Vaginal prolapse is the protrusion of edematous vaginal tissue into and through the opening of the vulva occurring during the pro-oestrus and oestrus stages of the sexual cycle. True vaginal prolapse may occur near parturition, as the concentration of serum progesterone declines and the concentration of serum oestrogen increases. In a bitch, true vaginal prolapse is a very rare condition. This case report describes an 18-month-old crossbreed bitch, weighing 40 kg presented with type III vaginal prolapse. The patient had developed vaginal prolapse after receiving oestrogen in order to oestrus induction. Subsequent to unsuccessful attempts for repositioning, ovariohysterectomy (OHE), circumferential excision of the prolapsed tissue and finally vulvoplasty were performed. There was no evidence of recurrence of the prolapse during 30 days after surgery. This case report describes type III vaginal prolapse as an unusual side effect of oestrus induction hormonal therapy in the bitch.