Veterinary Services

Examination of diagnostic data recorded by SAC VS over the last 14 years indicates a clear increase in the diagnostic rate for ovine parasitic gastroenteritis (PGE) (Fig  5 - see top right-hand side).  This is true for diagnoses of nematodirosis and those of “non-specific” PGE due to other trichostrongylid nematodes. The SAC considers that the trend in recent years towards an earlier spring and the generally higher temperatures and rainfall over the summer months could be contributory factors.   These conditions enhance the development and migration of third stage (L3) infective larvae on pasture, leading to higher recorded levels of disease, particularly in grazing lambs.  It is also possible that anthelmintic resistance may be responsible for an increase in clinical disease in some areas of the country.

Eight incidents of Johne’s disease were recorded in Scottish flocks. In one typical case, two Scottish blackface ewes were submitted for postmortem examination from a flock where every year two to three animals are culled due to emaciation.  In both animals the mid to distal jejunum, ileum and caecum were thickened and pigmented orange.  Ziehl-Neelsen stained mucosal smears were positive for the presence of acid-fast bacteria confirming the diagnosis.

Septic peritonitis was diagnosed in a four-year-old mule ewe found dead at grass. A large volume of yellow turbid foetid peritoneal fluid and extensive deposits of yellow fibrinopurulent material were found.  The latter was attached to the surfaces of all the abdominal organs, the abomasum and intestines being most severely affected.  The source of this pathology was found to be a ruptured necrotic ulcer at the extremity of the caecum.

The shepherd reported 26 of 294 ewes in a Dumfriesshire flock as having firm swellings under their jaws. A number of ewes also lost weight and several showed signs of dysphagia.   Lambs with a similar problem had been noticed some ten days earlier and two ewes with swollen throats were discovered when the group were wormed five days previously.  On postmortem examination of an affected individual there was no obvious traumatic damage. However, there was swelling of the pharynx and inter-mandibular space, with necrosis, oedema and haemorrhage within the muscle.   A Fusobacterium species and Mannheimia haemolytica were isolated on culture.  The former organism was considered to be the cause of the cellulitis and SAC postulated that the infections had resulted from injury caused by a dosing gun.

Respiratory tract conditions

Twenty blood samples were collected at random from a flock where ovine pulmonary adenocarcinoma (OPA) and maedi-visna (MV) had previously been diagnosed following the postmortem examination of a thin ewe.  A total of 14 of these 20 bloods were found to be positive for antibody to MV in the AGID test, suggesting that infection within the flock was widespread.  Investigations continue.

Nervous system disorders

Nervous signs resulting from brain abscesses were seen in two Aberdeenshire flocks. In the first case, a six-year-old recumbent halfbred ewe was presented. The history was of significant weight loss over two months.  The ewe was able to rise after repeated attempts but remained unsteady.  It also tended to knuckle at the fetlocks, evidenced by excessive wear on the anterior aspect of the hoof walls.  Also apparent was a kangaroo-like gait and a tendency to deviate the neck to the left.  On necropsy bilateral cerebellar abscesses containing green pus were present. A scant mixed bacterial growth including a Staphylococcus species was isolated on culture from the right cerebellar abscess, and no bacterial growth was obtained from the left side. On neuropathology there was also an abscess compressing the tissue of the medulla. This was surrounded by a thick fibrous capsule which was diffusely infiltrated by mononuclear cells, indicating that it was a chronic lesion.

In the second case, five Cheviot lambs from a group of 1,100 purchased from Sutherland presented with nervous signs and one death. Antibiotic treatment resulted in a rapid but incomplete improvement in the remaining animals. One of the live affected lambs was submitted for postmortem examination. It had a head tilt to the right of approximately 45 degrees (Fig 6 - see top right-hand side). It was ataxic and collapsed when startled.  On necropsy there was a small area of abscessation affecting the right ventral cerebellum, with green pus present. A growth of a Peptostreptococcus species was isolated on bacterial culture. 

Skin diseases

The shepherd of a flock in Fife reported that approximately 25 per cent of a group of 850 purchased lambs were affected by discharging facial swellings.  An affected live lamb was submitted for examination. It was depressed and pyrexic, although in reasonable bodily condition.  Most striking however was the gross enlargement and crusting of the lips (Fig 7 - see top right-hand side).  In addition there was extensive tissue necrosis and shedding of the skin surface over the worst affected areas.  Smaller granulomatous lesions were also noted around the eyes.  Bacterial culture of the soft tissues produced a pure growth of Bibersteinia trehalosi. Orf virus DNA was detected by PCR examination of the same samples.  Contagious pustular dermatitis with secondary bacterial infection was diagnosed.