Evaluation of cabergoline and buserelin efficacy for oestrous induction in the bitch.

The purpose of this work was to compare two different protocols of oestrous induction, using either a dopamine agonist (cabergoline) or a GnRH agonist (buserelin) in anoestrus bitches. The clinical trial involved 22 Beagle bitches, randomly allotted to two treatment groups: group A (n = 12) was orally administered cabergoline (Galastop(R); Centralvet-Vetem, Milan, Italy; 5 microg/kg SID), until the onset of cytological oestrus or for a maximum of 30 days and group B (n = 10) was treated with buserelin acetate, (Suprefact(R); Aventis Pharma, Milan, Italy), administered subcutaneously t.i.d., at 1.5 microg/kg for 11 days and 0.75 microg/kg for the following 3 days. Blood samples were collected twice a week to measure progesterone and prolactin concentration. Both cabergoline and buserelin produced a significant early decline in prolactin concentration (p < 0.01), but the effect of cabergoline lasted longer. Progesterone concentration was significantly affected by buserelin administration, showing a significant increase (p < 0.01) from day 3 to day 6 of treatment. Cabergoline confirmed its effectiveness in inducing oestrus as 10 of 12 bitches responded to the treatment, were mated and whelped. On the contrary, oestrus was observed in only three of 10 buserelin-treated bitches and in two of them 7 and 13 days after the end of treatment. These same two bitches accepted mating and conceived. The results suggest that in a clinical setting, dopaminergic treatment is the treatment of choice as it yields more consistent results and involves a much easier administration protocol.