Chris R. Smith, DVM

It is that time of year again! The leaves have fallen off of the trees, Thanksgiving has come and gone, college football season is over and basketball has begun. These are all triggers in our minds that breeding season is right around the corner, and so we begin to make preparations to ensure a successful start. Most of us have our mares under lights by now, but we must not forget an invaluable tool to consider during this time of year, a good comprehensive breeding soundness exam performed by your veterinarian on all of the barren and maiden mares.

A comprehensive breeding soundness exam involves much more than making sure the mare has two normal size ovaries and a normal vaginal speculum exam. First, the external genitalia is examined for any abnormal findings or anatomic abnormalities that might lead to a problem. Conformation of the vulva and regions surrounding are evaluated to make sure there are no abnormalities that might predispose the uterus to contamination by fecal material. The plane in which the vulva lies should be fairly vertical. There should also be a good, competent seal intact between the vulva to prevent aspiration of air which could lead to ascending infections as well as urine pooling.

A rectal exam and ultrasound is usually performed next to evaluate the uterus, ovaries, and cervix. It is important to make sure there are two normal size ovaries present for the time of year in which the exam is performed. One would expect the ovaries to have follicular activity present if the exam is performed in the spring/summer or if the mare has been under lights for a reasonable period of time. The ovaries might be considerably smaller with little to no activity if the exam is performed in the winter. Ovarian tumors, cystic ovaries, and hematomas can lead to an enlarged ovary, and chromosomal defects can lead to ovaries which might barely be palpable.

Next, the uterus is palpated and scanned to evaluate its size and tone, as well as to examine the lumen for any abnormalities. External or serosal adhesions might be palpated per rectum if the mare has had a prior Caesarean section performed. Adhesions might also be seen in the lumen of the uterus, as well as tumors, cysts, pus, or persistent endometrial cups. The cervix is then palpated to try and determine the stage of the estrous cycle. Most abnormalities of the cervix are found on the next step of the breeding soundness exam which is the vaginal speculum examination. By inserting a tubular speculum, one can detect many abnormalities such as urine pooling, tears/lacerations to the vaginal walls, accumulation of pus, cervical tears and/or adhesions, or there might just be some inflammation of the tissues present.

The cervix as well as the dorsal vaginal wall should also be examined by digital palpation to rule out tears and/or adhesions, especially if the mare has a history of a difficult labor and delivery in her past. At this time procedures can be performed to look at the uterus on a microscopic level. A uterine culture, cytology, and biopsy are utilized to try and determine if the uterine environment is suitable for breeding and maintaining pregnancy.

To perform these procedures it is best for the cervix to be open and the mare in heat so there is less chance of contaminating the uterus. A guarded swab is usually used for the culture and a small brush is used for the cytology. Some veterinarians prefer to perform a low volume lavage for culture and cytology. By running a small volume of fluid into the uterus and retrieving the contents, many cells are obtained from the entire uterine environment and not just a focal area as compared to the swabs and brushes. Biopsies are typically used in problem mares and perhaps older mares to determine the amount of glandular distention, fibrosis, and inflammation that might be present within the uterine wall. This is an excellent prognostic indicator as to whether the mare can conceive and carry a foal to term. One might even culture the biopsy sample to determine if there is an active infection in the deeper tissues of the uterus. Bear in mind that this is also a small, focal, and often blind sample that is taken, and might not be representative of the entire uterus.

There are two other useful diagnostic tools that might be performed to further gain more valuable information in regards to a mare’s success as a broodmare. Endoscopic exams have become highly popular among veterinarians as a means of allowing direct visualization of the lumen of the uterus. A videoendoscope is inserted thru the cervix into the uterine lumen, and one can visualize the uterus by driving the scope throughout the entire cavity searching for abnormalities. Common problems such as tumors, cysts, foreign bodies, adhesions, or even just a small foci of infection can be diagnosed in this manner. One can ensure that the fallopian tubes are patent during this exam as well. Furthermore, a biopsy may be taken of a more specific region of concern versus a more conventional, blind approach. Endoscopy has proved to be an invaluable asset in equine reproduction particularly in problem mares where most common problems have been ruled out.

One other tool that has recently been introduced is the Strep Activation procedure. Often times mares get chronically infected throughout the breeding season and can be a real headache to the veterinarians as well as the owners/farm managers. These uterine infections are many times attributed to contamination by the stallion, inadequate defense mechanisms, or poor reproductive conformation. However, it has been shown that bacteria can often lie dormant in the deeper tissues of the uterine wall. These bacteria can periodically become active and migrate out of the wall into the uterine cavity allowing their detection with a positive uterine culture or cytology. They can be hard to treat due to their location and the inability of systemic antibiotics to penetrate well into these deeper tissues. This new procedure allows one to activate close to 100% of the dormant bacteria within the wall all at once to migrate into the uterine lumen where they can be effectively treated and destroyed. This procedure takes a chronic condition and turns it into an acute situation which is more likely to respond to our therapeutic treatment. The veterinarians at Hagyard have experienced a high degree of success with this new diagnostic and therapeutic tool that has recently become available.

Hopefully you now understand how and why your veterinarian utilizes these tools to provide a thorough breeding soundness exam. Expenses can quickly escalate throughout the breeding season, especially when the rate of cycles per pregnancy increase, therefore it is important to evaluate and diagnose problems before the season starts to minimize these costs and increase pregnancy rates. It won’t be long before the first foals hit the ground in 2013, and hopefully with some preparation and a little luck, it will be a good season for us all.