Voss K, Kull M, Hässig M, Montavon P. Katja Voss, Dr. med. vet. Diplom. ECVS, University Veterinary Teaching Hospital Sydney, 65 Parramatta Road, Camperdown NSW 2006, Australia, Phone: +61 2 9351 3437 , E-mail: k.voss@usyd.edu.au. VCOT 2009 22 5 398-405 Objectives: To retrospectively evaluate stabilisation of long-bone fractures in cats and small dogs using the Unilock system. Methods: Medical histories and radiographs of consecutive patients with long-bone fractures stabilised with the Unilock system were reviewed. Cases with follow-up radiographs taken at least four weeks postoperatively were included. Signalment of the patient, fracture localisation and type, primary fracture repair or revision surgery, single or double plating, and complications for each patient were noted. Additionally, implant size, number of screws, number of cortices engaged with screws, and number of empty holes across the fracture were evaluated in fractures where a single plate had been applied. Results: Eighteen humeral, 18 radial, 20 femoral, and 10 tibial fractures were treated. The Unilock system was used for primary repair in 44 fractures and for revision surgery in 22 fractures. Two plates were applied in 17 fractures, and a single plate was applied in 49 fractures. Follow-up radiographs were taken four to 109 weeks postoperatively. Complications were seen in 12 animals and 13 fractures (19.7%). Fixation failure occurred in seven fractures (10.6%). Cases with a single plate that suffered fixation failure had thinner screws in relation to bone diameter than cases with double plates, and more screws in a main fragment than those without fixation failure. Clinical significance: The Unilock system is a suitable implant for fracture fixation of long bones in cats and small dogs.