Foot Rot

Cattle: sudden lameness, then symmetrical swelling of the interdigital space and coronary band that spreads evenly around the hairline of both claws; the interdigital skin cracks open to reveal a foul-smelling necrotic core. Without early treatment infection reaches deeper structures, causing septic arthritis of the coffin joint or septic tenosynovitis. Sheep: lameness with lesions ranging from mild interdigital dermatitis to complete under-running and separation of the hoof horn.

In cattle, foot rot (interdigital phlegmon or necrobacillosis) is an acute infection of the interdigital skin and underlying tissue. Fusobacterium necrophorum is the organism most often isolated, working with other bacteria such as Porphyromonas levii and Prevotella species. Infection starts where interdigital skin is abraded by gravel, stubble or rough ground and kept constantly wet; the tissue swells, the skin splits to expose foul-smelling necrotic material, and neglected infection extends to the navicular bone, coffin joint, coffin bone and tendons. In sheep, footrot is a distinct disease caused by the anaerobe Dichelobacter nodosus; virulent strains, distinguished from benign ones by the AprV2 protease, progress from interdigital dermatitis to under-running of the hoof horn.

Cattle foot rot occurs at all ages and becomes more frequent in wet, humid conditions and where animals stand in wet areas or on sharp gravel, brush and stubble. In dairy herds overall incidence is probably below 5%, but in epidemic outbreaks up to 32% of the milking cows in a herd are affected. Ovine footrot spreads between sheep, and warm, moist conditions favour both transmission of D. nodosus and the appearance of lesions. Benign and virulent strains of D. nodosus circulate and are told apart by their protease genes. Ovine footrot has a large economic impact on production and, being painful, is considered a significant animal welfare problem.

In cattle: interdigital dermatitis, sole ulcers, sole abscesses and abrasions, infected corns, fractures, septic arthritis and tendon sheath infection; cleaning and examining the foot shows the symmetrical interdigital swelling and necrotic, foul-smelling skin fissure that mark foot rot. In sheep the major differentials are contagious ovine digital dermatitis, white line disease and foot abscesses.

Interdigital skin and subcutis, coronary band, hoof horn, coffin joint and bone, navicular bone, tendons and tendon sheaths

Cattle: prevent foot trauma from gravel, brush and stubble, limit time standing in wet areas, feed a balanced trace mineral programme with adequate zinc and iodine; a commercial foot rot vaccine is approved for cattle.

Cattle: early systemic antimicrobial treatment usually succeeds; delayed treatment can fail once infection reaches the coffin joint or tendon sheaths. Ovine footrot ranges from mild dermatitis to full under-running, depending on strain.