Lameness in sheep may be caused by a number of systemic diseases, some of which include navel/joint ill (Escherichia coli and Erysipelothrix), tetanus, white muscle disease, frostbite, chlamydial polyarthritis, rickets, enzootic ataxia (copper deficiency), mastitis, orchitis, nutritional osteodystrophies, selenium toxicosis, laminitis, dermatophilosis, bluetongue, ulcerative dermatosis, and in some countries, foot-and-mouth disease. Weakness, ataxia, and neurologic problems may be misinterpreted as lameness in diseases such as scrapie, listeriosis, and visna. Additional information on differential diagnosis, treatment, and prevention can be found under the specific topics (see Musculoskeletal System Introduction and Nervous System Introduction).
Lamenesses are often due to injuries. Broken legs are common in young lambs, which are frequently injured inadvertently by adults. Usually, these can be easily splinted and will heal within 3 wk. However, leaving the limb splinted and unobserved for too long may also lead to iatrogenic lameness. The general principles of treatment and prevention of these are the same as in other species.
Lameness can be caused by a group of infections specific to the feet. The most well known of these is contagious footrot, a mixed infection with Fusobacterium necrophorum and the obligate pathogen Dichelobacter nodosus. The skin between the claws is the primary site of invasion; it is predisposed to infection by breaks in the epidermis from injury or maceration from prolonged exposure to moisture. F necrophorum and Trueperella pyogenes induce a transient condition called ovine interdigital dermatitis or foot scald, which may lead to more serious problems.