Veterinary Services

A total of 41 outbreaks of nematodirosis were recorded by SAC C VS during June. This was down from the 52 cases reported over the same period in 2008.  An eight-week-old Texel-cross lamb was submitted alive for examination at Dumfries. This followed six deaths in the group during the previous three weeks.  As well as scouring, the lamb showed signs of opisthotonus.   When the small intestine was washed out it was not possible to count the Nematodirus battus worms present since they were tangled with a large number of tapeworms.  However, 3,150 N. battus epg of faeces were counted.  Subsequent histopathology carried out on the brain confirmed lesions of cerebrocortical necrosis (CCN) with focal areas of encephalitis. 

Outbreaks of nematodirosis and parasitic gastroenteritis (PGE) were also recorded in Ayrshire and Argyll.  PGE was diagnosed on the basis of a high worm egg count in an Argyllshire flock that reported black scour in three-month-old Texel-cross lambs.  Since these animals recently received a fluke and worm treatment, anthelmintic resistance was suspected and appropriate advice given. 

Chronic fasciolosis was diagnosed in a lowground ewe that collapsed and died despite flukicide treatment. Triclabendazole resistance was suspected in this case and the farmer was advised to use an alternative flukicide.

Cryptosporidiosis was diagnosed in neonatal lambs in two flocks in Ayrshire and Lanarkshire. In one flock three lambs died and the carcase submitted for postmortem examination showed evidence of haemorrhagic typhlitis and colisepticaemia.

Coccidiosis was recorded in two Ayrshire flocks in lambs aged two months.  In one affected flock five lambs died over a short period.  Severe nephrosis and uraemia were evident, along with enteric coccidial lesions, oesophagitis and abomasal ulceration. A diffuse mucoid and haemorrhagic enteritis and typhlitis due to coccidiosis was also evident in a scouring lamb from an Ayrshire flock where the owner reported five deaths in a group of around 200 hill lambs.

PGE was confirmed on examination of a pooled faeces sample from an organic goat herd in Aberdeenshire. Four goats from the herd of 45 were reported to be scouring with evidence of weight loss.

Generalised and systemic conditions

Salmonella Montevideo was recovered in cultures of internal organs from a two-month-old Suffolk-cross lamb submitted for postmortem examination to Aberdeen.  The unit reported neonatal scour and three deaths in a group of 40 ewes and lambs.  The owner was made aware of the zoonotic potential.

Two six-week-old Scottish blackface lambs were submitted alive from a Dumfries-shire flock.  The first lamb had a history of abdominal distension and dyspnoea, while the second lamb appeared increasingly stiff over the previous ten days.  At postmortem examination the first lamb was found to have a pericardial effusion amounting to some 800 ml and a fibrinous discharge was present on the surface of the epicardium.  The liver was swollen and congested and there was a mild ascites. However, the abdominal distension was mostly due to air within the stomachs. SAC VS proposed that this distension was secondary to mouth breathing which was a feature of the reported dyspnoea.  Examination of the second lamb revealed multiple abscesses. These were within the left ventricular wall, subcutaneously over the thorax, in one kidney and within the spinal canal at the level of lumber vertebrae three and four.  Staphylococcus aureus was isolated from the heart of the first lamb and from the abscesses of the second.  Although no ticks were found during the necropsy, SAC C VS suspected that tick pyaemia was the underlying cause of disease in this case.

Alimentary tract disorders

Five ewes in a group of 150 were found dead in a seven day period, prompting the submission of two carcases for postmortem examination at Aberdeen. In both these ewes there was torsion of the small intestine around the root of the mesentery. The ewes had been on the same field for a month, with no management changes. In a similar case, an Ayrshire farm reported six deaths in ewes over a period of two to three weeks.   Deaths were sudden, although some animals were seen to be bloated prior to death. Postmortem examination of an affected four-year-old Scottish greyface ewe revealed abdominal tympani due to torsion of the small intestine at the root of the mesentery.

Following the diagnosis of Johne’s disease in a goat, based on a positive faecal smear, nine other in-contact adult animals were blood sampled.  Six of these were found to be seropositive for Johne’s disease by the ELISA test.

Cardiovascular diseases

A live 14-month-old Scottish blackface hogg was submitted from a Perthshire flock with a history of weight loss over several weeks.  Following euthanasia the heart showed marked, predominantly right-sided enlargement.  On opening the right ventricle, multiple plaque-like lesions were found to cover the endocardium and to extend into the myocardium (figure 3 - see top right-hand side).  The ventricular lumen was dilated and the muscle of the wall thickened, although there was no involvement of the valves.  No equivalent lesions were seen on examination of the left side of the heart.  Further inspection revealed evidence of congestive heart failure, with an enlarged and friable liver, congested lungs and distended kidneys.  Gram-stained smears made from the heart lesions revealed a small number of Gram negative bacilli and subsequent bacterial cultures confirmed a pure growth of Bibersteinia trehalosi.

Mammary diseases

A six-year-old Texel ewe, diagnosed with mastitis and treated with penicillin and streptomycin, failed to respond to treatment and was euthanased.  On necropsy at Edinburgh, the udder was swollen and congested, with cavitations and milk clots present.  A heavy pure growth of Mannheimia haemolytica was isolated from the udder and a light growth of the same organism from the liver, confirming mastitis due to M. haemolytica with secondary septicaemia.

Musculo-Skeletal conditions

A five-year-old ewe from a flock known to have a significant footrot problem was submitted for postmortem examination after being found dead unexpectedly.  At necropsy the ewe was thin. The skin over the knees was abraded, consistent with kneeling to graze. In three of the feet, there was severe ulceration and inflammation of the interdigital tissue with under-running of the sole, consistent with severe foot rot.  Severe acute suppurative pneumonia was observed, mainly in the right lung, and Bibersteinia trehalosi was isolated in pure growth from this site.

Nervous system disorders

Three Scottish blackface ewes from a Dumfries-shire flock appeared sleepy before dying.  A fourth affected ewe was submitted alive in lateral recumbency, apparently blind and with vertical nystagmus.  Following necropsy the brain fluoresced under ultra violet light and CCN was confirmed on histopathology.

Several Texel-cross lambs were noticed to be weak on their hind legs.  One affected lamb was submitted for postmortem examination.  There were no gross findings and delayed swayback was confirmed on histopathology. This was an unexpected diagnosis since, although the farm was known to be copper deficient, the ewes were supplemented with copper in mid pregnancy.

A four-week-old lamb, reportedly displaying neurological signs prior to death, was submitted to Inverness for postmortem examination. An epidural brain abscess was identified and Escherichia coli cultured from the contents. SAC VS considered this to be related to recent tail docking.

Skin diseases

 
Seven rams presented with swellings of the parotid lymph nodes.  In addition, two others had signs of respiratory disease and in general the group was in poorer body condition than expected.  Caseous lymphadenitis was diagnosed in the flock in 2008.  A swab was taken from one of the lesions and Corynebacterium pseudotuberculosis was cultured confirming the suspected diagnosis.