Ovine foot rot was first reported in 1869. It is an infectious, contagious disease of sheep that causes severe lameness and economic loss from decreased flock production. In a Virginia survey, approximately 21 percent of the producers considered foot rot to be a serious health problem in their flocks. With current understanding of the disease, and aided by drugs and vaccines, control and elimination of the disease should be the goal of all sheep producers.
Ovine foot rot is caused by an interaction of two anaerobic (without oxygen), Gram (-) bacteria, Bacteroides nodosus (formerly Fusiformis nodosus) and Fusobacterium necrophorum (formerly Sphaerophorus necrophorus). Fusobacterium necrophorum is a normal inhabitant of the ruminant digestive tract and in wet weather may interact with another bacteria, Corynebacterium pyogenes, to produce foot scald, an infection of the skin between the toes.
Lameness is usually the major sign of an infected animal, although sheep with an early infection may not exhibit lameness. The area between the toes first becomes moist and reddened. Then the infection invades the sole of the hoof, undermining and causing separation of the horny tissues.
The bacteria that causes foot rot, Bacteriodes nodosus, is spread from infected sheep to the ground, manure, bedding, etc., where it is then picked up by noninfected sheep.
It is always easier and less expensive to prevent foot rot than to treat it after it has become established. To remain disease free, there are five management principles that will help keep foot rot from being introduced into a clean flock.
The control of ovine foot rot is based on several management practices that decrease predisposing factors, and on the treatment and immunization of infected and susceptible sheep. The best results are obtained when several of the following methods are combined.
Using combinations of these procedures, foot rot can be eradicated. Eradication is difficult and requires commitment but is well worth the effort. In a comparison of treatments from recent studies (Table 1), it is apparent that eradication is possible using combinations of these treatment programs. It is also apparent from the following studies that no single treatment is effective. It must be a combination of the ones that best fit the facilities, management, and financial limitations of the flock owner/manager.