Extended daylight in the spring signals the start of the equine breeding season. Sunlight stimulates the release of hormones that influence ovarian activity. Before breeding mares, it is crucial to conduct a comprehensive reproductive evaluation.
A complete breeding soundness examination includes an overview of the overall health of the mare, a physical evaluation of the external genitalia and mammary glands and a combination of tran-rectal palpation and ultrasound of the uterus and ovaries. Additionally, diagnostic testing to thoroughly assess a mare’s breeding potential is an important consideration as well. Part of this assessment is determining the mare’s risk to endometritis, an inflammation of the uterine lining that is a common threat to equine fertility.
The Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL, offers three options for assessing a mare’s risk to endometritis:
- Endometrial culture
- Endometrial cytology test
- Endometrial biopsy
“I recommend cytology and culture no matter what,” Semira Mancill, DVM, DACT, veterinary diagnostician said. “Although not every mare needs a biopsy, each of these diagnostics are important to the pre-breeding evaluation.”
Diagnostic options to assess a mare’s breeding soundness
Each time a mare is mated or inseminated, she is at risk for pathogenic bacteria or fungal organisms invading the reproductive tract. If the contaminants remain, she could develop endometritis.
An endometrial culture begins with a swab sample of cells gathered trans-cervically from the lining of the uterus. TVMDL’s bacteriology section places the cells on plates and evaluates growth that may indicate the presence of infectious organisms. Growth may occur within 24 to 48 hours; however, yeast and other fungal growth can take up to 2 weeks..
A culture can reveal which microorganisms are within the tissue. Results may show bacteria, fungi or both; however, endometritis caused by fungi occurs less than bacterial infections. For example, a bacterium that commonly causes endometritis in mares is Streptococcus equi subspecies zooepidemicus. TVMDL offers antimicrobial susceptibility testing to rule out which antimicrobial agent is most effective to treat the infection.
An endometrial cytology consists of an examination of uterine cells under a microscope. TVMDL’s clinical pathologists evaluate the samples for abnormalities such as microbial pathogens and inflammatory cells.
“Culture and cytology are important tools in reproductive diagnostics because they are reliable methods to obtain evidence of an immune response in the endometrium and to identify any pathogenic organisms and their antimicrobial sensitivity,” Mancill said.
“When combined, the results are more powerful than when only one or the other test is performed.”
For an endometrial biopsy, a small amount of uterine tissue is taken from the mare. The specimens are then examined under the microscope for an assessment of inflammatory cells and pathology within the endometrium.
“A biopsy would be an additional option to culture and cytology.” Mancill said. “The biopsy will tell you what is going on inside the endometrial tissue. Biopsies are relatively easy to obtain and can provide a wealth of information.”
Maximizing success
An endometrial culture, cytology, and biopsy provide valuable results that can be used to measure breeding soundness in mares; however, these tests are only three pieces of the big picture. Above all, communication between veterinarians and their clients is important, especially during the breeding season.
“My biggest suggestion is to have good communication with your veterinarian and plan ahead,” Mancill said. “It’s good to have a plan laid out so that you may have the highest chance of meeting the goal.”
For more information about equine reproductive diagnostic options at TVMDL, visit tvmdl.tamu.edu or call the College Station lab at 888-646-5623.
