Foot rot is characterized by a sudden onset of lameness. The animals are very painful and will often only touch their toe to the ground. One or more limbs can be affected by foot rot, although it is usually one of the hind limbs. The skin and soft tissue between the toes become red and swollen, which causes the toes to spread apart. A swelling from the top of the hoof to the dewclaws or higher is often observed. Affected cattle will eat less because of decreased grazing time and fewer trips to the feed trough, or they may go off feed altogether. The skin between the toes will develop a crack where protruding dead or decaying tissue will be present. There is a foul odor. If the animal is not treated at this point, the infection may spread to the deeper structures, including bones, tendons, and joints. When this happens, it is considered a chronic condition, and is much harder or impossible to treat. The swelling will become more severe and may go up higher on the leg. Animals will often carry the leg at this point.
A condition named super foot rot has been a problem in some areas. Super foot rot is a strain of F. necroforum that is resistant to multiple antibiotics. Super foot rot will appear the same as regular foot rot in the early stages of the disease, but will progress rapidly and not respond to standard treatments. If a case of foot rot continues to worsen, even after treatment, a veterinarian should be consulted. While foot rot is a major cause of lameness, it should not be assumed that all lameness is due to foot rot. Conditions that can have similar clinical signs are fractures, sole abscesses and abrasions, fescue toxicity, and infected toes. To determine if it is foot rot, the foot must be examined. Only with foot rot will the skin and tissue between the toes be swollen and cracked with decaying tissue protruding.