Referred Vaginal Pain: Cause of Hypersensitivity and Performance Problems in Mares? A Clinical Case Study

Abstract 

In mares, pneumovagina develops because of perineal malconformation. This condition may aggravate to cause vaginitis, cervicitis, and endometritis. In animal models, visceral pain has been associated with genital infections causing hyperalgesia and allodynia in the affected organs. The pain from genital infections may be referred to dermal areas of the hindquarter.

The aim of the current clinical case study was to determine whether performance problems attributable to hypersensitivity in dermal areas of the hindquarter, a classic symptom of nymphomania in the mare, may be caused by visceral pain resulting from irritative processes in the reproductive organs. Vulvoplastic surgery (Caslick operation) is a well-known treatment of mares in which poor perineal conformation is the underlying factor of genital infections. The current study is based on clinical examinations and performance of mares with hypersensitivity in dermal areas of the hindquarters before and after Caslick operation.

Fourteen mares exhibiting performance problems such as kicking against the rider's legs, bolting, or refusing to move forward were selected for this study. Performance problems or stereotypic behavior were observed either permanently or intermittently during estrus. In 12 of 14 mares (86%), the performance problems were totally eliminated or diminished within 6 months after Caslick operation.

The clinically observed performance improvement in the treated mares supports the hypothesis that problems attributable to hypersensitivity in dermal areas of the hindquarters may be caused by irritative processes in the labia vulvae, vestibulum, and vagina of the mare.

Keywords: Perineal malconformation, Vaginitis, Referred pain, Hypersensitivity, Caslick operation