Veterinary Services

A Scottish blackface ewe was submitted for postmortem examination after several in the group, which was in-bye for tupping, were found dead.  A significant quantity of grain was noted within the rumen, and a pH measurement of 3.6 confirmed a diagnosis of ruminal acidosis.  Concentrates were not being fed, but it was suspected that the sheep gained access to pheasant feed.

Parasitic diseases

Deaths and diarrhoea were investigated in a group of hoggs on an Argyllshire holding, treated with anthelmintic in September and housed at the end of October.  Following a further anthelmintic treatment, parasitic gastroenteritis (PGE) and coccidiosis were diagnosed on the basis of high worm egg counts and demonstration of Eimeria crandallis and E. ovinoidalis oocysts in the faeces.  Benzimidazole resistance was suspected and appropriate advice on control was given.

Acute fasciolosis caused significant losses on nine farms, while chronic fasciolosis was diagnosed on 22 occasions over the same period.   The total number of ovine liver fluke disease outbreaks recorded by SAC C VS during 2009, was the highest annual figure in our records that stretch back for 15 years.

Six of 80 lambs died in one case of acute fasciolosis.  At postmortem examination of a submitted carcase a blood clot was found free in the abdomen, the liver was swollen (Figure 3 - see top right-hand side) and very large numbers of immature flukes were present within the parenchyma.  The size of the flukes (5 to 8 mm) suggested that the infection occurred following a move to winter grazing.

Aberdeen confirmed subacute fasciolosis in a three-year-old Texel cross ewe.  Nine had died in a group of 190 homebred ewes. The sheep were dosed with triclabendazole nine weeks previously. As some of the liver flukes present were estimated to be at least 14-weeks-old, a recommendation was made to check the accuracy of the dosing gun and ewe bodyweight assessment.

Chronic fasciolosis was the most common diagnosis in flocks from Argyllshire and Renfrewshire. The disease was associated with ill-thrift despite flukicide treatment in some cases.

Generalised and systemic conditions

Systemic disease due to Bibersteinia trehalosi was diagnosed in two eight-month-old Scottish blackface lambs. Six deaths occurred in a group of 160 animals over a period of three weeks, including four deaths in a four day period.  All deaths were reported as sudden and no other signs of illness were noted in the affected group. The lambs received a combined clostridial and pneumonia vaccine. Characteristic petechiation and haemorrhages were evident in both carcases and one animal also showed a necrotising oesophagitis. 

A three-year-old mule ewe submitted to Edinburgh was the third from a group of 70 to die after a move on to fodder kale.  Necropsy revealed marked pulmonary congestion and oedema.  The small intestine was largely empty, but a section of jejunum was distended by slightly bloody fluid with mild emphysema of the gut wall.  Clostridium perfringens was isolated from the small intestinal contents and epsilon toxin was detected by ELISA.  Histology of the brain revealed changes consistent with Clostridium perfringens type D enterotoxaemia.

Review of clostridial disease in sheep 2003 to 2009

The two most commonly diagnosed conditions due to Clostridium species recorded in sheep in Scotland are Cl. Perfringens  type  B disease (lamb dysentery) and Cl. perfringens  type D disease (pulpy kidney).  Outbreaks of lamb dysentery are typically characterised by bloody scour and deaths amongst lambs less than three weeks of age. Pulpy kidney is most commonly encountered in older lambs leading to reports of sudden death. A diagnosis is achieved on the basis of a typical clinical history plus a combination of particular changes recorded at necropsy, typical histopathological lesions and the detection of specific clostridial toxins, generally within intestinal contents. 
Over recent years SAC C VS has identified a steady decline in the combined incidence of these most common clostridial diseases (Figure 4 - see top right-hand side).  In 2003 the two conditions accounted for more than ten percent of diagnosable submissions, while in 2009 this figure was less than seven percent.  Since both conditions are largely preventable through routine maternal vaccination, SAC C VS suggests that the widespread adoption of flock health plans may have contributed to the decline in diagnoses.  Farmers should therefore be encouraged to maintain their usual vaccination programmes against clostridial diseases, despite the current pressure that many may feel to cut costs.

Alimentary tract disorders

A Scottish blackface ewe was submitted to Dumfries from a farm where six ewes in good condition were found dead over a period of one month. The abomasal wall was oedematous and friable. An FAT carried out on the abomasum was positive for Clostridium sordellii and Clostridium septicum. Histopathology confirmed a fibrino-necrotic abomasitis with intra-lesional bacteria consistent with a clostridial aetiology.  Neonatal lambs from the same flock died in the spring due to C. sordellii abomasitis.
Paratuberculosis (Johne’s disease) was confirmed when three Scottish blackface ewes were submitted to Ayr for necropsy.  SAC C VS gave appropriate advice on the control of paratuberculosis within this flock with an established history of chronic ill-thrift.

Respiratory tract conditions

Ovine pulmonary adenocarcinoma (OPA) was confirmed twice. In the first case a Scottish blackface ewe submitted from an Ayrshire flock with a history of ill-thrift showed anteroventral pulmonary consolidation and diaphragmatic lobe abscessation. Bibersteinia trehalosi was isolated from the lung. Histopathology also revealed changes consistent with OPA.  In a second flock a cross bred ewe died during a gather.  The carcase was in extremely poor condition and the right lung consisted entirely of OPA tumour mass.  This animal was one of 100 purchased, but not yet mixed with the rest of the flock.  SAC C VS advised that they continue to be run as a separate group, and that no lambs be kept from these ewes as breeding replacements. 

Nervous system disorders

Encephalitis due to Listeria monocytogenes was diagnosed in an eight-month-old Scottish mule lamb. Seven lambs died on the affected farm over a period of six weeks. The animals were housed and fed big bale haylage and concentrate. The haylage was thought to be of fair quality, but was reported to have “white spots” evident.  Clinically affected lambs initially seemed lethargic, held their heads to one side and appeared blind.  In some cases they started circling and finally went into lateral recumbency and died. Isolation of Listeria monocytogenes from the brain stem on direct culture confirmed the diagnosis. 

Six of 200 housed lambs died in five days after developing nervous signs.  Cerebro-cortical necrosis (CCN) was suspected.  However a light growth of L. monocytogenes was isolated from the brain and a diagnosis of listeriosis was confirmed on histopathology.  This group was also on a haylage based diet.