Case Fi le: Mare Infert i l i ty

SIGNALMENT AND HISTORY• Jewell, 16-year-old American Quarter Horse mare

• Halter horse

• Dystocia (breech presentation) the previous year

• Subsequently bred over four estrous cycles with two different stallions

• No pregnancy detected

• Referred to the CSU Equine Reproduction Laboratory

INITIAL EXAMINATION• Very good overall health

• Ultrasound examination revealed normal ovaries and uterus

• Presence of corpus luteum on right ovary indicated that the mare was cycling

• No free fluid or endometrial cysts in uterus

• No abnormalities of perineal area

CONTACT INFOColorado State University

Veterinary Teaching Hospital

300 West Drake Road

Fort Collins, CO 80523-1620

Phone: (970) 297-5000

Fax: (970) 297-4100

csuvth.colostate.edu

Apri l 2011• Volume2Appl ied Research for Today’s Equine AthleteDiscovery

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This case study represents the collaborative work of the

Colorado State University Veterinary Teaching Hospital Equine Services and the Colorado State University Equine Reproduction Laboratory.

Ultrasound of the right ovary showing corpus luteum (arrow).

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Ultrasound of the uterus (arrow) above bladder.

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Ultrasound of uterus with fluid (arrow) after mating.

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INITIAL BREEDING PROGRAM• Mare was inseminated with cooled-transported

semen

• Spermatozoal motility was very good (86 percent total motility)

• Mare ovulated on schedule the day after insemination

• Inflammatory fluid was present in the uterine lumen the day after breeding

• Uterus was lavaged with lactated Ringer’s solution and the mare was administered oxytocin to evacuate the uterine fluid

• Uterus was free of fluid the day after treatment

PREGNANCY EXAMINATION• Ultrasound examination 14 days after ovulation

revealed that the mare was not pregnant

ADDITIONAL DIAGNOSTIC TESTS• Culture of a uterine swab yielded growth of

Streptococcus bacteria

• Cytologic examination of a uterine swab was normal (i.e., no white blood cells)

• Endometrial biopsy evaluation noted mild inflammatory changes (grade 1B)

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Photograph of bacterial culture plate with Streptococcus colonies.

Photograph of uterine cytology evaluation under microscope.

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Photograph of oviduct (arrow) on surface of the ovary.

Photo of PGE2 being applied to oviduct via a pipette.

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Photograph of oviduct (arrow) after application of PGE2 gel.

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Ultrasound photograph of 14-day pregnancy examination.

Ultrasound examination of 25-day pregnancy examination.

FOLLOW-UP TREATMENT• Uterus was lavaged with lactated Ringer’s solution

• Antibiotics were infused into the uterus for three consecutive days

• Recheck uterine culture revealed that the uterus was free of bacterial infection

ADDITIONAL BREEDING MANAGEMENT• Mare was bred over three additional estrous

cycles without a pregnancy

• Two different stallions were utilized

• Semen motility was very good, timing of insemination relative to ovulation was excellent

• No pregnancies were detected

NOVEL THERAPY• A laparoscopic surgery was performed to

apply prostaglandin E2 (PGE2) to the surface of each oviduct

• The objective of PGE2 therapy was to dilate the oviducts and allow for clearance of potential oviductal blockage

LAST BREEDING ATTEMPT• Mare was inseminated with cooled-transported

semen from one of the same stallions used previously

• Motility of spermatozoa was good

• Mare ovulated on schedule

PREGNANCY EXAMINATION• Ultrasound examination 14 days after ovulation

revealed that the mare was pregnant

• Subsequent ultrasound examinations were performed to monitor development of the embryo and fetus

• The mare was sent home and is due to foal this summer

At Colorado State University equine veterinary care is delivered through the collaboration of three nationally recognized equine service centers: (1) Colorado State University Veterinary Teaching Hospital Equine Service; (2) Colorado State University Equine Reproduction Laboratory; (3) Colorado State University Orthopaedic Research Center. Equine treatment capabilities at CSU are at the forefront of equine veterinary medicine through the shared expertise of these organizations.

RESOURCES• Colorado State University

Veterinary Teaching Hospital: csuvth.colostate.edu

• For more information contact Drs. Patrick McCue or Ryan Ferris in the Equine Reproduction Laboratory at (970) 491-8626 (www.cvmbs.colostate.edu/bms/erl/).

DISCUSSION POINTS• A majority of cases of mare infertility can

be directly attributed to mare reproductive abnormalities, semen issues, or breeding management factors.

• However, in some cases mares fail to become pregnant despite a normal reproductive evaluation, use of good quality semen from more than one stallion, and optimal reproductive management.

• Blockage of the oviduct with gelatinous-cellular masses may inhibit fertility by either prevention of sperm from reaching the site of fertilization or prevention of an embryo from reaching the uterus.

• PGE2 has been reported to dilate the oviduct and may clear the oviduct of blockage.

TAKE HOME MESSAGELaparoscopic application of PGE2 to the surface of the oviducts should be considered as a potential treatment for mare infertility once other causes, such as persistent mating induced endometritis, ovulation failure, poor semen quality, infectious endometritis, and poor breeding management have been ruled out.

Click on the image above to view a 42 second video clip of the PGE2 gel application procedure.