A case-control survey study of environmental risk factors for primary hypoadrenocorticism in dogs

Background: Primary hypoadrenocorticism in dogs is thought to be multifactorial with roles for both genetic and environmental factors. The contributions of environmental factors remain unexplored. Objective: Identify environmental and lifestyle exposures associated with primary hypoadrenocorticism in 2 dog breeds with high risk of developing the disease. Animals: Animals were not used in this study. Owners of Standard Poodles (STPDs) and Portuguese water dogs (POWDs) participated in a survey. Methods: Retrospective case-control study. Dog owners were invited to participate in an online survey through convenience sampling. Questions regarded the demographics, health histories, and indoor/outdoor environments in which their dogs live and play. Responses for dogs with primary hypoadrenocorticism were compared to those without the disease using univariate and multivariate logistic regression models. Results: Five thousand forty-seven responses (358 cases, 4689 controls) met initial inclusion criteria. Significant associations with modest effect size were found for community type, ingestion of canned food, and use of lawn fertilizer in some analysis models. Reproductive (spay/neuter) status exhibited the strongest association with high effect size across all models with adjusted odds ratio (OR) 2.5 (95% confidence interval [CI], 1.4-4.5; P =.003) for spayed females and 6.0 (95% CI, 2.6-13.9; P <.001) for neutered males. Conclusions and Clinical Importance: The large effect size for reproductive status reflects its high potential clinical relevance, whereas modest effect sizes for other environmental variables suggest lower potential clinical relevance. These findings are associations and do not necessarily imply causation. Before any actionable recommendations are warranted, additional evidence regarding biological mechanisms is needed.