Footrot in Sheep

An infection which causes major changes to the hoof resulting in lameness and loss of production.

Symptoms of the Disease/Condition.

Footrot in sheep is a very complex disease. It is an infection which causes major changes to the hoof resulting in lameness and loss of production. It is a very painful condition and has the potential to become an animal welfare issue.

There are three factors that may interact with each other to have an impact on the disease:

1. The agent that causes the disease-anaerobic bacteria called Dichelobacter nodosus.
2. The hosts that carries the disease - sheep and goats
3. The environmental circumstances within or external to the host that cause or allow disease transmission - moisture and temperature.

D.nodosus can survive in the feet of sheep for a long time but not in the ground. They produce proteolytic enzymes that allow invasion of the hoof.

Sheep of all ages are susceptible and susceptibility increases with age. Merinos are recognised as more susceptible than most other breeds.

The national prevalence in NZ is low. The number of sheep getting infected can range from 2-20% in a flock in any one year depending on the weather and what management systems are in place for preventing spread of footrot.

The risk of footrot is greater when the grass is actively growing. Susceptibility to footrot is more likely to be a function of immunity than a function of foot shape or body conformation.

Sheep with healthy, dry feet will NOT get footrot.

Cost/Impact on Herd/Farm Revenue.

Amongst Merino farmers, footrot is cited as the second most important disease behind gastrointestinal parasitism.

Studies in Australia have shown footrot causes sheep to lose weight, produce less wool, and have lower lambing performance.

Sheep with footrot are more susceptible to flystrike, especially over the ribs and belly.

Lame sheep during an outbreak can have a very disruptive impact on the day to day running of the farm.

Footrot can have an indirect impact on footrot free properties by limiting options for trading sheep and ram purchase.

Management of footrot can be very expensive in terms of direct cost inputs and labour. In NZ it is estimated the annual expenditure for footrot control is worth $18-20 million dollars which did not include the financial losses from decreased production.

Management and Control.

Footrot is manageable.

The key to managing footrot is farmer attitude and understanding the bacteria, its stages of development and its diagnosis.

Well designed and maintained facilities and equipment are an essential part of footrot management.

There is a vaccine available- timing of administration is critical.