When examining the chronically infertile mare, it's important to remember that the uterus is not an organ suspended in space--it must be viewed as one part in a complex system. Anything affecting the animal, no matter how remote, can have an effect on the reproductive system, according to Michelle LeBlanc, DVM, Dipl. ACT, a practitioner with Rood & Riddle Equine Hospital. LeBlanc presented on diagnostics and case management of these mares at the Florida Association of Equine Practitioners (FAEP) Promoting Excellence Symposium, held Sept. 27-29, 2007, at the Atlantis resort on Paradise Island, the Bahamas.

Diagnosing these mares begins with a physical exam of the entire animal.

"Your physical exam and taking a good history will give you the answer about 60% of the time," LeBlanc said. The veterinarian should consider factors such as the mare's age, condition, and whether she's sound. If that checks out, then scrutinize the reproductive system more closely.

If she notes anything abnormal during the vaginal exam of the infertile mare, LeBlanc advocates running both cytology (examination of the cells) and cultures. In a recent study, LeBlanc and Tom Riddle, DVM, looked at the diagnostics used on 970 Thoroughbred mares in Central Kentucky. Of these mares, 55% of those with reduced fertility would have remained undiagnosed without cytology to catch inflammation, and 17% would have remained undiagnosed without culture to catch infections.

In another study, LeBlanc looked at the results of 401 small volume uterine flushes performed on 308 mares, correlating the clarity of the flushed fluid to laboratory findings. She found that cloudy fluid is highly indicative of the presence of bacteria, with Escherichia coli or beta Streptococcus being isolated most frequently. LeBlanc noted that practitioners using this technique increase their likelihood of finding bacteria in the uteri of chronically infertile mares by about twofold as compared to culture swab.

Another diagnostic tool LeBlanc uses is the endoscope to visually inspect the reproductive system. In one case she reviewed, a mare had no inflammatory cells on cytology and no bacteria isolated from a swab culture, but the endoscopic exam revealed that she had adhesions throughout her uterus. Without this diagnostic modality the cause of her infertility could have remained unanswered.

LeBlanc said she'll turn to the endoscope when she suspects adhesions, focal infections, foreign bodies, persistent endometrial cups (define), or when the cause for the persistent infertility is clear.

LeBlanc then presented case studies, asking the assembled practitioners for ideas on how they would proceed with the cases, and what treatment protocols and management plans they would institute once the cause of infertility was pinpointed.

LeBlanc was confronted with a difficult case involving a chronically infertile Saddlebred mare with a flaccid uterus, tiny ovaries, a cyst, and small adhesions between the cervical os (opening) and the vaginal wall--but these issues didn't fully explain her infertility. LeBlanc next turned to the endoscope, which revealed a bright red, inflamed endometrium. No organisms turned up as a result of a small volume flush. She next used DMSO (dimethyl sulfoxide, an anti-inflammatory and solvent) to eliminate the mucoid layer overlying the endometrium. A follow-up flush revealed Pseudomonas bacteria--which create biofilm (a protective layer that's a method of resistance for bacteria). Antibiotics cannot always penetrate biofilms, so the practitioner might need to use solvents such as DMSO before using antibiotics to eliminate an infection.

In another case, an owner brought a mare to LeBlanc because the mare lost her pregnancy after 45 days. A small mass was palpable on rectal examination. On ultrasonound examination the ultrasound beam could not penetrate the mass. LeBlanc used an endoscope to visualize the endometrium. The mare had a marble inserted in the past to keep her from cycling for competitive performance reasons, and it had fractured, leaving chunks of glass embedded in the tissue. LeBlanc noted that practitioners should be careful when they choose a marble for keeping mares out of estrus, as the marble might be retained for long periods of time and it could fracture. Practitioners should look for a ball with a smooth surface and only a few lines of color, if any, as fractures in the glass most frequently occur along these lines.

Take-Home Message

The diagnosis and treatment of chronically infertile mares is a complex process. Practitioners should utilize the available diagnostics, including cultures and cytology, along with endoscopy, to root out the myriad causes of this problem and increase the chances of these mares having a fertile future.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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