Vulvitis (inflammation of the vulva) and vaginitis (inflammation of the vagina) can develop due to difficult labor, chronic contamination of the reproductive tract due to poor conformation, sexually transmitted diseases, or mating. Bruises and hematomas (a pool of blood under the surface of the skin) of the vagina may be found in mares following delivery of a foal. Severe inflammation of the vulva and vagina, including local tissue death, may also occur. The signs of severe inflammation can include an arched back, elevated tail, poor appetite, straining, swelling of the vulva, and a foul-smelling, watery discharge. Signs begin 1 to 4 days after birth and last for 2 to 4 weeks. In most cases, supportive care and treatment with antibiotics is sufficient.

Equine coital exanthema is caused by a viral infection and may lead to vaginitis and vulvitis. The disease causes discomfort, but does not decrease fertility (see Reproductive Disorders of Horses: Equine Coital Exanthema (Genital Horsepox, Equine Venereal Balanitis)).

Dourine is a sexually transmitted disease of horses caused by the protozoan parasite, Trypanosoma equiperdum. Early signs of the disease include swelling of the vagina and vulva. Dourine occurs primarily in the Mediterranean coast of Africa, the Middle East, southern Africa, and South America (see Blood Disorders of Horses: Dourine).

Last full review/revision July 2011 by Robert O. Gilbert, BVSc, MMedVet, DACT, MRCVS; Fabio Del Piero, DVM, DACVP, PhD; R. J. Erskine, DVM, PhD; Paul Nicoletti, DVM, MS; Jerome C. Nietfield, DVM, PhD, DACVP; Donald Peter, DVM, MS, DACT; Patricia L. Sertich, MS, VMD, DACT; Katrin Hinrichs, DVM, PhD, DACT; Brad E. Seguin, DVM, MS, PhD DACT