Harper on Mares
Harper on Mares

Broodmares Affect Foals’ Behavior

by Dr. Frederick Harper, Extension Horse Specialist
Animal Science Department, University of Tennessee, Knoxville, TN

“Oh, he looks just like his father,” Aunt Patsie says. “And his personality is just like his mother’s.” You have heard comments like that at a family reunion.

But it is also a question that broodmare owners often ponder. Where does a foal get its disposition? Some horse breeders attribute these characteristics to the sire, while others proclaim that foals take after their dams.

Research from the University of Georgia has given us a glimpse into the pecking order (rank) of mares and foals. They studied 14 mare-foal pair of Quarter Horses, Arabians, a Hanovarian and a Saddlebred. Mares and foals were kept in a 25-acre pasture. Mares were brought into a small paddock when they were bred and the foals weighed. The mares had been kept together for 12 months before foaling.

Researchers made multiple 30-minute observations weekly of each mare-foal pair noting aggressive behavior, such as head threats, bites and kicks. They also studied non-aggressive behavior, and spatial relationships. Foals were studied with their dams as sucklings and after weaning up to 6-months of age. Foals were weaned at 4 months of age.

Pecking order is determined by aggressive behavior.

A foal’s rank before and after weaning was correlated to their dam’s rank. Foals high on the pecking order before weaning were likely to be high on the pecking order after weaning. And high-ranking foals were out of high-ranking mares.

Foal rank was not affected by sex. Foaling order affected pre-weaning rank but did not affect post-weaning rank. Foals that were aggressive before weaning were likely to be aggressive after weaning. Foal rank after weaning was not affected by weaning order.

Foals usually budded with other foals out of mares that were preferred by their dams. After weaning, foals tended to stay in close proximity to these same playmates. This behavior would tend to minimize the stress of weaning if foals are allowed to stay in the herd which was familiar to them.

The dam of a foal influences its dominance rank or pecking order in the herd as well as the foal’s choice of buddies.

In our man-made environment of managed horses, maternal influences still affected the behavior of the foal.

Why is this information important? If you own several mares and foals, you can use this information for better management. If you keep foals for future showing and performing, you want the best prospect. But you also want a foal with a good disposition that will be easy to handle and train. You probably also want to keep replacement fillies out of less-aggressive dams.

The tremendous interest in youth and amateur classes in shows has resulted in the demand for suitable horses. A beginning rider does not need a horse that is difficult to handle.

Foals from mares low on the pecking order, as well as their dams, probably get less supplemental feed and are more likely to be injured. You may need to separate them from a larger herd and place them in another pasture.

Remember that mares of similar rank tend to buddy together, as do their foals. Select mares that are compatible to be kept together.

In drought years or dry summers when you must provide supplemental feed, separating aggressive mares helps the shy ones.

Harper on Mares

Colic in Pregnant Mares

by Dr. Frederick Harper, Extension Horse Specialist
Animal Science Department, University of Tennessee, Knoxville, TN

Colic and founder are as dreaded by horse owners as a diagnosis of cancer is for us.

Colic in a pregnant mare is a traumatic event to a mare owner. Even if she lives, she may not have a foal.

In the pregnant mare, colic is the condition that most often requires veterinary attention. But fortunately, most colic cases in pregnant mares pose little danger to the mare or fetus and require minimal treatment.

About 82 percent of mares medically treated for colic survived in one study, but only 44 percent of the mares survived colic surgery. The survival rate was 59 percent for mares in the second trimester of pregnancy, 50 percent for mares in the third trimester and 30 percent for mares near foaling.

Loss of a fetus is a major concern when pregnant broodmares colic. The abortion rate in mares after they have coliced is 16-18 percent, which is slightly higher than in pregnant mares that do not colic. Abortions tend to occur up to 60-days after colic surgery.

When mares were only treated medically for colic, the abortion rate was 12 percent, but was nearly 20 percent if mares had colic surgery. Another study reported that abortions were four times more likely in pregnant mares treated for colic.

Abortions after colic often follow signs of endotoxemia. Clinical signs of endotoxemia, such as depression, anorexia, rapid heart rate and dehydration, occur in a high percentage of mares that abort. Endotoxins from bacteria present in the intestinal tract are not normally absorbed into the circulatory system. If endotoxins are absorbed into the blood stream, the color of the mucus membranes is altered, capillary refill time prolonged and heart and respiratory rates increase. Experimental endotoxemia results in embryonic loss in pregnant mares.

A number of unique conditions occur in pregnant mares that can cause colic as compared to the normal causes of colic in other horses. Colic in pregnant mares is a disorder of the digestive or reproductive tracts.

The most common digestive-tract problems in pregnant mares are large colon impaction, displacement and twisting. Large colon impaction in pregnant mares can be due to feed changes. The lack of space due to growth of the fetus and its associated tissues create pressure that may increase risk of impaction.

Large colon twisting is the most common cause of colic surgery in pregnant mares. Mares in the first 100-days after foaling appear at greatest risk of this type colic. Mares which have recently foaled and have violent colic signs and abdominal distension should be suspected of large colon colic. Increase in grain intake for milk production and a decrease in forage intake at that time may result in re-positioning of the large colon.

Causes associated with the reproductive tract are uterine twisting, contractions associated with expulsion of fetal membranes, prolapse, tears and arterial hemorrhage.

Mares normally have some abdominal discomfort with normal expulsion of fetal membranes and uterine involution after foaling. But this is of short duration. A retained placenta can result in mild, intermittent colic.

Uterine twisting is uncommon but must be considered when mares show mild-to-moderate signs of colic in the last trimester. The fetus is at risk with uterine torsion. Uterine prolapse normally occurs immediately after foaling but can occur several days later. Uterine tears are, an uncommon cause of post-foaling colic, normally associated with dystocia or even normal delivery.

Mares show extreme pain with rupture of muscles of the ventral abdomen or prepubic tendons.

Signs of mild-to-moderate colic pain in pregnant mares includes yawning, pawing, dullness, lying down and occasional rolling. Most colic in pregnant mares occur within two weeks of changes in feeding or exercise programs.

Prevention of colic in pregnant mares begins with daily observation of them and immediate veterinary assistance at the first signs of colic. Do not make rapid changes in the feeding program of pregnant mares, make sure they get plenty of exercise and have clean, fresh water at all times.