Treatment of individual sheep to cure the lesions of footrot is required as a first step towards control of the disease.
D. nodosus is present in superficial layers of the skin (epidermis) but may be protected from surface (topical) treatments by the overgrowth of keratin horn. This is a problem mainly in chronic forms of the disease, when paring of the hoof to remove excess horn may be needed before treatment. On the other hand, because D. nodosus is present in superficial layers of the skin, injectable treatments take time (hours, days) to reach the site via the bloodstream and diffusion.
The range of treatments available and their main advantages and disadvantages are:
- footbathing – zinc sulphate solution incorporating a surfactant; there is a residual effect lasting several days to a week; duration of treatment required for chemical penetration is generally one hour, which is difficult to achieve for large flocks; liquid waste disposal is a problem.
- parenteral (injection)
- antibiotics – a range of formulations are effective; there is no residual effect; antibiotic use in livestock is being discouraged globally because of the risk of development of antimicrobial resistance; to be effective, sheep must be kept on dry ground or on wooden slats in a shed overnight after treatment
- mono or bivalent vaccine – these can be used as a treatment; there is a residual protective effect lasting several months; requires an adequate diagnostic workup to identify serogroups present
All treatment options require a whole of flock approach. Following any of the treatments, all feet of all sheep must be inspected. Regardless of the type of treatment, a small proportion of sheep (~1%) will fail to respond to treatment. These sheep need to be identified and removed from the flock.
All options for treatment of sheep with footrot are labour intensive and expensive. They require a long-term commitment and considerable investment. Therefore, it is important to obtain an accurate diagnosis of virulent footrot. There is no economic benefit in treating benign footrot. However, there is a diagnostic grey zone with intermediate footrot, where there may be some economic losses and separately in some regions where producers do become concerned about mild, temporary, seasonal lameness, particularly in young sheep; this syndrome is a form of footrot of uncertain economic impact that requires detailed research (see pages on intermediate footrot).
The following quote is from 1985 but holds true today: “If decisions are to be made on whether or not expensive control programs on individual flocks are to be instituted, the most important criteria will be the clinical and economic impact of the disease on the flock under observation, not the in vitro characteristics of potentially unrepresentative isolates” (Egerton, 1986).
A diagnosis of footrot may entail notification to regulatory authorities, an enforceable undertaking not to trade sheep (equivalent to quarantine), and mandatory treatment and control.
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Important disclaimer: The advice contained on this website is of a general nature. Please consult your veterinarian or government district veterinarian, animal health or biosecurity officer for an accurate diagnosis if you suspect footrot, and for specific advice on the best course of action to prevent, control and eradicate footrot.