The Mare Breeding Soundness Examination: Part II

In Part One I talked about the importance of a good history and planning for a successful pregnancy that a breeding soundness examination (BSE) can augment you chances of a live foal. Now we'll review some other information. The physical examination should not be overlooked. Unrelated (to the reproductive tract) physical signs may have a direct influence on a mare's breeding soundness. It is well known that poor ...In Part One I talked about the importance of a good history and planning for a successful pregnancy that a breeding soundness examination (BSE) can augment you chances of a live foal. Now we'll review some other information. The physical examination should not be overlooked. Unrelated (to the reproductive tract) physical signs may have a direct influence on a mare's breeding soundness. It is well known that poor ...

Story originally posted by: Michael Lowder, DVM, MS

In Part One I talked about the importance of a good history and planning for a successful pregnancy that a breeding soundness examination (BSE) can augment you chances of a live foal. Now we’ll review some other information.

The physical examination should not be overlooked. Unrelated (to the reproductive tract) physical signs may have a direct influence on a mare’s breeding soundness. It is well known that poor nutrition influences the mare’s reproductive ability, but other clinical factors such as laminitis and pelvic injuries may make a mare reluctant to stand for breeding or unfit to carry a full-term pregnancy.

Once the general examination has been performed, the veterinarian can focus upon the reproductive organs. The mammary glands will be palpated for evidence of injury, mastitis, abscessation and neoplasia. The vulva will be examined for conformation, tone, apposition of the vulva lips, and abnormal discharge. Scars and puckers on the external genitalia and signs of past drainage present on the tail may provide clues to the condition of the internal organs.

We all know that as we age, things begin to sag. In mares, relaxation of muscles in the perineal area (the area surrounding the anus and vulva) can result in poor genital conformation. Normal muscle tension in this area provides for vertical alignment of the anus and vulva, but aged and malnourished mares may sag inward, forming a shelf on which feces and contaminates may collect. A sunken vagina also increases the likelihood of "wind-sucking" (drawing of air into the vagina) and urine pooling, which further predispose the mare to infection.

The rectal exam is a necessary, albeit uncomfortable, procedure that must be employed to assess your mare’s fertility. Luckily, the mare’s reproductive tract lies directly below the rectum. By carefully palpating the reproductive tract through the wall of the rectum, your veterinarian can detect pregnancy, injury, and scarring of the uterus, cervix, and ovaries. Because the equine rectum is easily torn, veterinarians should only perform rectal palpations.

Examination of the vagina is facilitated by the use of a speculum. Preparation for this step involves wrapping the tail and a thorough cleansing and rinsing of the vulva and perineal area. Once the area has been sufficiently disinfected and dried, a sterile speculum is introduced. With the aid of a light, the veterinarian can visualize and evaluate the cervix and walls of the vagina. Tumors, lacerations and scarring, inflammation and pooling of fluid can be observed at this time. Because the cervix is instrumental in preventing uterine infection and maintaining pregnancy, its visualization is perhaps one of the most important aspects of the BSE. Cervical infections and tears (from previous deliveries) can lead to adhesion formation and improper closure of the cervix. Although minor adhesions can be corrected, normal cervical function may not be attainable if severe adhesions have formed.

If the rectal or vaginal examination indicates problems with the reproductive tract, other procedures may be necessary for diagnosis and treatment. Culturing is an extremely valuable diagnostic tool that is used when an infection is suspected. Additionally, some breeding farms may insist that outside mares are cultured before they are serviced. Culturing is the process of growing organisms obtained from the uterus or cervix on a special nutrient gel. The organisms are then identified, and if harmful bacteria are found, antibiotic sensitivity tests are performed to determine the most effective treatment. Cultures are often taken during estrus, as the cervix is open and relaxed at this time and the increased estrogen levels in the blood increases uterine resistance to contaminates.

A biopsy is a procedure in which tissue samples are taken from the endometrium of the uterus for microscopic examination. Because endometrial degeneration and scarring are common causes of abortion and infertility, this tool is especially valuable in the diagnosis in mares that are barren, cycle irregularly, or have a history of abortion. There is a high correlation between pathologic changes in the endometrium and the ability to maintain a foal to term. Endometrial incompatibility may not be detected through palpation, specululum examination, and culture, and a biopsy will provide information that otherwise would not be available.

The use of an ultrasound has become quite popular and is another diagnostic tool that may be used during a breeding soundness exam. Ultrasound examination was first utilized in the 1980’s, and has greatly enhanced our knowledge of reproductive physiology, dynamics, and pathology. It can be used to diagnose uterine disease, ovarian irregularities (e.g. tumors, abscesses), and pregnancy as early as 10 days after ovulation (most vets, including myselft, wait until about day 15)! High-frequency sound waves are produced within the ultrasound’s transducer (wand), which pass through tissue and are reflected back. The reflected waves are converted to electrical impulses, which are then displayed on a screen. As tissues have different densities (e.g. fat, bone, muscle, and fluid have different densities), the area viewed can be interpreted and abnormalities noted.

In some cases, an endoscopic examination may be required. An endoscope is an instrument that is passed through the cervix and allows the viewer to visualize the internal structures of the uterus. This instrument can allow one to examine the uterus for any abnormalities (recall that the speculum allows the observation of the vagina and cervix), and its use is usually regulated to universities and research facilities due to their cost and special handling requirements.

I hope all this information has given you some insight into the importance of having a BSE done on your mare and please don’t wait until the breeding season do it. Have you mare check in the late fall and thus if there is a problem, eg, infection, there will be time to get it cleared up.