AGGRESSIVE BEHAVIOR IN A BITCH AFTER DESLORELIN IMPLANT INSERTION

In male dogs, long-acting gonadotropin-releasing hormone (GnRH) analogs are widely accepted as an alternative to surgical castration but are also used to sup-press and induce estrus in bitches (off label). Behavioral changes reported in bitches in association with the use of long-acting GnRH analogs have included male-like behav-ior associated with triggered estrus, increased food intake, enlargement of mammary glands and milk production, pseudopregnancy, and urinary incontinence. In male dogs, intra-species and rarely inter-species aggression may occur during the flare-up effect. However, at the time of downregulation, this behavior should no longer occur if it is tes-tosterone dependent. An intact, three-year-old female cocker spaniel with Addison’s disease was admitted to our clinic for consultation on spaying options because of pseudopregnancies followed by mastitis, which had to be treated with antibiotics, after her heat cycles. The owners were hesitant about surgical sterilization and therefore, deslorelin implant was inserted. Approximately one month after implantation, owners observed the onset of aggressive behavior, including incessant barking, extreme irritability, and aggression toward other dogs and towards family members. The behavior problems started to escalate and the owners were not able to handle her anymore. After removal of the implant, the observed aggression ceased, and the bitch returned to normal behavior. Although aggressive behavior toward other dogs and sometimes even toward owners has been observed after neutering or insertion of a deslorelin implant, this is the first report of extremely aggressive behavior toward owners and other dogs in a female dog after insertion of a 4.7 mg deslorelin implant. Agresivno vedenje psice po vstavitvi implantata deslorelina Izvleček: V veterinarski praksi so dolgo delujoči analogi gonadotropin-sproščujočega hormona (GnRH) široko sprejeta alternativa kirurški kastraciji psov. Uporabljajo se tudi pri psicah bodisi za supresijo ali indukcijo estrusa, pri čemer gre za neoznačeno uporabo zdravila. Pri uporabi dolgo delujočih analogov GnRH so pri psicah opazili vedenjske spremembe, kot so moško obnašanje, povečan apetit, rast mlečnih žlez, laktacija, navidezna brejost in urinska inkontinenca. Pri pasjih samcih pa se lahko v začetnem obdobju, ko implantat spodbudi izločanje testosterona, pojavlja agresivnost do drugih psov ali redko drugih živali. Na naši kliniki smo obravnavali nesterilizirano, tri