Polyostotic lymphoma in a 7‐month‐old puppy ( <i>Canis familiaris</i> )

Abstract A 7‐month‐old, male, entire labrador retriever was presented for evaluation of the sudden onset of clinical signs of progressive lethargy and decreased proprioception reported by the referring veterinarian. Upon physical and neurological examination, the patient exhibited reluctance to walk, a squatting posture, pain on palpation of the long bones, and an absent to diminished menace response. Radiographs revealed poorly marginated, large osteolytic lesions involving multiple long bones. Ultrasound‐guided fine‐needle aspirates were obtained from multiple bone lesions. Cytological evaluation of the aspirates indicated large cell lymphoma. The pet was euthanised due to the poor prognosis and severe clinical signs. At postmortem examination, large cell lymphoma was also identified in the kidneys, the axillary lymph nodes, cranial mediastinal lymph nodes and bone marrow, indicating Stage V lymphoma. T‐cell lymphoma was confirmed via CD3 immunohistochemistry staining.