Etiology and Pathogenesis
In heavy beef breeds, the condition is thought to result from stretching of the insertions of the distal interphalangeal ligament. The claws splay, and the interdigital skin is stretched. When not involved in weight bearing, the skin folds outward and subcutaneous scar tissue develops. In these cases, a mass tends to develop in the axis of the interdigital space. The mass may become so large that it touches the ground and may become necrotic. There may be a heritable disposition in some breeds such as Herefords.
Corns are reported frequently in dairy cows when their feet are continually exposed to slurry, chronic irritation, or have interdigital dermatitis. Organization of areas of irritated skin on one side or other of the dorsal commisure accounts for development of corns in dairy cows.
Interdigital hyperplasia affects forelimbs. Lameness results more often than not. As the lesion becomes larger, its surface may become excoriated, sore, and infected.
In simple cases, treatment may be unnecessary. For surgical removal, the animal should be sedated, and dorsal and flexor regional nerve blocks administered (see Distal Digital Anesthesia for Diagnostic and Surgical Procedures in Cattle). Surgery can be performed with the animal standing or in lateral recumbency. After preparation of the surgical site, a tourniquet is applied and the claws separated manually or with retractors. The mass is removed, leaving as much of the interdigital skin as possible. If any fat protrudes when the claws are pressed together, it should be removed. Care must be taken to avoid cutting deep structures such as the distal interphalangeal ligament. After surgery, the wound should be dressed with an antibiotic powder and the claws bandaged closely together. Some field reports suggest considerable success with wiring the toe together. Movement of the wound or separation of the claws must be avoided until ~10 days after surgery. Cryosurgery is also an option.
Last full review/revision September 2015 by Paul R. Greenough, FRCVS