On the treatment, control and elimination of ovine footrot: a comparative review.

Ovine footrot is detrimental to sheep health, welfare and production worldwide. Strategies for management of footrot have varied between countries and regions due to differences in climate, production systems and proportion of positive flocks. Recent research from Great Britain, where >90% flocks have footrot has highlighted that treatment of individual lame sheep within 3 days with parenteral and topical antibiotics, and without foot trimming, results in rapid recovery. This benefits both animal welfare and productivity. Recent evidence indicates that foot trimming into sensitive tissue during routine foot trimming is associated with higher prevalence of lameness, and careful routine foot trimming is not associated with lower prevalence of lameness, rendering this practice void for control of footrot. Fifty percent of farmers in England are now no longer practising routine foot trimming. The lowest prevalence of footrot without elimination is achieved by treatment of sheep with footrot within 3 days of onset of lameness, separation of lame sheep until recovered and rapid footbathing of a flock when an outbreak of interdigital dermatitis occurs. Vaccination and selection of breeding replacements from non-lame ewes contribute to further reducing the prevalence of lameness. Improving control of footrot has occurred between 2004 and 2013: the global mean prevalence of lameness in sheep has halved from 10 to 5%. Flock elimination of footrot has been successful in flocks across the world through treatment of diseased sheep, culling all non-respondents and persistently lame sheep, targeted vaccination (including mono and bivalent vaccines) and regular footbathing of healthy sheep in periods of non-transmission until no further disease is detected, even in a period of disease transmission. This has been most successful when initiated when climatic conditions are regularly unfavourable to transmission of footrot and where the percentage of flocks with footrot is low and flock level biosecurity can be maintained to prevent re-introduction of footrot to a naïve flock. Both control and elimination strategies are successful to reduce the global burden of footrot. Success is dependent on choosing the correct strategy for the flock given climate, biosecurity and force of infection and commitment to the programme.