Oral administration of altrenogest for oestrus suppression in competition horses is believed to be widespread in some equestrian
disciplines, and can be administered continuously for several months during a competition season. To examine whether altrenogest
has any anabolic or other potential performance enhancing properties that may give a horse an unfair advantage, we examined the
effect of oral altrenogest (0.044 mg/kg), given daily for a period of eight weeks, on social hierarchy, activity budget, body-mass and
body condition score of 12 sedentary mares. It was concluded that prolonged oral administration of altrenogest at recommended
dose rates to sedentary mares had no effect on dominance hierarchies, body-mass or condition score.
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