Broodmare Management

By Lew Strickland, DVM MS DACT

Broodmares represent a large financial and time commitment, even when the mare conceives quickly and maintains the pregnancy. Mare owners and their veterinarian should carefully evaluate the mare for conformation, suitability to purpose and to breed registry rules, performance ability, temperament, and reproductive soundness prior to breeding. If the owner decides the mare has qualities worth passing on to her offspring and is willing to make the commitment in time and money, then proper broodmare management can increase the chances of producing a healthy foal. Including your veterinarian in broodmare management can greatly increase the chance of success.

Start with a healthy mare

Good nutrition, appropriate parasite control and vaccinations, and regular hoof and dental care contribute to the overall health of the mare. Starting with a healthy mare will go a long way towards breeding success. The intended broodmare should be in a moderate to moderately fleshy body condition. In this body condition, her ribs can be felt but not seen, she should have slight fat deposits around her tail head and withers, and her body parts should blend together smoothly. Research has shown that mares in a thin body condition have more trouble conceiving and maintaining a pregnancy than those in a moderate to fleshy condition.

Routine health care procedures should be performed on open and lactating mares. Mares should remain current on their vaccinations and all farms should consult with their veterinarian about an appropriate parasite management program. Parasite management is not a one-size fits all approach. Instead, each farm should have an individual parasite management plan depending on the number and age of animals present, the stocking density, and the environment. Mare owners should also check with their veterinarian and with the breeding farm manager about any additional vaccinations or health care procedures that are recommended or required before a mare enters their facility. If the mare is traveling out-of-state for breeding, she will need a health certificate and current Coggins test.

Prior to the breeding season a mare should have a breeding soundness evaluation performed by a veterinarian experienced in equine reproduction. The veterinarian can examine the internal and external reproductive conformation of the mare, and identify and correct some reproductive problems. Uterine culture for infectious organisms and cytology (cell examination) can detect uterine infections that will prevent pregnancy, and a biopsy (tissue sample) of the uterine wall can evaluate the mare’s probability of conceiving or maintaining a pregnancy. When these procedures are performed before the breeding season, many problems can be corrected so that the mare may become pregnant during the breeding season. Foaling mares should also have a veterinary exam prior to rebreeding if they had a dystocia (foaling difficulty), retained placenta (sack surrounding the foal), or abnormal vaginal discharge after foaling.

Timing of breeding

Mare owners need to have some way of detecting or inducing estrus in their mares.  Delivering the mare to the breeding farm immediately prior to an estrus can reduce expenses at the breeding farm. Or, if the mare is going to be bred with shipped or frozen semen, it is crucial to accurately predict estrus and ovulation times to obtain the semen and inseminate the mare at the correct time. Without access to a stallion, owners must observe their mares closely for signs of estrus each day. These signs include increased interest in other horses, frequent urination, posturing (rump lowered, one or both hind feet supported by the toe only) and “winking” (frequent eversion of the vulva to expose the clitoris). Some mares will show estrus to a gelding or even to another mare.

A veterinarian can help pinpoint estrus through rectal palpation of the reproductive tract or through ultrasound imaging of the ovaries and uterus. A veterinarian may also prescribe various hormone treatments to induce estrus or to help schedule the time of the next estrus. After the mare is in estrus and inseminated with semen, the veterinarian can induce ovulation with a hormone injection so that the timing of the insemination is favorable for fertilization.

After ovulation, the egg has a relatively short life span for breeding purposes (about 12 hours), but the sperm can live in the mare’s reproductive tract for 48 hours or longer. So the best option for fertilization of the egg is to inseminate the mare from between 36 hours before ovulation up to the time of ovulation. Breeding early post ovulation can result in pregnancy but is less effective than breeding prior to ovulation. Because the heat period is variable both between mares and within the same mare, predicting ovulation time can be a problem without the help of a knowledgeable veterinarian who can either palpate or ultrasound the ovaries to predict when ovulation will occur. 

Breeding Tips

Some tips to increase the horse breeder’s success are:
1. Start with a healthy mare in good body condition with good teeth and feet.

2. Avoid attempting to breed during the transitional period between anestrus and the breeding season. Most mares in the Southeast do not start normal cycling until about mid-March, so breeding during the transitional period may be a waste of time and resources. If you must breed early in the year begin an artificial lighting program in the fall so that the mare cycles early the following year.

3. Tease (expose the mare to the stallion to check for behavioral signs of estrus) frequently and regularly. If the mare does not seem to be cycling or you cannot detect estrus during the normal physiologic breeding season ask for veterinary assistance.

4. Breeding during foal heat (a fertile heat that occurs in approximately 5-12 days after foaling) has a greater chance of resulting in pregnancy when more time has elapsed between foaling and ovulation. This gives the uterus greater time for involution and repair prior to another pregnancy. Mares that are “early” on foal heat or that have dystocia or a retained placenta at foaling may not be good candidates for foal heat breeding.

5. Avoid pasturing mares on endophyte-infected fescue or feeding them hay from endophyte-infected fescue.
Endophyte-infected fescue causes a variety of serious reproductive problems in mares. There are varieties of endopyte-free fescue and fescue infected with a harmless variety of endophyte which are safe to feed broodmares. If you do not know if your fescue pasture is safe, it can be tested for toxicity. If it is toxic, it is safest to remove the mares from the pasture.

6. Inseminate the mare a minimal number of times. Utilize technologies available to inseminate at the best time for success and to help the mare clear inflammation from the uterus. A veterinarian experienced in equine reproduction can help identify the best time to inseminate your mare.

7. Visit your veterinarian for an initial pregnancy exam 14 to 16 days post-breeding. Have your mare’s pregnancy rechecked at day 30-35 and again at day 180.

After the mare is successfully bred, the owner should realize that their work is not finished. As during the prebreeding period, proper nutrition, health care and management of the mare is important to the health of the developing fetus. Mare owners who enter the breeding business with a clear understanding of the economics involved in breeding and stallion selection and who manage their horses carefully should have a successful and fulfilling experience.
Lew Strickland DVM MS DACT
Extension Veterinarian
University of Tennessee
Animal Science
Large Animal Clinical Science
Room 246 Brehm
University of Tennessee
2506 River Dr
Knoxville, TN 37996
865 974 3538

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