Johne’s Disease (Paratuberculosis)
· Characterised by emaciation (not chronic diarrhoea, as in cattle.)
· Annual ewe mortality rate is around 5-10%.
· Encountered in all breeds and husbandry systems.
· Caused by Mycobacterium avium subspecies paratuberculosis. This bacterium can survive for many months on pastures (outside of host).
· Clinically infected sheep are infected early in life via faecal/oral route; however, can be acquired in utero. Goats can be a source of the bacterium if co-grazed.
· Clinical Presentation consists of chronic weight loss/low body score (below 1.5), poor fleece condition in middle-aged (3/4 yo) sheep with normal dentition and nutrition. In extreme cases, submandibular oedema (bottle jaw) may be seen.
· Differential diagnoses of chronic weight loss include… poor flock nutrition, fasciolosis, chronic parasitism due to human error or anthelmintic-resistant nematodes or virulent footrot. (group)
· Differential diagnoses of chronic weight loss include… poor dentition, chronic pneumonia, mastitis, chronic severe lameness, pulmonary adenomatosis, intestinal adenocarcinoma.
· Sporadic tumour of the small intestine, causing weight loss and emaciation.
· Clinical presentation consists of low body score compared to flock, fluid in the abdomen (hard to assess, unless ultrasound used to detect peritoneal fluid.
· Euthanasia is necessary- there is no known treatment.
· Infection of the peritoneal lining of the abdominal cavity.
· Usually occurs after a uterine tear caused by excessive manual interference during lambing.
· Clinical presentation depends on the spread of infection across the peritoneal cavity. Sheep with septic peritonitis are dull, depress and anorexic. Sometimes there may be initial abdominal distension due to gut stasis, however inappetance results in gaunt, drawn up abdomen.
· Differential diagnosis include… womb infection (as follows uterine tear), retained foetus, hypocalcaemia or sub-acute fasciolosis.
· Antibiotic treatment is often useless.
Abomasal Emptying Defect
· Uncommon disorder reported mostly in Suffolk sheep but known to present in other breeds. Cause is unknown but thought to be heriditary.
· Clinical presentation includes weight loss leading to emaciation. Increasing abdominal distension especially on the lower right side of the sheep (when viewed from behind).
· Differential diagnosis include poor dentition resulting in lack of fibrous food and result in rumen distension.