Veterinary Services

Generalised and systemic conditions

Clostridium septicum infection was diagnosed in a Suffolk-cross ewe found dead in an Aberdeenshire flock.  Eleven ewes had died in the few days following handling for vaccination.  The organism was recovered from neck muscle and liver. SAC VS suggested that the use of a dirty needle might have been initiated infection. 

Septicaemia due to infection with Listeria monocytogenes was confirmed in a mule hogg.  Five deaths were reported in the group that was purchased the previous autumn and was fed silage.
A three-year-old ewe from Inverness-shire was submitted following suspicion of death as the result of a sea eagle (Haliaeetus albicilla) attack. Gross postmortem findings were consistent with injury caused by a predator and no other evidence of systemic disease was noted.  Lesions were similar to those reported in other cases of attack by large birds of prey.  Since a breeding population of sea eagles was reintroduced to the west coast of Scotland, local farmers and crofters have complained that attacks, by what is Britain’s largest raptor species, are a significant cause of lamb losses.  A study has now been funded by Scottish Natural Heritage to identify the extent of the problem.  Sixty newborn lambs within the sea eagle’s normal range have been fitted with electronic tags and their fate will be followed over the course of the year.

Toxic conditions
 
Copper poisoning was confirmed in a flock of 12 bluefaced Leicester ewes in which three ewes died over a month.  The liver copper level in the carcase submitted for examination was 10,700 umol/kg (reference range 314 to 7,850 umol/kg) and kidney copper was 3,150 umol/kg (reference range < 787umol/kg).  Trace element boluses were administered to the ewes prior to tupping and concentrates were fed for several weeks.

Alimentary tract disorders

Lamb dysentery was diagnosed in two Ayrshire flocks causing deaths in lambs from three days to three weeks of age. Diagnoses in carcases showing pathognomonic intestinal pathology were confirmed by demonstration of Clostridium perfringens toxin in bowel filtrates by ELISA.  In one case Fusobacterium necrophorum was also isolated from intestinal lesions.  On both farms ewes were vaccinated with clostridial vaccines pre-lambing.   Lamb dysentery was also diagnosed in three, seven to nine-day-old Texel lambs on a farm near Edinburgh.  The ewes in this flock were also said to be fully vaccinated against clostridial disease, although ten lambs died showing signs similar to the three submitted.

Respiratory tract conditions

Perth received three live ewes with a history of chronic weight loss despite worming and treatment with a trace element bolus.   Following euthanasia, necropsy confirmed very poor body condition.  All three ewes showed evidence of a chronic, bilateral purulent pneumonia and pleurisy, with large areas of fibrinous adhesion to the chest wall.  In addition, two of the sheep had fistulae on the left side of the pharynx in which were found bullet shaped foreign bodies, thought to be trace element boluses.  

Reproductive tract conditions

Aberdeen investigated a report of a series of 20 ewe deaths associated with the abortion of rotten foetuses.  Mannheimia haemolytica was recovered from one set of stillborn foetuses submitted.  As this organism is usually associated with sporadic cases of abortion/stillbirth, submission of further postmortem material was encouraged.

Foetopathy due to Listeria monocytogenes was diagnosed on a Lanarkshire farm on which ten lowground ewes had produced stillborn lambs from a flock of 500. 
A one-day-old Texel-cross triplet lamb was submitted alive, the other two foetuses having been stillborn.  The lamb was under-sized, unusually hairy and demonstrated a tremor.   At necropsy there was a small amount of milk in the abomasum and the small intestinal content was blood tinged.  The beta toxin of Clostridium perfringens was detected in the intestinal contents and thoracic fluid, while border disease virus (BDV) antigen was detected by PCR and culture of the spleen.  Lamb dysentery secondary to persistent BDV infection was diagnosed.

Musculo-skeletal conditions

Four outbreaks of neonatal polyarthritis due to Streptococcus dysgalactiae subspecies dysgalactiae were the first such outbreaks recorded in Scotland in 2009.  Aberdeen investigated this condition in a Suffolk-cross flock that reported 40 to 50 cases of lameness and four deaths in lambs. The flock of 600 ewes lambed in an open courtyard, with lambed ewes moved to individual pens before turn out when lambs were 12 to 24 hours of age. The organism was isolated in septicaemic distribution from internal organs and joints from a typically affected lamb. There was also evidence of complete failure of colostral antibody absorption.

Nervous system disorders

Meningoencephalitis due to Listeria monocytogenes was diagnosed in a two-month-old lamb and a two-year-old ewe from flocks in Lanarkshire and Argyllshire respectively.  In the former case other affected lambs were reported to be star-gazing before collapse and death.  In the second outbreak, four recently lambed ewes collapsed with hyperaesthesia and unilateral facial paralysis. The diagnosis was confirmed by pathognomonic neuropathological changes affecting the mid-brain.

The owner of a flock in Perthshire lost six hoggs over the course of one week from a group of 80 to 90. These hoggs were recently moved to a new pasture known to be heavily infected with ticks. Two other sheep in the group displayed a marked tremor when standing. When one of the fatalities was submitted for necropsy the carcase was found be in reasonable bodily condition. Numerous ticks were seen over the limbs and ventrum. No gross lesions were apparent on examination of the viscera. However, histopathological examination of the brain demonstrated typical changes of louping ill.  SAC VS recommended vaccination to the owner.

Focal symmetrical encephalomalacia (FSE) due to the epsilon toxin of Clostridium perfringens was confirmed in a four-year-old Shetland-cross Cheviot ewe found dead and submitted to Aberdeen.  Five deaths had occurred in ewes in good condition in the preceding ten days.  The flock was not on a clostridial vaccination programme.

Skin diseases

Dumfries investigated  restlessness, stamping and signs of pruritis of the flanks and back in a group of yearling Texel rams.  Body condition was not as good as expected.  Although tufts of wool were displaced over their backs, the most significant finding was of scrotal eczema (figure 4 - see top right-hand side).  Chorioptic mange was suspected, but no mites were found on examination of four animals.  Likewise, scab due to Psoroptes ovis could not be confirmed on examination of skin scrapings.  A Dermatophilus infection was identified in only one case.  Although use of an insecticidal dip was advised on precautionary grounds, the group appeared to self cure without any treatment. 

Orf was confirmed in an Angus flock that reported teat lesions in some ewes with lambs less than two months old.  The lesions started as pustules of five millimetres in diameter that developed into thick crusts and led to mastitis in some cases.  All lambs in the flock were vaccinated against orf during the neonatal period and only bought-in ewes were affected. SAC VS suggested a lack of prior exposure to an endemic problem may have been a factor in the outbreak.  A pure growth of Staphylococcus aureus was isolated on culture of the lesions and subsequently orf virus DNA was detected in the submitted sample by PCR.