Mandibular osteosarcoma in a nutria (Myocastor coypus)

Area of Science:

• Veterinary Pathology
• Comparative Oncology
• Rodent Medicine

Background:

• Nutria (Myocastor coypus) are large, herbivorous rodents with limited reported spontaneous diseases.
• Osteosarcoma is a primary malignant bone tumor typically affecting long bones in dogs, but rarely reported in other species.
• Endocardiosis is a degenerative disease affecting heart valves, commonly seen in aging canines.

Observation:

• A four-year-old male nutria presented with acute lethargy, anorexia, and a facial swelling.
• Clinical examination revealed a loose mandibular molar with purulent discharge, indicative of a dental and potential bone infection.
• Radiographic imaging demonstrated a rapidly progressing, lytic, and proliferative bony lesion in the mandible.

Findings:

• Necropsy confirmed an invasive osteosarcoma of the right mandible, invading the dental arcade and likely causing secondary osteomyelitis.
• Histopathology confirmed the diagnosis of osteosarcoma, a rare finding in nutria.
• Incidental findings included endocardiosis of the tricuspid valve with right ventricular remodeling.

Implications:

• This case highlights osteosarcoma as a potential neoplastic disease in nutria, necessitating further investigation into its prevalence and risk factors.
• The concurrent finding of endocardiosis suggests potential shared or coincidental pathologies in this species.
• This report contributes valuable data to the comparative oncology and pathology of exotic and wild mammals.