Breeding is an enormous investment of time, money and emotional energy for most mare owners and breeders. Since the live foaling rate for mares is very low – around 50 percent, it is wise to assure that your mare is in good reproductive health before sending her to the breeding farm. This will maximize your chances for early conception and healthy pregnancy.
Before sending your mare to the farm, make sure that her weight is normal, she has been recently dewormed, and that she is current on her vaccinations, especially for influenza and rhinopneumonitis.
It is common for veterinarians to do a palpation (manual examination) of the mare’s internal genitalia in the Spring, before breeding. This examination will determine any abnormal size, shape or consistency of the uterus, cervix or ovaries. In addition, it may help time breeding more accurately. Your vet will clean stool out of the rectum, extending his/her arm into the rectum, and feel the uterus and ovaries through the rectal wall. If your mare objects to the examination, your vet may twitch or even sedate her. Proper restraint is vital not only for the safety of the veterinarian but also that of the mare – if she is not calm and still, the exam can cause a tear in the rectum, with serious consequences.
Inflammation and/or infection of the uterus is a common cause of infertility in the mare. There are three barriers against entry of bacteria into the uterus – the vulva, the vestibule (opening to the vagina), and the cervix. Any abnormality in one or more of these barriers allows bacteria or fungi to colonize the uterus – this condition is called endometritis. As mares age and have several foals, the vulva may stretch and relax to such an extent that stool from the overlying rectum will be aspirated in to the genital tract. These mares require a common, simple and inexpensive surgery known as a caslicks procedure. Some mares develop tears in the cervix post foaling that must be repaired. These can only be detected by an internal examination of the cervix, both by looking at it through a long tube speculum and by manual examination. A maiden mare should always have a speculum examination of her vagina prior to breeding, in order to detect and remove a persistent hymen, if present. Failure to remove the hymen may lead to breeding and/or foaling complications.