ИСТИНА

The present invention pertains to veterinary medicine and can be used for inducing a stable retention state and a rest state in dogs (di-estrus and meta-estrus, respectively) as well as a rest state in cats (anestrus). This agent acts on the hypothalamus and the pituitary gland and contains as progestogen an efficient amount of a 3,17-dihydroxy-6-methylpregna-4,6-dien-20-one, or ethers thereof, of general formula (I) in which R is a keto group, an acyloxy group or an OH group containing from 1 to 6 carbon atoms, while R<1> is -OH- or an acyloxy group containing from 1 to 6 carbon atoms. This agent may further include a previously micronised natural or synthetic oestrogen as well as one or more progestogens of the same formula.