Successful Management of Recurrent Hemoptysis, Polycythemia and Respiratory Distress in a Dog

A male castrated Shih Tzu was evaluated for recurrent nocturnal episodes of acute respiratory distress accompanied by hemoptysis and transient erythrocytosis. The dog was clinically normal between episodes, but each nighttime event was severe and prompted repeated emergency visits. During each emergency presentation, thoracic radiographs revealed severe diffuse interstitial-to-alveolar pulmonary infiltrates, and packed cell volume showed marked but reversible increases. A stepwise diagnostic evaluation, including serial indirect blood pressure measurement, coagulation assessment, echocardiography, and bronchoscopy with bronchoalveolar lavage, progressively excluded typical infectious, cardiac, structural, and coagulopathic causes of hemoptysis and acute respiratory distress. Given the stereotyped pattern of near-acute crises with diffuse pulmonary infiltrates and hemoptysis, mechanisms analogous to noncardiogenic pulmonary edema or exercise-induced pulmonary hemorrhage were considered. Therapeutic trials with sildenafil and furosemide failed to prevent further nocturnal recurrences. Considering concurrent transient PCV surges and the proposed role of catecholamine-driven splenic contraction as a rapidly mobilizable erythrocyte reservoir, a sympathetically mediated process was suspected, and α1-adrenergic blockade with prazosin was initiated. Following prazosin therapy, sustained clinical remission was achieved, with no further emergency episodes over a 17.5-month follow-up period. The response may have reflected multiple pharmacological effects of prazosin, including attenuation of sympathetically mediated splenic α1-adrenergic activity, systemic vasodilation, and reduction in venous return. This unique case suggests that dysregulation of the sympathetic nervous system may have contributed to the recurrent hemoptysis and acute respiratory distress and highlights adrenergic modulation as a potential therapeutic consideration in similar cases.