Clinical use of GnRH agonists in canine and feline species.

GnRH (gonadotrophin releasing hormone) is a key hormone of reproductive function in mammals; agonist forms have been largely developed, and data concerning their use in small animal reproduction are now abundant. GnRH agonists act by a two-step mechanism. First, their agonist properties on the pituitary will cause marked LH (luteinizing hormone) and FSH (follicle-stimulating hormone) secretion into the bloodstream, accompanied by an increase in the concentrations of sex steroid hormones. Then, in case of constant administration, GnRH agonists will lead to pituitary desensitization, and FSH and LH levels will collapse. These two effects have been widely documented, and these compounds have many potential benefits in a clinical context, capitalizing both on their stimulating and sterilizing effects.