What is the role of GnRH agonists (e.g., deslorelin) in canine reproductive management?

• A. Used to stimulate ovulation in all dogs
• B. Used to suppress or synchronize estrus/ovulation; implants provide prolonged GnRH suppression
• C. Used to treat mammary tumors
• D. Used as a general analgesic

Answer: (B)

GnRH agonists manipulate the brain’s command of reproduction to either stop or time the reproductive cycle. They act on the pituitary to alter gonadotropin release ( LH and FSH ): with a GnRH agonist, you get an initial surge, then the receptors become desensitized and the pituitary shut downs, so gonadal hormone production falls and the animal stops cycling. In dogs, this is used to suppress estrus or delay puberty and to coordinate breeding by temporarily turning off estrous activity. The implant form, like deslorelin, releases the drug slowly for a prolonged period, giving long-lasting, reversible suppression of GnRH signaling without ongoing injections. This makes it a practical tool for controlling when ovaries ovulate or when a dog comes into heat, and it can be stopped as the implant wears off so normal function returns later. It’s not a method to stimulate ovulation, nor is it a general analgesic, and while hormone therapies can influence mammary tumor biology in some contexts, GnRH agonists are not a primary treatment for mammary tumors.