Ulnocarpal arthrodesis as a new treatment for ectrodactyly in a dog and a cat.

Case History: A 4-month-old male Shih Tzu dog (Case 1) and an 11-month-old female Devon Rex cat (Case 2) were referred to specialist veterinary hospitals for evaluation of right thoracic lameness and growth abnormality in the distal aspect of the forelimb.

Clinical Findings: Non-weight-bearing lameness and decreased range of motion were noted in the affected limbs of both cases. Case 1 had a plantigrade stance, and a cleft separation between the first and second digits extending upwards to the distal third of the antebrachium. There was no pain on palpation, and the affected limb was shorter than the contralateral. Radiographic examination revealed cleft separation between metacarpal bones I and II, and carpal bone fusion (I, II, III), and the distal radius ended freely and was attached to the first metacarpal bone.Case 2 had a small cleft medial to metacarpal III. The limb was consistently held in abduction and had marked carpal varus. The limb had never been used for weight bearing. Radiographic examination showed agenesis of metacarpal bone II and separation of metacarpals I and III. The radius and ulna were separated and the radial head did not articulate normally at the elbow, leading to marked elbow incongruity.

Diagnosis: Ectrodactyly in both cases.

Treatment And Outcome: Amputation of the radius followed by ulnocarpal arthrodesis were performed in both cases. Follow-up evaluations up to 1 year (Case 1) and 10 weeks (Case 2) after surgery indicated satisfactory arthrodesis fusion, owner satisfaction, and a good clinical outcome.

Clinical Relevance: Ectrodactyly is a rare congenital deformity of the forelimb with a heterogeneous character, requiring an individualised treatment plan. These are the first cases reported in the literature of ectrodactyly in small animals that were treated successfully with ulnocarpal arthrodesis. This case series therefore provides evidence in support of this treatment option for this heterogeneous congenital deformity.