Multiple Cartilaginous Exostoses In A Pediatric Dog

Background: Multiple cartilaginous exostosis (MCE) is a rare neoplastic disease in dogs that is characterized by the presence of osteochondromas in multiple bones. MCE is a disorder of development during growth and maturation, the real etiology of which has yet to be elucidated, but is believed to have a genetic basis. Usually affected animals have a history of a palpable mass on the bone surface, causing anatomical deformities and compression of adjacent structures. Since MCE is a rare neoplastic disease in dogs it may be difficult to recognize in the clinic. The aim of this study was to report a case of MCE in a pediatric dog.Case: A female 4-month-old Rottweiler dog with a history of bone neoformation on the left hind limb, anorexia, weight loss, and difficulty walking received clinical care. The disease had its initial onset 2 months prior. At physical examination, the animal showed paresis of the hind limbs and a bony tumor on the lateral part of the left tibia. A complete blood cell count and serum biochemical profile were obtained. The only abnormality diagnosed was hyperproteinemia due to hyperglobulinemia. Other diagnostic tests were not authorized and the animal was euthanized. At the necropsy, an intrathoracic neoformation was observed from the sixth to the eighth rib on the right antimer. Some tumors were also observed on the fourth lumbar vertebra and between the first and the second sacral vertebra, and a left tibial tumor, which had been observed at physical examination. The sagittal section of the spine revealed the presence of extradural compression of the spinal cord due to vertebral proliferations with compression of the nerve roots. All of the proliferations had macroscopic similarities, being firm, sessile, irregular, and with complete adherence to deep planes. Tumor samples were submitted to histopathological analysis and the tissue morphology was compatible with osteochondroma. Based on the clinical, necroscopical, and histopathological findings, a diagnosis of MCE was established.Discussion: In MCE, animals less than one year of age are the most frequently affected, as was observed in the case reported. Clinical signs in MCE usually result from poor bone and cartilaginous anatomical formations and from compression of adjacent tissue structures. In the described patient, the proliferations located in the vertebrae and tibia and the consequent compression of nerve roots and nerves caused the neurological deficits. Unlike in canines, the etiology of MCE in humans is already well established and it is classified as an autosomal dominant genetic disorder. The diagnosis is usually obtained through the association of clinical examination with radiographic and histopathological findings. However, in the animal studied, since it was not possible to perform radiographs, confirmation was obtained only after performing histopathological examination of the neoformations, which is considered the standard for the diagnosis of MCE. Although it corresponds to a benign neoplastic process affecting dogs during their growth stage, it may significantly decrease the animal’s quality of life. In this situation, the prognosis of MCE is considered to be reserved to bad, and animals are often referred for euthanasia, as occurred in the animal under discussion, due to the progression of neurological dysfunction. Early recognition of MCE in routine pet hospital practice is of fundamental importance in order to properly institute treatment and monitoring.