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

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 = 75), adrenalectomy +/- AA (Group 2, n = 128), or neither treatment (Group 3, n = 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 days, 95% CI: 76-418 days) than in Group 2 (927 days, 95% CI: 587-1267 days; p < 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 = 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 = 0.02) and in Group 2 alone (HR 0.3; 95% CI 0.1-0.7; p = 0.01).

Conclusions And Clinical Importance: Dogs with PCC treated with adrenalectomy have longer survival compared to those managed with AA without adrenalectomy.