A Multicenter, Retrospective Analysis of Long-Term Survival in 255 Dogs With Pheochromocytoma Treated With Alpha-Adrenoreceptor Antagonists or Surgery (2010-2021).

Abstract

BACKGROUND: The survival of dogs with pheochromocytoma (PCC) treated with adrenoreceptor antagonists has not been described or compared to surgically managed cases. HYPOTHESIS/OBJECTIVES: The objective of this study is to evaluate the survival of medically and surgically managed dogs with PCC and investigate factors associated with survival. ANIMALS: Two hundred fifty-five dogs with PCC, treated with alpha-adrenoreceptor antagonists (AA) without adrenalectomy (Group 1, n&#x2009;=&#x2009;75), adrenalectomy +/- AA (Group 2, n&#x2009;=&#x2009;128), or neither treatment (Group 3, n&#x2009;=&#x2009;52). METHODS: Retrospective, multicenter review of medical records. Median overall survival time (OST) for Groups 1 and 2 combined was calculated using Kaplan-Meier estimates, and then compared between Group 1 and Group 2 using Log-Rank testing. Cox proportional hazard analysis identified factors associated with survival in Groups 1 and 2 individually and combined. RESULTS: Median OST for all cases was 854 (95% CI: 572-1136) days. Median OST was lower in Group 1 (247&#x2009;days, 95% CI: 76-418&#x2009;days) than in Group 2 (927&#x2009;days, 95% CI: 587-1267&#x2009;days; p&#x2009;<&#x2009;0.001). In Group 2, 88/92 dogs (97.8%) that received presurgical AA treatment survived to discharge compared to 23/27 (85.2%) that did not receive AA pretreatment (p&#x2009;=&#x2009;0.03). Lack of clinical signs at presentation was associated with increased survival in both groups combined (HR 0.5; 95% CI 0.3-0.9; p&#x2009;=&#x2009;0.02) and in Group 2 alone (HR 0.3; 95% CI 0.1-0.7; p&#x2009;=&#x2009;0.01). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with PCC treated with adrenalectomy have longer survival compared to those managed with AA without adrenalectomy.