Health: Product to aid conception rates

The Busol 10-10-10 Protocol

Busol is the only product licensed in the UK for the improvement of conception rates in mares by reduction of early embryonic death.

Many studies have that administering buserelin early in pregnancy improves pregnancy rates.

In a trial of 204 mares, 40mcg of buserelin administered 10-11 days after ovulation increased pregnancy rates, determined by ultrasound exam on Days 14-15, from 66.6% to 72.5% vs. untreated controls1 . This study also showed that pregnancy losses at days 28-30 (determined by ultrasound exam) were reduced from 7.4% to 4.1 % vs. untreated controls

In this same study two groups of 187 mares received either 40mcg of buserelin or placebo, administered 10-11 days after ovulation. Ultrasound determined pregnancy rates at 14-15 days after mating were 57.2% in treated mares vs. 53.5% in untreated controls.

Pregnancy losses at day 28-30 were 6.5% in treated mares vs. 12.0% in untreated controls.1 In a follow-up study to confirm these results, 2346 mares were examined over a 4-year period. Analysis of the results confirmed that administration of 20-40mcg buserelin 8 to 12 days (average 10 days) after service increased pregnancy rates by an average of 10%.

In a study of 250 warmblood mares, 40 mcg of buserelin was given 10 days after AI using fresh or fozen semen. The mean pregnancy rate in the treated group was 48.4% versus 36.4% in the untreated controls.5

The Busol 10-10-10 protocol:

Based on these studies a protocol of administering 10ml of Busol to mares, 10 days after ovulation, to increase conception rate by 10% is proposed. We hope this information is useful. If you have any further questions, please do not hesitate to call our Veterinary Team on 00353 (0) 1 841 7666 or email us at


 1. Pycock JF and Newcombe JR. (1996) The effect of the gonadotrophin-releasing hormone analog, buserelin, administered in diestrus, on pregnancy rates and pregnancy failure in mares. Theriogenology. 46: 1097-1101.

 2. Newcombe JR, Martinez TA, Peters AR. (2001) The effect of the gonadotropin-releaseing hormone analog, buserelin, on pregnancy rates in horse and pony mares. Theriogenology. 55: 1619 – 31.

 3. Newcombe, J.R., Peters, A.R. (2014) The buserelin enigma: How does treatment with this GnRH analogue decrease embryo mortality? Journal of Veterinary Science & Technology.

 4: 151. 4. HPRA. (2017) Publicly Available Assessment Report for a Veterinary Medicinal Product. Busol 0.004 mg/ml solution for injection for cattle, horses, rabbits.

 5. Unger C et al. (2002) Pregnancy rates in mares after application of gonadotropin releasing hormone analogue, Buserelin, in warmblood mares. Theriogenology. 58: 635-638.

An information service from Forte Healthcare Ltd., distributers of Busol. Busol contains buserelin. UK: POM-V. Further information available in the SPC  ( ) or from Forte Healthcare Ltd., Block 3, Unit 9, CityNorth Business Campus, Stamullen, Co. Meath, K32 D990, Ireland. Tel: 01292 800013. Email: