Double Trouble, Part I

Although live twin foals are a rare and exciting occurrence, they are not something to hope for.

From a veterinarian and a breeder standpoint, twins are never a blessing. Journal photo

Teseres was 8 when she was bred for the first time in 1997. She had been successful in the show ring in New Zealand, and her owner, Sarah Clarke, wanted nothing more than to breed her beloved mare. Sarah bred Teseres and had her checked with ultrasound twice to ensure that she would produce a single healthy foal. The sonograms showed no signs of abnormality, and Sarah counted the days until the birth of her beautiful foal. Ten days past her due date, Teseres delivered a stillborn foal in the middle of the night and retained her placenta. When Sarah discovered the dead foal the next morning, she was not only disappointed by the loss of the foal, but she also feared for the safety of her mare. She called her veterinarian, and to Sarah’s surprise, he delivered a second stillborn foal and had to manually remove the placenta, because Teseres was no longer having contractions.

Sarah gave Teseres a month to recuperate and then bred her again. Sarah’s veterinarian checked the mare by ultrasound and discovered Teseres had conceived twins again. The veterinarian attempted to reduce the smaller of the two embryos to try for a single-foal pregnancy, but both embryos were absorbed. Sarah decided to postpone breeding her mare back until the following season. Teseres conceived twins for a third time. The veterinarian again tried to reduce one, but both embryos were lost. “Words do not express the way I felt at that point,” Sarah says.

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Double Jeopardy

From a veterinarian and a breeder standpoint, twins are never a blessing. Twins are caused by double ovulation. This means that two separate eggs are fertilized by two separate sperm and grow into separate fraternal embryos, as opposed to one splitting and becoming two genetically identical embryos. Teseres is a textbook example of the trouble twins can cause. Dr. Ben Espy, a board-certified reproduction veterinarian in San Antonio says many mares like Teseres conceive and abort twins without detection. Mares that abort twins after three or four months of gestation are likely to have a retained placenta due to the trauma of foaling. Although the retained placenta was not a major problem for Teseres, it was for Valerie Baxter of North Pole, Alaska, and her Thoroughbred mare, Ten Chimes.

Valerie bred “Ricki” to a Quarter Horse stallion several years ago, and the mare conceived twins and aborted both foals during her eighth month of gestation. She had to undergo aggressive antibiotic treatment, as well as periodic doses of oxytocin, which is a natural hormone used to induce uterine contractions to pass the retained placenta. Finally, three days later, the mare delivered the placenta. Valerie says she feels very fortunate that the cold Alaskan climate prevented Ricki from becoming infected. Dr. Espy says even if a mare keeps both embryos through the early (28 days) part of gestation, there is a 90 percent chance she will abort both foals before they become full-term. Not only is the loss of a season detrimental to a breeder, but it is also harmful to the broodmare because a mare’s uterus is healthiest when it is in use, Dr. Espy says. An empty uterus accumulates scar tissue, making it more difficult for the mare to conceive the next time she is bred, he adds.

Although Teseres was by no means lucky during her gestation period, according to Dr. Espy, she was better off losing the foals. Twins can cause additional stress to the broodmare. She not only has to feed two foals, but she also has to protect and teach two foals. Due to the added stress of twins, mares are likely to reject one of the foals. In most sets of twins, one is a runt. Horses are prey animals, and their instincts tell them to leave behind any animal that will slow the herd. They are instilled with a survival-of-the-fittest mentality. The runt is generally weaker and slower because it was robbed of its mother’s nutrients by the larger foal while inside the womb. The mare is also limited on her supply of colostrum, a high-energy milk containing antibodies to protect against infection. This is especially true if the twins are premature. This may also affect her decision to reject the smaller foal to preserve the healthier one.

Raising Twins

If the mare rejects a foal, this means either the owner or a mare that has lost her foal becomes the surrogate mother. Having another mare raise the orphan is the most natural choice. If the owner chooses to raise the foal, she has two options: pan or bottle feeding. Dr. Espy says foals require between one and two pints of colostrum in the first 24 hours of life, while the special pores in their intestines allow them to absorb the substance.

If you're planning on breeding your mare or have already bred her, you should check out our Horse Reproduction e-book. You'll find tips on how to care for your pregnant mare and prepare for the foaling date.

“Horses are born without an immune system,” Dr. Espy says. “The only way they can obtain one is through the mare’s colostrum.”

Although colostrum is absorbed after the first 24 hours, it is crucial during the first six to eight hours of the foal’s life. During that time frame, the foal absorbs 85 percent of the colostrum it needs to survive. Therefore, when owners are surprised with twins, they must begin finding colostrum as soon as the foals are discovered. Mares that foal twins generally only have enough colostrum for one foal. So twin owners must either obtain colostrum from another mare or purchase it from a colostrum bank at an equine neonatal facility. The intake of colostrum can also be substituted with the administration of intravenous plasma. An average-size foal will require between one and two liters of plasma. Dr. Espy says the average cost of colostrum is $250 per pint, and the average cost of a plasma treatment is approximately the same. When you double that figure to get the amount each foal requires and include your traveling expenses, your bill can be pricey.

Even if your twins get the colostrum they need to survive, they are still in danger. If they are bottle-fed, there is a risk of aspiration (inhaling milk into the windpipe instead of the esophagus.) Bottle-fed foals may also have trouble fitting in socially with other horses because they take after their human mother. Premature foals also have the usual risks of cleft palates that increase the risk of aspiration, underdeveloped respiratory systems and orthopedic defects.

“Twins are extremely expensive, and their prognosis is poor,” Dr. Espy says. Valerie agrees with Dr. Espy. “I paid more in vet fees to lose the twin foals than I did to breed just one foal successfully,” she says.

Regal Holiday Dude, owned by Vickie Tessman of Perry, Oklahoma, was able to provide adequate colostrum for her twin fillies born in 2006. However, the twins were still expensive. Vickie took special care of “Holly,” feeding her three times per day for the first three weeks of the foals’ life. Holly, a 22-year-old mare, also nursed the fillies for eight months, which was longer than the elderly mare was accustomed to.

The mare was not rebred the following breeding season. Vickie’s tender, loving care and Holly’s “good mama” abilities allowed Images Small Kiss and Justa Pacific Jet to beat the odds and grow into healthy horses. The fillies are in the 10 percent of all double ovulations that result in the birth of two healthy foals, even though “Daphne” and “Daisy” will never be big mares.