Most horsemen don’t ride or compete on a pregnant mare, but with many mares it’s not difficult to combine careers—and even has some advantages. Still, some extra caution is in order for mares who will be ridden, especially if competing.

For Elizabeth Callahan, DVM, who breeds, trains and shows event horses in Maryland, her greatest concern regarding competing a pregnant mare is not the riding but the exposure to diseases.

“During the first 60 days of pregnancy, it is not recommended to vaccinate with West Nile virus vaccine. Hopefully your competition mare was already vaccinated before she became pregnant,” she said. “She may come into contact with diseases since you are taking her all over the place to various shows.”

Two diseases in particular—rhinopneumonitis and equine viral arteritis—could be devastating with a pregnant mare, especially if you bring her home after a show and put her out with other mares. “Both can present in a respiratory form. Your mare could be at a show in a stall next to a horse that has a clear nasal discharge and doesn’t look sick at all. You might not expect a problem. But then your mare comes home and may abort,” said Callahan.

If she’s turned out with other pregnant mares, this may create an abortion storm. “It’s very important with a pregnant mare to limit contact with other horses. If you can show from your trailer and not share water buckets, feed buckets, etc., this is safest. Some people think their mare is safe in a stall, but she may put her head over the Dutch door and sniff noses with the horse next door. And some stalls have big gaps in the walls between horses.”

Additionally, you don’t know the health status of the horse that was in that stall before your mare.

“Vaccination for rhinopneumonitis does not give 100 percent protection but helps, so if you are competing a pregnant mare you need a little more regular schedule than what is usually recommended for pregnant mares that stay home,” said Callahan. “In Kentucky, some of those mares are vaccinated at two, four, six, eight and 10 months instead of the three, five, seven and nine that most of us think of. If you are competing a pregnant mare, use a vaccine approved for prevention of abortion (some rhino vaccines are not) and up the vaccination schedule, just to be on the safe side,” she said.

If you are breeding to an EVA-positive stallion, the mare must be vaccinated before she’s exposed to him. “She then has to be isolated for 21 days after she’s bred. If your mare has been vaccinated for EVA, you are safe—regarding risk for picking it up at a show. But most people don’t think about having their mare vaccinated because most of the stallions we breed to are EVA negative. I don’t recommend vaccinating every sport horse mare for EVA because this means isolating them afterward, and it may be impossible to isolate your mare from other pregnant mares. This is a disease we don’t often think about. Since it can also present just as a respiratory illness, it can be devastating to your pregnant mare,” said Callahan.

How Much Riding Is OK?

Once the mare is bred and safely in foal, you can compete her with basically no change in diet or management up to about the sixth or seventh month of pregnancy, depending on your mare.

“There are some mares, especially maiden mares, that don’t develop much belly. Those mares may easily compete up to seven months. Some mares have very little abdominal development and could probably be ridden up until the day they foal; they look great and you would hardly know they are pregnant,” said Callahan.

But a mare that’s had a foal or two already may show her pregnancy much quicker. “She may get to the point at six months that saddle fit is an issue; the girth tends to sit too far forward and the saddle may slip forward due to the large belly,” said Callahan. “Some mares develop an ungainliness that changes their gait a little, and they are more awkward—especially when jumping. Some mares at six months have more balance issues and waddle as they move.”

After six or seven months’ gestation, Callahan said jumping is probably out. “And the size of the mare’s abdomen—[which may cause] problems getting your saddle to fit properly—may limit some of your competition. Mares can safely be ridden until they deliver, as long as the rider is careful,” said Callahan.

Most people who ride pregnant mares do so with young mares that will be put back into competition after weaning the foal—and those mares usually don’t have much abdominal enlargement.

“Many Europeans like to get two or three foals from a mare to see what she will produce,” said Kim Meier Morani, an eventer and breeder in eastern Maryland. “If she’s not a good producer, she can go right to work and become a show horse by age 5. They may start training at age 3 while she’s carrying the first foal, then turn her out for a while; she can be producing a foal as she grows up. Some people like to have a few foals from a mare by the time she’s 5 or 6 instead of waiting until she’s 15 (at the end of her show career). If she becomes a successful show horse, you already have babies from her.”

Extra Precautions

Callahan cautioned that some sports, such as racing, endurance riding or some types of eventing, which require an extreme amount of energy production, will produce a lot of body heat, and that may be risky for pregnant mares.

“One thing we want to avoid for the fetus is a high body temperature. If a mare’s temperature gets up to 104 or 105 degrees, which some competition horses do, this may be detrimental to the fetus. Avoid getting a pregnant mare to the point where she is overheated or exhausted,” she said.

A pregnant mare produces more body heat, requires more water, and if you are in a hot, humid environment she may not be able to cool herself as efficiently as a non-pregnant mare. This may keep her body temperature elevated too long and raise the fetus’ body temperature too high. Most hunters, jumpers, trail riding or dressage horses are not going to generate that much body heat.

“Working a pregnant mare to the point of exhaustion or overheating is actually more critical than how far into the pregnancy you keep riding her,” said Callahan.

The times to be most careful with a pregnant mare are during early pregnancy and late pregnancy. Danny Robertshaw, a hunter/jumper trainer in South Carolina, said that his veterinarian, Cindie Prestage, DVM of Camden, advised that during the first 60 days, loss of pregnancy due to stress—which can include transport to a show—is not uncommon.

“Once the mare is well along in pregnancy, it’s not so risky,” said Robertshaw. “It also depends on the mare. If climbing into the trailer is an every day affair and she is at ease with it, this is not as much stress as for the mare that’s nervous about traveling.”

