Evaluation of epidemiological and clinical findings of canine hyperadrenocorticism in Iran

Hyperadrenocorticism (HAC), also known as Cushing's syndrome, is caused by chronic exposure to excessive glucocorticoids. The objective of this study was to determine the epidemiological and clinical (especially ophthalmic) findings of dogs with HAC to increase recognition of suspicious cases in clinical routines. This study was examined on thirty dogs from Tehran, Mazandaran, and Guilan provinces between April 2021 and May 2022. The dogs included in the current study, who all had confirmed Hyperadrenocorticism, were selected based on the clinical findings suggestive Cushing disease as well as positive low-dose dexamethasone-suppression test. Then, general information, clinical signs, and ophthalmic factors were examined and recorded. The data were analyzed using the Chi-square test, Fisher's exact test, McNemar test, independent samples t-test, one-way ANOVA and LSD post hoc test. The mean age for the dogs with HAC was 9.7 years. The risk of HAC was also higher in neutered than intact dogs and also in terrier breed than other ones. Furthermore, significant differences were statistically observed concerning ophthalmic evaluations, including eye lesions, palpebral reflex, ophthalmic structural disorders, conjunctival, sclera, lens, retina, iris, and optic nerve involvement. However, gender, breed, common clinical manifestations, behavioural status, PLR test, menace test, dazzle test, cotton test, and corneal involvement did not show significant differences statistically. It was concluded that indoor and gonadectomized dogs had higher frequency in the studied population. We conducted epidemiological and clinical study of Cushing's disease in dogs in Iran, and for the first time, we examined the eye factors associated with this syndrome. These results support a better understanding of the canine hyperadrenocorticism in Iran. According to this study, the studied population resembles the profile described in European and North American epidemiologic studies, and the clinical picture of the HAC dog appears to be similar worldwide.