Ask the Vet: Preparing Your Mare for Breeding Season

Answered by, Madison Seamans, DVM, MS, Cornerstone Equine Medical Service, Wilder, Idaho Courtesy of AAEP

Question: I was told it is not wise to breed an Appaloosa to an Appaloosa. What issues would this present, and what are the chances of a normal Appaloosa coat? Please advise.

Answer:The question of breeding horses opens the proverbial “can of worms” for a lot people.  One concern for breeding Appaloosa horses is due to a serious eye problem known as equine recurrent uveitis (ERU). Though the exact cause is not clear, there have been twelve genetic markers reported in horses with ERU. These are not limited to Appaloosas, and the test is not yet commercially available–and that ‘s the bad news. Thankfully, there are tests for other genetic flaws that can help us select our breeding stock, regardless of registration. (See the Appaloosa horse club website for a list of their favorites) 

Without testing, it may be impossible to know if a given horse has genetic flaws, which may be passed on to future generations. To make things even more complicated, recent research demonstrates the passage of some orthopedic and metabolic diseases not related to genetics, but transmitted directly from the mare!  With this in mind, we should be very careful in our reproductive choices, regardless of breed. Do not breed horses carrying diseases that can be identified by genetic testing. Do not breed horses with metabolic or orthopedic diseases (Equine metabolic syndrome, insulin resistance,  OCD or any lameness NOT caused by traumatic injury). The only way to remove undesirable traits from any breed or line of horses is to stop reproducing affected individuals. Thankfully, the Appaloosa Horse Club  allows “outside” blood. The policy stated in their website: “Pedigreed Appaloosas must have at least one ApHC-registered parent (sire or dam) classified as Regular (#). The other parent may be registered with the ApHC, or an ApHC-Approved Breed Association: American Quarter Horse Association (AQHA), Jockey Club (Thoroughbred), or Arabian Horse Association (AHA or WAHO)”.  This is a very wise policy, as it will allow the infusion of desirable traits and provides at least the potential to remove undesirable ones from the gene pool. 

Question: I have a 16-year-old maiden mare that has gas ulcers off and on. I have been treating her with omeprazole as she does very well with it and has been able to keep the episodes at bay for 3 ½ months. Unfortunately, it is now back and am looking to treat another round. I am considering breeding her in February. Should I be concerned?

Answer:EGUS (gastric ulcers in horses) has been carefully studied over the recent decade, and  our understanding of this very common syndrome has changed.  Omeprazole, (prilosec, gastroguard, ulcergard) js one in a class of drugs called proton pump inhibitors (PPI).  Although it has long been considered safe, recent evidence has suggested this type of compound must be used with caution.  In mares, the recommendation is: “The safety of omeprazole in pregnant and lactating mares has not been determined. Do not use in pregnant or lactating horses unless benefits outweigh the risks. Avoid use in foals less than 4 weeks of age.”  In addition, horses experiencing multiple bouts of EGUS–even those that have responded to PPI’s in the past–may benefit from other management techniques with lower to no risk. Slow feeders and natural products that elevate gastric pH (Aloe Vera juice and some seaweed extracts) have been a quite effective part of EGUS management. 

To make things just a bit more complicated, sixteen-year-old-maiden mares can be a challenge on several levels. Older mares, especially maidens over the age of thirteen or so, will commonly be difficult to impregnate, so you are going to need help. You should seriously consider starting artificial lighting now. Sixteen hours of darkness and eight hours of light (bright enough for her to read a newspaper in every corner of her stall) will stimulate most mares to produce a normal ovulation cycle by the first of February.  Your local AAEP veterinarian can guide you through this aspect of equine reproductive and nutritional management.  Good luck, we hope you have a new mouth to feed in 2020!