Records of 243 cases of non-accidental injury (NAI) in dogs, and 182 cases in cats, submitted by a sample of small animal practitioners in the UK, revealed a wide range of injuries. These included bruises, fractures, repetitive injuries, burns and scalds, stab and incised wounds, poisoning, asphyxiation and drowning (which showed remarkable similarities to NAI in children), as well as sexual abuse and injuries specifically caused by firearms. Traumatic skeletal injuries in the dogs were more commonly found in the anterior part of the skeleton, in comparison with those resulting from road traffic accidents. Young male dogs and young cats were particularly at risk of NAI. A moderately increased risk was identified in the Staffordshire bull terrier, cross-breed dogs and the domestic shorthaired cat, whereas the Labrador retriever showed a decreased risk. No single injury or group of injuries, when divorced from the circumstances surrounding a suspect case, could be considered to indicate, conclusively, NAI. Repetitive injuries, however, were highly suggestive of NAI.