The final third of pregnancy is also a risky time, when the weight of the fetus might cause a uterine torsion. A torsion (twist in the cervix and support structures if the uterus flips over) can occur if the fetus is heavy and the mare is carrying it very low, especially if she’s jumping. The best time to train or compete is between months 2 and 6, Robertshaw said.

“Light exercise is actually beneficial to the mare but should still be done with caution. If it’s a young mare you’re probably just continuing her training and doing light work. When I was young I had a mare I had no idea was pregnant and couldn’t figure out why she didn’t lose her grass belly by the end of summer. I rode her right up until the week before she foaled! I’ve had people tell me that if a mare is kept in exercise it keeps them tighter and fitter, but I don’t advocate continuing to ride until she foals,” said Robertshaw.

In terms of feeding, most pregnant mares in the first seven to eight months need nothing in addition to their normal rations.

“Pregnancy doesn’t need a lot of calories,” said Callahan. “The mare may need more energy to maintain good body condition while working but not because she’s pregnant.”

During late gestation, Callahan recommends ration balancers—the protein-vitamin-mineral concentrates without a lot of carbohydrates. “These are excellent for mares that are easy keepers,” she said. “We’re supplementing the fetus with the protein, vitamins and minerals that it needs, without overfeeding the mare and getting her obese.

“Making sure the mare’s ration is balanced and sufficient is important, whether or not you are riding her,” she added. “Even if the mare is an easy keeper and looks fine on grass, she still may not be getting the proper level of certain elements.”

Bonuses Of Working

One of the advantages to competing a pregnant mare is that it eliminates the inconvenience of having the mare coming into heat. “It eliminates the fuss of having to use Regumate or putting marbles in the uterus or any other things people do to keep mares out of heat. The pregnant mare is not cycling so there are no problems,” said Callahan.

Robertshaw believes it’s healthy to keep a pregnant mare somewhat fit. “And if you are doing something with her every day, riding her, you have more hands-on contact. You can read her better and really tell if she’s doing well with the pregnancy or if there are changes taking place. You have a daily relationship with her, and things won’t slip by you as easily. If she’s just turned out or coming in once a day for feeding, you may look at her, but you don’t really know what’s going on with her like when you are riding her every day,” he said.

OSA Remembered won the East Coast Regional Hunter Futurity at the Middleburg Classic (Va.) for Robertshaw while she was pregnant. She was later sold to Andrea Guzinski of Cedarhill Farm in North Carolina.

“This filly was always a delight,” said Robertshaw. “The very first time she went around a course she seemed to know what to do; work for her was very stress free. We started her in June and did the futurity in September, and she foaled the next March or April.”

He believes that deciding whether or not to ride a pregnant mare depends in part on how well you know the mare. “If you are going to add the stress of training and competing, you need to know the animal and be able to make that judgement wisely,” he said.

Guzinski breeds almost all her young mares at 3 years. “At that stage of their life and training they are not doing heavy work so this is a good time to breed them,” she said. “I continue working them just as I would any 3-year-old, which means I’m riding them three or four times a week and they are learning how to jump. They are going to small shows, getting used to being off the farm. I’m not really showing them so much as just exposing them to all the things they’ll experience at a show.”

She rides them lightly until about 2 or 3 months before they foal and also gives them a little time off after foaling. Then she may ride them again, depending on the weather. “I don’t want a hot, sweaty mare,” she said. “Usually we ride the mare wherever she and the foal are turned out—and the foal is running around as we ride—just to get the mare fit again as soon as possible. You just have to make sure the mare is properly cooled out before the foal nurses.”

Guzinski usually breeds the mare again as a 4-year-old and gets one more foal out of her at age 5. “I may be doing more training and showing during her 4-year-old year, but it’s mostly to give her experience. By the time I wean that foal the mare has had two very light years of competition and two beautiful foals and is ready to start an athletic career. Typically that’s when I stop breeding her and get her ready for her first year greens when she’s 6,” she said. “By then her knees are completely closed, and she’s physically mature and mentally more ready for serious competition.”

This program works so nicely that Guzinski prefers to raise fillies rather than colts. “When a colt is 3 years old I still have to go slowly with him, but he’s not able to do double duty; he’s not producing anything else during those light riding years! The fillies are much more productive.”

Riding The Mare With Foal At Side

As a child, Kim Meier Morani helped her mother with their riding camp in New Hampshire, where the pregnant mares might have a short time off after foaling. But when a foal was about a month old they started leaving it in the stall and taking the mare out for a 45-minute lesson, putting her back in the stall afterward.

“The mares and foals got used to it; there was always a buddy in the barn somewhere and the foal knew he wasn’t alone,” said Morani.

She had two mares that she continued to compete during pregnancy and while raising the foal. “I knew this could be done because a girl I knew competed all over New England [at training level] on more than one occasion with a broodmare. Her parents held or led the 2- or 3-month-old foal while she did her phases, letting it nurse periodically. The foals were cooperative, and the mare didn’t care and was perfectly happy doing this.”

So when Morani bred her mare, she rode her for four months while she was pregnant, during her training year, then let her have the winter off. “She foaled in May, and I started riding her again after the foal was a month old, taking the mare out of the stall for longer and longer periods. In August I started taking her away for the whole day, going to the fall events, and we’d be gone about 10 hours at a time. By then the foal was 4 months old and eating solid food and not missing mom too much,” said Morani.

“By mid afternoon at the show the mare would be squirting milk. She might have sticky hind legs when I did the stadium jumping and might waddle a bit because of her full udder. But she was a sweet, gamey mare and actually enjoyed her day away from the kid. With many mares it is quite feasible to continue to compete on them, up to training level, before and after foaling—if you have a handler to bring the foal along and keep track of it while you show or can time it so you’re not away from home for more than 10 hours.”