Lameness can be a cause of great concern for sheep farmers. It is estimated to cost the Irish sheep industry €5 million annually.
It has a direct effect on production (20% reduction in body condition score) and welfare (lameness is painful) and knock-on effects on fertility and productivity through reduced conception rates.
Footrot is the most common cause of lameness in sheep and is present on over 90% of farms.
It is highly contagious (lame sheep or lambs being the main source) and caused by two different bacteria; namely Dichelobacter nodosus and Fusobacterium necrophorum. The latter is also responsible for scald.
Footrot is typically characterised by a distinct foul smell and under-running of the hoof wall. Infection can occur at any time throughout the year, however outbreaks tend to happen more frequently in spring and autumn when underfoot conditions are less favourable.
It is worth mentioning two other common causes of lameness in sheep; scald and contagious ovine digital dermatitis (CODD).
Scald; often seen in lambs, is recognised by reddening and inflammation in between the hooves. It can be managed by appropriate foot-bathing. It is worth noting however that it is often the precursor for footrot.
CODD however, is a much more severe cause of lameness. It starts at the front of the foot where the hoof meets the hair and spreads aggressively into the hoof. It can result in complete loss of the hoof wall and permanent lameness. More than one cause of lameness may be present in a flock at any one time.
The following five-point plan has been successfully used to control lameness in sheep.
Prompt treatment is a must. Speak to your vet regarding the correct treatment for the different causes of lameness. Foot trimming should be kept to a minimum.
2. Avoid spread
Footrot and CODD are extremely contagious and spread from sheep to sheep, particularly at high traffic areas (such as troughs). It is good practice to remove lame sheep/lambs from the rest of the flock until recovered.
It is also worth noting that the bacteria responsible for footrot can survive on pasture for 14 days.
3. Quarantine new sheep
Ideally rams/sheep/lambs should not be introduced to a flock for a minimum of four weeks after arrival on farm; this allows time for vaccination, dosing, lameness observation etc.
Lame sheep should never be brought into a flock.
The footrot vaccine contains ten different strains of the bacteria responsible for footrot. Vaccination has been shown to significantly reduce the level of lameness caused by footrot. Research has also shown that by controlling footrot, the incidence of CODD can be reduced.
Sheep/lambs must receive a two-dose primary course six weeks apart, and then a single booster before the next period of risk. A six-monthly booster is recommended in flocks with constant challenge.
It is a 1ml dose to be give under the skin in the side of the neck only. Speak to your vet for more information about the footrot vaccine.
5. Cull repeat offending sheep
Cull the repeater offenders. Any sheep/lambs that have been treated (correctly) twice previously are unlikely to ever respond successfully and are a constant source of infection for the rest of the group.
It is not uncommon for 10% of sheep/lambs to be lame which results in a substantial impact on that flock’s performance. Whether we are talking about breeding ewes or store lambs, lameness is worth controlling and a prevalence of two percent is both tolerable and achievable.
Written by Cara Sheridan, ruminant technical vet, MSD Animal Health
For more information on lameness in sheep and how best to tackle this issue on your farm, click here.