METERGOLINE FOR THE TREATMENT OF PSEUDOPR EGNANCY AND FOR THE INTERRUPTION OF LACTATION IN THE BITCH

Metergoline, a prolactin inhibitor, serotonin antagonist and dopamine agonist, was used to treat 179 pseudopregnant bitches: 1978/79 in 36 p atients in Bremen (A), in 68 bitches in Vienna (B) and 52 bitches in M unich (C), using a dose of 200 mu g/kg body weight (BW) b.i.d., and in 1993/94 in 23 patients in Hannover (D) with a dose of 100 mu g/kg BW b.i.d. Metergoline was found effective at both dose levels, treatment resulting in a significant acceleration of the return to normalcy rega rding mammary gland regression, cessation of mammary gland secretion a nd return to normal behavior. Bromocriptine (10 mu g/kg BW) was used i n study D (a blinded trial) as a positive control (n=17) and was found equally effective, while lactose as a negative control (n=10) showed the somewhat stower spontaneous resolutions of the clinical symptoms o f pseudopregnancy. Duration of treatment with metergoline was 6.9 days (5.7 to 8.4 days) and the treatment effect (significant reduction of symptoms or normalization) was 79.9 % (63.8 % to 100 %). Observations of side effects included vomiting in 15 % (30 % following use of bromo criptine) and severe disturbances of behaviour of central nervous orig in in 50 % of all bitches treated with metergoline. This caused cessat ion of treatment in 25.7 % of all patients. The higher dose in studies A to C may have contributed to these disturbances. Metergoline when u sed to interrupt lactation following sectio porro (cesarian section an d simultaneous ovariohysterectomy) was fully effective within 5.3 to 7 .8 days and with this population, behavioural disturbances were seen l ess often (8.3 %). It remains unclear if there is a dose of metergolin e which is clinically effective but free of these side effects.