We Love Mares
By Bryant Craig, D.V.M., Merck Animal Health Equine Technical Services Veterinarian

American Quarter Horse Association (AQHA) Hall of Famer Corona Chick was a small brown mare who proved it didn't take a big horse to win a race. During her career in the early 1990s, she won 18 races, took second 15 times and placed third twice – earning nearly $600,000 in lifetime earnings. But the track wasn't where she made her mark in the history books and it was not where she made a lasting impression on my veterinary career either.

After retiring from her racing career, Corona Chick went on to carry 16 foals to term. Of these 16 foals, 14 made it to the racetrack earning more than $3.5 million collectively. Although most of her foals were winners, her biggest claim to fame was when she produced legendary AQHA Hall of Fame stallion Corona Cartel.

Prior to working for Merck Animal Health, I was the veterinarian at Lazy E Ranch where I had the privilege of seeing many of Corona Chick's offspring come through the yearling sales, at the racetrack and eventually in the breeding shed. Caring for Corona Cartel during his career as a breeding stallion is one of the highlights of my veterinary career. The beauty of specializing in reproduction is that I often got to witness life come full circle, which is a truly rewarding experience.

Although Corona Chick was probably the mare I admired most, she was not the only one to fuel my passion for the breeding industry and instill my deep respect for a good mare.

Trust the Original

Whether I was caring for a broodmare or a performance mare, estrus suppression was one of the most common requests I had from my mare-owning clients. Long before I worked for Merck Animal Health, I trusted Regu-Mate® (altrenogest) to safely and effectively suppress estrus in the mares under my care. Regu-Mate was the first FDA-approved estrus suppression product on the market and more than 50 million doses have been sold since its launch more than 30 years ago.

Glenn Blodgett, D.V.M., longtime resident veterinarian with the 6666 Ranch, American Association of Equine Practitioners Distinguished Life Member, AQHA former president and Hall of Famer, was one of the first veterinarians to begin using Regu-Mate in the early 1980s.

“From the time the product was launched to present day, Regu-Mate has been backed with data that made me feel comfortable using it in the mares under my care,” Dr. Blodgett says. “In my experience, Regu-Mate has been a dependable and trustworthy product for a variety of different uses.”

Managing the Performance or Broodmare

For the performance mare, Regu-Mate can be used to eliminate unpredictable behavior due to the mare's natural estrous cycle. Regu-Mate suppresses estrus within three days for 95 percent of mares and can be given safely for 15 consecutive days. Mares will return to estrus within four to five days after treatment is discontinued – and after your important show is over.

“Most of our mare-owning clients use Regu-Mate during their show season and some even claim their mares are un-showable without Regu-Mate to suppress their estrus behavior,” says David Scofield, D.V.M., Dipl. ACT, who works for Select Breeders Services and specializes in mare and stallion infertility and high-risk pregnancies. “In fact, I had one high-level retired show jumper who would rub her tail on stall walls so badly when she was in estrus she would hurt herself; we managed her with Regu-Mate other than the time frame we needed to pull embryos from her and when she was naturally in winter diestrus.”

Even in mares who require Regu-Mate on a consistent basis, there are no long-term effects on her reproductive health and it should not affect her ability to carry a foal or be eligible for embryo transfer during or after her performance career.

“We have used Regu-Mate in our performance mares during their show careers and then moved them into our broodmare herd with good results,” says Dr. Blodgett, who cares for 500 to 600 mares each year.

And performance mares aren't the only athletes who have changed today's breeding protocol. With many high-level breeding stallions being performance horses themselves, semen might not be available while your mare is ovulating. Regu-Mate can be given to suppress your mare's estrous cycle until semen is available. The use of Regu-Mate can be discontinued four to five days prior to the arrival of shipped semen and the mare will be ovulating in time for artificial insemination.

Additionally, Regu-Mate can be used to help suppress the first estrous cycle of the season. This first transitional cycle is often erratic and might not even include ovulation. By suppressing transitional estrus, you allow the mare to have her first official cycle earlier in the year.

“Whether we are using it for transitional mares, estrus synchronization or in the performance mare, the product has just been reliable and that is important to me,” Dr. Blodgett says. “I put the health of the horses in my care at the top of my priority list and I don't want to be in doubt of whether an estrus suppression product is going to work or not. That is why I have stayed with Regu-Mate for 30-plus years.”

Thank You, Mares!

“By far, the best moments of my year are watching maiden mares make the transition at foaling to being a new mom,” Dr. Scofield says. “They have no idea what has just occurred during foaling, but the hormonal cascade and act of parturition programs a mare to know exactly what to do. That exact moment when a maiden knickers to her new foal is why I love mares. They have never read any books, or had any friends tell them what to do, but they know that their foal is there and they are meant to care for it.”

Veterinarians are certainly not the only horsemen who can tip their hats to a mare that inspired them. Anyone who has earned the heart and respect of a good mare knows there is no loyalty truer. Today and every day, please give your mare a pat on the neck from the team at Merck Animal Health. Whether she is a ranch mare, racehorse, hunter or broodmare, she is special to you and that makes her special to us.

For more information on estrus suppression or Regu-Mate, talk to your veterinarian or visit Merck-Animal-Health-Equine.com.

Regu-Mate® is contraindicated for use in mares having a previous or current history of uterine inflammation. Pregnant women, or women who suspect they are pregnant, should not handle Regu-Mate®. For complete safety information please read label.

About the author

Bryant Craig, D.V.M., of Piedmont, Okla., received his doctorate of veterinary medicine from Oklahoma State University. He joined the Merck Animal Health equine veterinary technical services team in 2013. Prior to joining Merck Animal Health, Dr. Craig owned and operated a private equine veterinary practice in Oklahoma before joining the Lazy E Ranch in Guthrie as resident veterinarian in 2005. At the Lazy E, he oversaw the ranch's reproductive and yearling sales prep services and cared for some of the Quarter Horse racing industry's premier stallions.

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