Effects of bromocriptine and perphenazine on prolactin and progesterone concentrations in pregnant pony mares during late gestation

Abstract

Pregnant pony mares in Group A (n = 4) received i.m. injections at 07:00 and 17:00 h of 0.8 mg bromocriptine/kg body weight 0.75 per day beginning on Day 295 of gestation and continuing until parturition. Group B (n = 4) was treated similarly, but perphenazine was administered orally at 0.375 mg/kg body weight twice a day beginning on Day 305 of gestation and continuing until parturition. Mares in Group C (n = 3) received i.m. injections of saline. Mean plasma prolactin and progesterone concentrations were greater (P less than 0.05) for mares in Group C than in Groups A and B from 295 to 309 days of gestation. From 305 days of gestation, plasma prolactin and progesterone concentrations were greater (P less than 0.05) in Group B and C than in Group A mares. Progesterone and prolactin concentrations increased over this period for Group B and Group C mares, but remained constant in Group A mares. From 10 days pre partum through foaling, mares in Group A had lower progesterone (P less than 0.05) and prolactin (P less than 0.01) concentrations than Group B and C mares. All mares in Group A were agalactic at foaling, while all mares in Groups B and C had normal milk secretion. Gestation was longer (P less than 0.05) in Group A than in Group C mares. In Group A, 2 mares retained the placenta for greater than 3 h, 3 mares had dystocia and all 4 mares had thickened, haemorrhagic placentae.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromocriptine Treatment for Inappropriate Lactation in Mares: A Case Report

“…However, its dosage, efficacy, and side effects are not well defined in the mare [1,37]. There is no basic information on pharmacokinetics of bromocriptine in horses, and the use of oral formulation in this species has not been reported yet [34].…”

“…There is no basic information on pharmacokinetics of bromocriptine in horses, and the use of oral formulation in this species has not been reported yet [34]. The administration of bromocriptine at a dose of 0.08 mg/kg, b.i.d, intramuscularly, in ponies during the final third of gestation period caused a reduction in plasma levels of prolactin and progesterone and induced clinical signs similar to those observed in pregnant mares intoxicated by the fungus Acremonium coenophialum in fescue pastures [1,37].…”

Dinâmica hormonal durante o processo luteolítico nas espécies equina e bovina; com ênfase sobre o papel da prolactina

“…Em equinos, a maioria dos estudos envolvendo a PRL está relacionada à prenhez (AURICH et al, 1995;IRELAND et al, 1991), parto (WORTHY et al, 1986) e sazonalidade reprodutiva (KING et al, 2010b;GREGORY et al, 2000;HOFFMAN Jr;DEPEW, 1997). Os níveis da concentração de PRL são elevados no verão e baixos no inverno (THOMPSON et al, 1986).…”

“…Uma baixa dose de Bc (10 mg) reduz a concentração de PRL na estação ovulatória, mas não na anovulatória, quando as concentrações estão naturalmente baixas (BECKER; JOHNSON,1990). Em éguas em final de gestação, no momento em que a placenta é a fonte principal de P4, a concentração de P4 é reduzida pela Bc (IRELAND et al, 1991). Entretanto, aparentemente não foram realizados estudos sobre os efeitos da redução de concentração de PRL por Bc durante o ciclo estral em éguas.…”

“…In horses, the majority of the published studies on PRL are related to pregnancy (AURICH et al, 1995;IRELAND et al, 1991) parturition (WORTHY et al, 1986), and seasonality of reproduction (KING et al, 2010b;JOHNSON, 1986;GREGORY et al, 2000;EVANS et al, 1991;THOMPSON et al, 1986;HOFFMAN Jr;DEPEW, 1997). There is a rise in serum and pituitary PRL concentration in the summer, whereas concentrations are low in winter (THOMPSON et al, 1986).…”