Osteoporosis is a systemic bone disorder characterized by decreased bone density, which can weaken bone strength and increase the risk of fractures. Osteogenesis imperfecta (OI), one of the main causes of osteoporosis in children, results in fragile bones and multiple fractures. The present study documented the case of a dog with an undetermined osteoporotic disease managed with intramedullary rod fixation. A 3-month-old intact male Alaskan Malamute dog, weighing 11.6 kg, was presented with lameness in the left pelvic limb. Radiography revealed left pelvic and femoral fractures, and the cortex of the long bones was thin. On CT scanning, a significant decrease in trabecular bone mineral density (BMD) was observed compared with normal dogs. Hyperparathyroidism was ruled out on the basis of blood tests and ultrasonography. Histopathological examination of the fragmented bone revealed remodeling with no evidence of neoplasia. Genetic testing could not differentiate OI in the dog, therefore an undetermined osteoporotic disease was tentatively diagnosed. Fractures were managed using multiple intramedullary rods. Although the trabecular BMD further decreased and additional surgery was required due to the migration of inserted rod and additional fracture, body weight of the dog was increased from 11.6 kg to 28.6 kg during the follow-up. The clinical symptoms, including pain and lameness, improved. Taken together, rodding surgery might be a viable option for dogs with pathological fractures due to osteoporotic disease by distributing weight and preventing bending force.