Endometrial disease
One of the most common causes of reproductive failure is the "problem mare".These mares have persistent infections of the uterus which keeps the mare from getting pregnant or maintaining the pregnancy to term. These mare have or are at risk of inflammatory changes in the uterus. The two main uterine defenses against bacteria infection are mechanical (myometrial contractions to clear cellular material and fluid from the uterus) and cellular immune responses (white blood cell, lymphocyte, infiltration and destruction of bacteria). Failure of the uterus to mechanically evacuate uterine contamination may be due to lack of myometrial contractions, cervical malfunction, and tract position in the mare. Failure of the immune system to mobilize lymphocytes or decreased efficiency of the lymphocytes to destroy bacteria may also be a factor in endometrial disease.
Before going further, examine the information on a normal uterine cellular structure and how it changes with inflamation (uterine cytology).
Contamination of the uterus with bacteria is inevitable at breeding, after parturition, and during vagina examinations. One of the predisposing cause of endometrial disease can be poor conformation of the vulva (reviewed in mare anatomy, vulva conformation) which leads to introduction of feces and air bourne organisms into the vagina and resulting vaginitis. The bacteria invade the uterus and cause an inflamation. Defective vulva conformation should be corrected with a Caslick's procedure.
Mares which cannot spontaneously eliminate bacteria from the uterus after infection fall into three categories and must be intensively managed to become and maintain pregnancy.
The three categories of the "problem mare" which will be covered in the next 3 pages are:
- Acute infectious endometritis
- Chronic uterine infections, often with scar tissue
- Persistent mating-induced endometritis
