Jenny Hart If you asked me to choose…
Karen Phillips, BVSc, MANZCVS: CHB Vets, Waipukurau
This article was first published in the magazine of the Black and Coloured Sheep Breeders’ Association, in September 2018. It is reproduced here with permission.
Lameness in sheep can be particularly bad in some years. It is a significant issue as lameness is painful and causes loss of production. Lame sheep being transported is also an area that will be monitored more closely as our Animal Welfare Regulations are introduced.
Most lameness in sheep occurs in the foot and is due to interdigital dermatitis (also known as scald) and footrot. The development of these conditions is due to complex interactions between the animal, the environment and the bacteria. The most important factors are thought to be wet conditions (so wet feet and can occur with wet pasture) and mechanical trauma to the foot.
Ovine interdigital dermatitis is a lesser version of footrot and mainly affects the skin between the hooves. It is more common when the underfoot conditions are persistently wet and stocking rates are high. Any age animal can be affected and up to 90% of the flock may get the condition with many having it in all four feet. The disease can stay around for months, especially in high clover or lucerne pastures. When you examine an affected animal, the skin between the toes looks red, swollen and may have a white film across it. The smell is not normally as bad as footrot and the hooves don’t show any under-running (where the hoof wall has come away from the soft tissues). If ovine interdigital dermatitis is a problem in your flock, foot bathing at 2 to 4 week intervals will reduce the numbers affected. Zinc sulphate as a 10% solution is the most commonly used foot bath solution. For individual animals, a topical antibiotic spray can be used eg. oxytetracycline spray but be careful of wool staining with some products.
Footrot is much more severe but resistance to it is somewhat heritable so selection against it is feasible. Animals with footrot have under-running of the hoof and may be severely lame. There is a black foul-smelling discharge and the detached horn can be lifted off and cut away easily. The sheep often loses condition, and flystrike is common during the warmer months. Affected sheep are a major source of infection for other sheep so rapid attention is important. You can treat these sheep with injectable antibiotics – and in many cases a single injection, along with careful foot trimming, will be enough. Foot bathing and topical sprays also have a part in control and prevention
Sheep adopting the characteristic kneeling position of one with sore feet. Photo supplied by Karen Phillips.
If you are having problems with lame sheep, talk to your veterinarian and make a plan to treat and control these conditions