This condition is also known as vaginal fold prolapse or vaginal fold oedema. It may be seen in any breed, but is especially common in brachycephalic breeds as Boxers, Bulldogs and many Mastiff-like breeds (Boerboels). The strong breed predisposition suggests a hereditary nature. The condition occurs because of excessive swelling of the vaginal wall under the influence of oestrogen during early stages of heat. The condition is characterised by a pink, fleshy mass bulging from the floor or, less commonly, from the whole circumference of the vagina whilst in heat. Rarely, it may also occur during late pregnancy. Usually the condition recurs during subsequent heat cycles. The bitch does not necessarily have to show vaginal hyperplasia at her first heat. In most cases it will manifest before her third heat cycle. The mass may interfere with natural mating and artificial insemination is advised in these bitches. Different grades of the condition exist depending on how much of the vaginal wall actually protrudes from the vagina.
Whilst the debate about heritability is ongoing, some breeders elect to sterilize affected bitches whilst others wish to breed. It is the opinion of some breeders and veterinary specialists that even if conclusive evidence of heritability emerges, the benign nature of this condition does not warrant selection against it until more serious conditions have been addressed. For those wishing to breed the bitch naturally, surgical correction is possible. Once the wounds have healed, it may be very difficult if not impossible to check whether a bitch has undergone an operation for vaginal fold prolapse. Although very unlikely, a bitch which has been operated may still get vaginal fold prolapse at a next cycle (and then, usually in a much reduced form).