Radiation therapy (RT) for the management of canine appendicular osteosarcoma (OSA) can be described as either palliative-or curative intent. Palliative RT uses coarsely fractionated external beam RT or radiopharmaceuticals to provide relief of pain and lameness associated with OSA while resulting in minimal, if any, radiation-induced acute adverse effects. Limb amputation and chemotherapy are considered (together) the standard of care for curative-intent treatment of canine appendicular OSA. When limb amputation is not possible, RT can be used for limb sparing and is supplemented with chemotherapy for presumed micrometastatic disease. Fractionated tumour irradiation with curative intent appears to be ineffective and local disease control can more likely be achieved when stereotactic radiosurgery or intra-operative extracorporeal irradiation is combined with strict case selection and adjunctive chemotherapy. The availability of limb-sparing RT is limited by experience and availability of specialised equipment. When planned and administered appropriately, radiation-associated adverse effects are often mild and self-limiting. 16 A. Coomer et al.

HAUS placement was an effective method for the treatment of persistent USMI in most dogs and provided good clinical results based on owner assessment. The technique was associated with few complications and allowed successful long-term control of urinary incontinence without the need for medical management.

OBJECTIVE To characterize the processes involved in and outcomes achieved with custom-designed patient-specific implants to provide functional replacement of skeletal structures in dogs with tumors of the mandible, radius, or tibia. DESIGN Prospective case series. ANIMALS 6 dogs with mandibular tumors, 5 with tumors of the distal aspect of the radius, and 1 with a tumor in the distal aspect of the tibia treated from June 2013 to September 2016 at 3 referral centers. PROCEDURES After tumor staging, implants were designed from patients' CT scans by means of various computer-aided design applications and printed by means of selective laser melting in titanium-6 aluminum-4 vanadium alloy. A cutting jig was created in thermoplastic to ensure each osteotomy was performed as planned. Following ostectomy, the implant was secured into the defect with screws of appropriate size and length. RESULTS Initial return to normal clinical function was good to excellent for 11 of the 12 dogs. However, major complications resulted in revision of the implant or amputation of the limb in 5 dogs, and at least 3 of these complications were considered a consequence of faulty implant design or manufacturing. Infection developed in 2 dogs and was successfully treated in 1 dog. The longest-surviving dog maintained good limb function for 2 years. CONCLUSIONS AND CLINICAL RELEVANCE This is the largest reported series of dogs managed with customized 3-D-printed titanium implants. The 3-D printing allowed complex and patient-specific 3-D geometries to be fabricated, enabling function-sparing treatment of bone cancer affecting multiple anatomic sites.

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