One Galloway bull and three German Holstein-Friesian cows aged between three and five years with complicated arthritis of the fetlock joint were treated by arthrotomy (on the bull and two of the cows) or by arthrodesis (on the other cow). Arthrotomy involved four vertical dorsolateral/dorsomedial and palmolateral/palmomedial incisions 5 cm long to give access to the joint cavities and allow fibrin, debris and necrotic tissue to be removed. Arthrodesis consisted of lateral and medial (abaxial) horizontal 5 cm incisions along the joint space. After debridement, the joint surfaces (cartilage and superficial bone tissue) of the metacarpus and first phalanx were completely abraded with a high-speed surgical drill. The interdigital region, palmar and dorsal tendons, vessels and nerves were conserved during both arthrotomy and arthrodesis, and the pouches were flushed during the surgery. The incisions were sutured and a casting tape was applied. Six weeks later, the cast was removed and a supporting bandage was applied. Each animal received 10 mg/kg ampicillin subcutaneously twice a day from one day before surgery until a mean (sd) of 23 (4) days after the arthrotomies and 36 days after the arthrodesis. After a recovery period of at least one year, all the animals could be used without restrictions.