А clinical case of non-union in a cat after open fracture repair by intramedullary ostheosynthesis of the radius was described. The patient was presented with non-weight bearing lameness, fistulas with purulent discharge, swelling and severe pain. During the surgical revision, after bone sequestrum removal, the bone defect was filled with cancellous and cortical bone autografts. Osteosynthesis with a modified external bone fixator, made of Duracryl® Plus - a rapidly self-curing metacrylate polymer - and 6 Kirschner wires passing perpendicularly through both radial cortices was performed. The post-operative period was smooth, and after 23 weeks the external fixator was removed. Radiography showed very good bone healing, with excellent clinical result. The use of the ulna as a donor bone was very convenient because it allowed collecting a cortical graft of larger size. The extremely light model of external bone fixator provided adequate strength of fixation elements and proved to be an efficient and not expensive technique for osteosynthesis in cat with non-union fractures of the distal radius and ulna.