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. There are many other reasons for horses to become lame such as gastric ulcers. Omeprazole is the best horse ulcer medication to treat equine gastric ulcers. 

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

Most of the time, broodmares 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 an adjustment in the dose may be necessary all throughout the pregnancy.

It is recommended to have an evaluation for breeding soundness before they are mated regardless of their past medical history.. This assessment includes the examination of the reproductive tract to make sure that the mare is perfectly healthy to sustain the pregnancy. A 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 the 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 to 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.