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Mare care: Equine producers have many considerations before foals arrive

by Wyoming Livestock Roundup

As equine producers across the world begin to see the light at the end of the tunnel that is spring breeding season, it is important to remember the unique needs of broodmares. With the horse market as a whole trending upwards, including stallion fees, it is critical to protect the investment growing inside mares.  

Ultrasounds and abortions 

The American Association of Equine Practitioners (AAEP)  reports, “During the first 30 days, there is a 10 to 15 percent chance the embryo will be resorbed. Stress, illness, uterine infection, hormonal abnormalities, the presence of twins and other factors have been implicated in early embryonic loss.” 

According to the American Quarter Horse Association (AQHA), up to 15 percent of broodmares safe in foal at 45 to 60 days lose their pregnancies by late fall.  

“This is often so late in the breeding season that there is not sufficient time for a veterinarian to determine the cause of the lost pregnancy, treat and correct the problem and rebreed the mare,” AQHA notes. “As a result, the owner loses an entire year.” 

The Merck Vet Manual notes twinning is the most common noninfectious cause of abortions in horses. Early detection of twins allows for the elimination of one embryo, while allowing the other embryo to develop normally.  

AAEP recommends owners ultrasound at 14 to 16 days to detect twins and remedy the situation before it is too late. 

Body condition score 

Similar to beef cattle, mares should be kept in moderate condition. Body condition scores (BCS) too low or too high can cause major issues prior to and during gestation. 

AQHA reports a mare in moderate to fleshy condition will be better prepared to provide adequate milk for her growing foal and will breed back quicker than a thin mare.  

“A mare should have at least a body condition score of five,” according to AQHA.  “She should have a level back and slight fat cover over the ribs, and fat should be evident along the sides of her neck and behind her shoulder.”  

AQHA notes mares with too much condition often produce less milk and therefore their foals will gain less weight. 

“A healthy mare in good flesh will gain nine to 12 percent of her original body weight during pregnancy. For example, an 1,100-pound mare should gain roughly 100 to 130 pounds during the course of her pregnancy,” AQHA notes.  

Nutritional needs  

During the last four months of pregnancy, the foal will grow rapidly.  

“To accommodate this growth, the mare’s energy needs will increase,” according to AAEP. “Even so, special nutritional supplements are probably unnecessary. Good-quality hay and forage should remain the bulk of the expectant mare’s diet.”  

Concentrated feeds, such as grains, may be added to the ration to bolster energy intake without adding excess bulk, AAEP adds. AAEP recommends using body condition as a guide to how the mare is faring, and adjust the ration accordingly.  


“Four to six weeks prior to expected foaling, mares should be vaccinated for tetanus, eastern and western equine encephalomyelitis or sleeping sickness, West Nile virus, rabies, equine influenza and equine herpes virus,” AAEP reports.  

This not only benefits the mare but also the foal, as the mare will pass antibodies to these diseases through her colostrum to the newborn. 

AAEP notes in mid-to-late pregnancy, mares should receive rhinopneumonitis (EHV-1) vaccinations.  

Foaling considerations 

The average length of pregnancy in the mare is 338 to 343 days. However, normal gestation can range from 320 to 380 days.  

Mares provide clues that they will soon give birth. However, the timetable is far from absolute.  

“Some mares may show all the signs like clockwork, others show practically none,” AAEP warns. 

Such signs include the udder filling with milk two to four weeks prior to foaling, the muscles of the vulva and croup relax and teats become engorged four to six days prior to foaling.   

AAEP notes waxing of the teats occurs one to four days prior to foaling. Some mares may begin exhibiting symptoms similar to colic, such as restlessness and kicking or biting at their stomach. This is often the first stage of labor, but if it persists for more than a couple hours, a vet should be called as colic is not out of the question.  

 “Every effort should be made to be present during foaling. In most cases, owners will simply need to be a quiet observer,” AAEP notes.  

Callie Hanson is a corresponding writer for the Wyoming Livestock Roundup. Send comments on this article to  

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