobacterium pyogenes is occasionally isolated from diseased lungs, however it is a ubiquitous organism that colonises devitalised tissues and should therefore not be regarded as a primary cause of respiratory disease in cattle.  A review of surveillance data gathered over the past ten years indicates trends in diagnosis rates that can help inform decisions regarding vaccination for the forthcoming housing period.

Diagnosis rates of M. bovis and H. somni have remained fairly constant throughout the past decade, and there has been a small decrease in the percentage of outbreaks where M. haemolytica or P. multocida was diagnosed (figure 2 - please see top right-hand side).

The diagnosis rates of BRSV, PI3 and BHV1 infections show a decrease (figure 3 - please see top right-hand side). SAC C VS proposes that this reduction may indicate that the clear advice on prevention and control of these infections is being adopted by the industry. Nevertheless, SAC C VS recommends the continued promotion of respiratory disease vaccines in housed cattle, along with good management practices, in the prevention of bovine respiratory disease.

Musculo-skeletal conditions

Fifteen eight-month-old Holstein bulls on a Dumfriesshire farm were housed on straw and fed an ad lib diet of oats, rape and soya for four to five months.  Silage was also available but no minerals were added to the ration.  Two bulls became recumbent and were euthanased on welfare grounds.  In the one case the left hock was swollen with an open wound through which a fracture of the calcaneus was visible.  The bone fragment had been avulsed by the achilles tendon (figure 4 - please see top right-hand side).   Adhesions were visible around the site suggesting that this was the original injury that caused the recumbency.  In addition there was swelling below the right stifle with an area of fresh haemorrhage and a fracture of the proximal tibia.  The growth plates appeared grossly normal but the bones were soft and easy to saw through. Nutritional osteodystrophy was diagnosed. Oats, rape and soya are devoid of vitamin D while oats are also low in calcium.