BACKGROUND: Disorders of the locomotor system in dogs, such as amputations or malformations, can be not only physically but also emotionally distressing. In this context, advances in medical and technological sciences offer tools and options with the aim of improving the quality of life of animals with locomotor problems. This case report aims to describe the custom development of a 3D exoprosthesis for a dog with an amputated hind limb. CASE PRESENTATION: A female dog, mixed breed, approximately 5 years old, was admitted to the Veterinary Clinic of the Centro Universitário de João Pessoa-Brazil, with locomotor problems due to low amputation of the left hind limb, without pain or sensitivity to touch on the amputated stump. Measurements of the amputated limb were collected to create a virtual model of the 3D exoprosthesis in a socket model. After simulations and tests, the prosthesis was materialized by 3D printing in collaboration with the Brazilian company 3D Medicine©, using polylactic acid (PLA) as the main material, an organic, lightweight, and resistant synthetic thermoplastic. The exoprosthesis was covered with protective material and fixed to the animal with a compressive bandage. Immediately after fixation, the animal demonstrated support of the limb on the prosthesis while standing, better distribution of body weight and relief of load on the contralateral limb. The increase in the time of use of the prosthesis was gradual and under supervision, after four weeks the dog did not present major difficulties in walking, running, and eating, in addition, no injuries to the amputated stump were observed. Veterinary physiotherapeutic follow-up was recommended. CONCLUSION: This case report describes the development of a 3D exoprosthesis for dogs as a cost-effective option to reduce the locomotor impacts of limb amputation and improve quality of life. Techniques using additive manufacturing and 3D technology have immense potential for medical application, especially in veterinary medicine due to the difference in anatomical and body structure between domestic and wild animals.