222..4 Lameness in sheep

Question 1

What are other names for scald? What is the causative agent?

Answer 1

Scald = strip/interdigital dermatitis
Causative agent: Historically believed to be Fusobacterium necrophorum ; this is found in healthy sheep too, so possible opportunistic role

Question 2

Clinical signs of scald

Answer 2

• inflammation of skin between claws
• reddening
• paste
• white/grey scum
• sore - sheep with resent part of the digits

Question 3

What is the commonest cause of lameness on sheep farms?
a) Scald
b) CODD
c) Footrot
d) Trauma

Answer 3

c) Footrot

Question 4

What is the causative agent of footrot?

Answer 4

• For the purposes of this question: Dichelobacter nodosus
• Historically, it was believed that Fusobacterium necrophorum caused scald, and Dichelobacter nodosus then became involved, leading to footrot
• Evidence now suggest D. nodosus may be first to invade in poor conditions, with F. necrophorum following opportunistically

Question 5

Clinical signs of footrot

Answer 5

• smell
• grey ooze
• under-running of the hoof horn hear to the skin between the claws/under-running of the horn anywhere

Question 6

True/false: treatment/management of interdigital dermatitis (scald) and footrot as one diseases results in lower prevalence of lameness in the flock.

Answer 6

False
Sheep with scald may be the most infectious sheep.
It is not enough to only treat the sheep with footrot; must treat those with scald too.
Treatment = treat sheep and separate them from the flock to prevent environmental accumulation of D. nodosus and further sheep-sheep transmission

Question 7

Interdigital dermatitis is also known as…

Answer 7

scald

Question 8

Which of the following diseases begins with lesions at the coronary band?
a) Footrot
b) Scald
c) CODD

Answer 8

c) CODD

Question 9

Clinical signs and morbidity of CODD

Answer 9

CODD = contagious ovine digital dermatitis
* Highly invasive and painful
* Starts with lesions at the coronary band
* There is rapid invasion and under-running of the hoof wall
* There may be no involvement of the interdigital space
* In a naïve flock, >30% of the flock may be affected in the first year CODD is introduced; this then settles to 2% lame sheep

Question 10

Describe how you would differentiate CODD from footrot

Answer 10

CODD starts with a lesion at the coronary band rather than between the digits as with footrot

Question 11

Describe the aetiology of CODD

Answer 11

Spirochaetes/treponemes are commonly involved
Infections are often mixed, including D. nodosus
It can be hard to differentiate footrot from CODD based on pathogens present, but treatment is often the same anyway

Question 12

Treatment and management of CODD

Answer 12

• Requires long-acting injectable antibiotic (long-acting amoxicillin/oxytetracycline, could use macrolides like tilmicosin but NOT first line)
• Spray all 4 feet even if lesions only on one; the parenteral antibiotics are often needed for added penetration
• Isolate lame sheep so they can’t infect the rest of the flock
• NSAIDs -> none licensed in sheep but meloxicam fine
• Treat individual sheep rather than the whole flock. Whole flock treatment not appropriate and not justified under antimicrobial stewardship.

Question 13

What factors are associated with lower CODD levels?

Answer 13

• Not buying in sheep
• Isolation of sheep returning to the farm
• Avoid use of summer grazing away from the farm
• Prevention of ewes mixing with neighbouring flocks
• Examination of feet prior to purchase
• Use of footvax (this is for footrot, but seems to be protective for CODD too, although we don’t know why yet)
• Quarantine is important -> introduction of CODD is linked to poor biosecurity

Question 14

True/false: footbathing provides just as good control of CODD as parenteral antibiotics of individual sheep.

Answer 14

False
Parenteral antibiotics provide better control of CODD

Question 15

True/false: routine foot trimming at least 2x per year is recommended for good control of CODD.

Answer 15

False
Routine foot trimming twice a year is associated with increased risk of CODD.