Lameness in Sheep

Lameness remains one of the most important health and welfare issues facing sheep producers. It can have significant adverse effects on the economic performance of the flock.

Footrot, the commonest cause of lameness in UK flocks, is the prime example, with control programmes being most effective if action is taken on a whole flock basis. The key thing to under-stand is that footrot can be controlled with a dedicated whole flock approach, and is not something that we simply have to live with.

The first step must be to diagnose the actual cause of lameness in affected sheep. Whilst footrot is the most common condition, there are other causes of lameness, including scald and Contagious Ovine Digital Dermatitis (CODD) for example, and it can be easy to confuse the symptoms. Farmers should consult the practice to make an accurate diagnosis based on the clinical examination of a significant number of sheep, because the treatments required may differ.

Effective Diagnosis

Scald can usually be controlled with footbathing, but CODD is more difficult to treat and so the objective must be to work us to keep this disease out of the flock. Footrot is a highly contagious condition that, if left uncontrolled, can have severe economic and welfare consequences.

The only way to break the footrot cycle is to undertake a WHOLE flock control programme. The ‘best practice’ control programme starts by vaccinating and footbathing all sheep, then splitting the flock into two groups: those sheep that are obviously infected and those which are not infected. This simplifies the treatment regime, reduces the disease challenge for uninfected sheep and helps identify those animals not responding to treatment for culling.

Infected sheep should be given an antibiotic injection and walked through a footbath every five days. After three footbath treatments, any sheep that have not responded should be considered for culling.

Uninfected sheep should be footbathed and moved onto clean grazing. If it is not practical to segregate uninfected and infected sheep, make sure all the animals are footbathed every five days.

Vaccination

Annual vaccination should be a central part of the programme for all sheep that face a footrot challenge, with additional booster doses being used to treat infected animals. Vaccination with Footvax provides effective treatment for infected sheep, as well as long-term protection. A single injection of the vaccine can be used to treat footrot because antibodies are produced against D. nodosus.

Sheep do not produce a natural antibody response to D. nodosus, which means they will never develop a natural immunity to footrot so will remain susceptible year after year. This is why vaccination is so important.

An initial 1ml injection will stimulate adequate antibody response to treat existing infections and prevent new ones for up to five months. But it is advisable to vaccinate again four to six weeks later for improved cure rates and longer on-going protection. Thereafter, an annual booster should be sufficient to keep footrot at a manageable level.

Footbathing and Foot Trimming

Footbathing and foot trimming are integral parts of overall foot care in UK flocks, and used in conjunction with vaccination will improve overall disease control, but they are not cures for footrot in isolation.

Foot trimming can be an important aid in the diagnosis of different lameness conditions, but should be carried out sparingly and must never
draw blood.

Excessive trimming is itself a common cause of lameness in sheep, and soft tissue damage can cause a toe granuloma (or ‘strawberry’). Footbathing applies a topical disinfectant that may not penetrate sufficiently into the infected hoof to control footrot, but it is usually effective in controlling scald in lambs.

Under any circumstances, it is important to ensure that footbath design is suitable to accommodate enough contact with the treatment solution, as appropriate for the chemical being used. Various solutions are used for footbathing, copper sulphate is probably the most effective and Kling-on Blue (http://www.kling-onblue.co.uk/) the product of choice.