Fatal pulmonary hemorrhage associated with vascular amyloid deposition in a cat

CASE SUMMARY: An adult female spayed Siamese-cross cat of unknown age was presented for bilateral hemorrhagic otorrhea. Nasopharyngeal polyps were diagnosed by CT and biopsy; bilateral ventral bulla osteotomies were performed. Episodic epistaxis, otic hemorrhage and hemoptysis with respiratory distress progressed over 18 months. Systolic blood pressure, complete blood count, plasma biochemistries, prothrombin time, partial thromboplastin time and coagulation factor 12, 9 and 8 activities were normal. Serial thoracic radiographs revealed patchy interstitial to alveolar patterns. Airway hemorrhage prevented diagnostic bronchoscopy. Respiratory hemorrhage was ultimately fatal. Amyloid deposition was identified in pulmonary vasculature, bronchial wall, lymphoid tissues, nasal-pharyngeal tissue and tympanic bullae based on microscopic examination and confirmed by Congo red staining with green birefringence under polarized light. RELEVANCE AND NOVEL INFORMATION: Amyloidosis should be considered as a differential diagnosis in cats with spontaneous hemorrhage of the respiratory or otic tracts. Although systemic amyloidosis is associated with a grave prognosis, this case suggests that prolonged survival is possible after the initial onset of signs in cats with pulmonary amyloidosis.