[Possible side effects of hormonal castration in a dog]

A young, healthy male Labrador developed regurgitation, diarrhea, and decreased general condition after hormonal castration using a deslorelin implant (Suprelorin®) and concurrent cyproterone acetate injection. The gastrointestinal symptoms improved with symptomatic treatment, but lethargy persisted. The cause of the initial gastrointestinal symptoms is suspected to be impairment of the hypothalamic-pituitary-adrenal axis by the injected cyproterone acetate. Cyproterone acetate has a known glucocorticoid effect and inhibits the hypothalamic-pituitary-adrenal axis like other progestogens. Low-dose (0,1 mg/kg once daily) and high-dose (1 mg/kg once daily) prednisolone therapy led to a slight improvement in the general condition. Seven weeks after the cyproterone acetate injection, the dog was noticeably more active, but only after the surgical removal of the deslorelin implant did the owner considered the dog «back to his old self.« This suggests that the dog's reduced general condition was a side effect of the hormonal neutering. Twenty-one weeks after the deslorelin implant application and cyproterone acetate injection, and fourteen weeks after the last prednisolone administration, the adrenal glands responded normally in the ACTH stimulation test. One year later, the owner describes the dog as healthy without any gastrointestinal symptoms since then.