When a horse is pregnant, is she at significant risk for lameness?

According to Dr. Sarah Sampson, a clinical instructor for equine surgery and orthopedic sports from Washington State University, any horse that is pregnant can become lame, but pregnancy alone is not a single factor for becoming lame. These horses can accidentally step on a nail, injure themselves in the pasture the same way any other horse would.

But most pregnant horses ( brood mares), or those that are used for breeding, since they were once performance horses that retired or got injured. Often, these mares may already have conditions, such as tendonitis, osteoarthritis, suspensory ligament injurier, or navicular syndrome, before they were even bred. These problems can worsen as the mares gain weight all throughout their pregnancy. The weight gain that comes with the pregnancy makes it all the more difficult on the joints, ligaments, and tendons, and owners will also find it difficult to manage the preexisting conditions.

Most of the time, brood mares are not managed in the same way during their pregnancy. For instance, there are owners who decide to stop shoeing the mare when she’s pregnant. Some of those mares with preexisting lameness should be kept in shoes and should continuously take their medications, although adjustment in the dose may be necessary all throughout the pregnancy.

It is important to have an evaluation for breeding soundness before they are bred regardless of their past medical history, says the doctor. This assessment includes examination of the reproductive tract to make sure that the mare is perfectly healthy to sustain pregnancy. Physical examination is also necessary to make sure that the mare is in ideal shape both systemically and orthopedically.

If the mare is not sound enough to sustain pregnancy, an embryo transfer procedure can be an option for some horse breeds. The procedure involves the transfer of the fertilized egg of the desired mare to the uterus of a healthy mare to allow pregnancy to reach term. This option is also available for owners who want a foal but also need their mares to remain in competition.

If pregnant horses are ridden, they can become more vulnerable to injuries due increased weight, and riding will become more physically difficult for them. If the mare is inactive before she was bred, then training should not start when she’s already in foal.