Sheep & Goats

Question 1

Lameness in sheep and goats due to infectious footrot is associated with wet conditions. What microorganism is considered essential for the disease to occur?

Dichelobacter nodosus
Brucella ovis
Campylobacter jejuni
Corynebacterium pseudotuberculosis
Fusobacterium necrophorum

Answer 1

Answer: Dichelobacter nodosus

Explanation
Formerly called Bacteroides nodosus, this organism is the key to diagnosing infectious (contagious) footrot.
Fusobacterium necrophorum is also often present as a secondary invader in cases of footrot.

Question 2

A 2-year old registered Suffolk sheep has developed weight loss, nervousness, and pruritus, resulting in loss of much of its wool (see image). It has recently developed ataxia and teeth grinding. On the basis of these clinical signs you make a tentative diagnosis of scrapie. If scrapie is confirmed, what is the best approach to managing the flock?

Treat affected animals for 2 weeks with IM tetracyclines
Use stem cell therapy to insert the PrP gene into affected animals and related animals
Use corrals and pastures where the affected animal had been only for lambs under a year of age for the next year
Cull positive animals and treat all others in the flock with immunostimulants
Cull positives and breed for resistant flock based on pedigree

Answer 2

Answer: Cull positives and breed for resistant flock based on pedigree

Explanation
Scrapie is a spongiform encephalopathy, caused by a prion. The PrP gene appears to play a role in susceptibility.

Using known pedigrees (breed only unaffected animals) or genetic testing, a resistant or less susceptible flock can be bred. Affected and related animals should be culled and destroyed, as the prion may otherwise spread the disease.