Mares with unknown or poor reproductive histories should be evaluated by using the standard practices of palpation, ultrasonography, intrauterine culture, cytology, and biopsy well ahead of the breeding season i.
Early detection of reproductive abnormalities, followed by proper therapy and management changes, usually results in more consistent and acceptable conception and foaling rates. Conception rates are highest when mares are inseminated 36 hours before and up to the time of ovulation. As previously stated, ovulation most frequently occurs 24 to 48 hours prior to the end of estrus. Ovulation can be easily missed unless managers are precise in estrus detection and maintain accurate records.
Managers often start breeding mares the second or third day of estrus heat and continue every other day until the mares goes out of estrus. However, palpation and ultrasonography can aid significantly in calculating the proper breeding time. Several management techniques are used for pregnancy determination. One of the simplest ways is to watch for signs of heat. A mare may be pregnant if she exhibits no signs of heat 18 to 20 days after her last ovulation.
However, some mares may not cycle because of follicular or corpora luteal abnormalities, or they may have silent heat periods in which external signs of estrus are not evident. These problem mares would not be bred again if absence of heat was the only factor used to determine pregnancy. Because of these situations, other methods for pregnancy determination are commonly used. Mares are most often rectally palpated 18 to 45 days following the last day of insemination. In recent years, real-time ultrasonography has gained attention for use in pregnancy determination.
Ultrasonography is normally used following the 14th day post-breeding, but it can detect pregnancies as early as 10 days post-ovulation. As mentioned earlier, the ultrasound can also be used to detect estrus and follicular development, and it can be used with mares that have reproductive tract abnormalities or abnormal cycles Figure 3. Anestrus — The period when most mares show no signs of reproductive activity at all.
Anestrus begins in the fall and peaks around December. Diestrus — The period when the mare is not receptive to the stallion usually lasts about 17 to 19 days. Estrous — Refers to the entire reproductive cycle.
The average length of the estrous cycle is 21 to 23 days from one ovulation to the next. Palpation — The procedure of reaching in through the rectum and feeling the ovaries through the rectal wall to detect the presence of a follicle.
There are several management tools used to bring about the onset of the breeding season or to alter the estrous cycle itself. The easiest light management program is to use lights at the end of the day to extend the perceived day length or photoperiod to 16 hours.
This practice entails turning on an artificial light source 30 minutes before sundown. The light source should be turned on to supply enough additional light to produce a total 16 hours of daylight natural and artificial. There is a lag period of 60 to 90 days between the onset of daylight extension and first ovulation. Therefore, if February-March ovulations are desired, mares should be started on the lighting program before December Perception of day length must be constant from day to day; the use of automatic timers is of benefit.
Also, using too much light can cause adverse effects. Mares that are exposed to continuous light will not cycle properly. Light intensity should be a minimum of two foot-candles, which is comparable to one watt bulb for a 12 x foot stall. Floodlights can be used on outside pens. This does depend on a few factors, including the season. Their breeding season typically starts in April. It is also dependent on whether or not the filly is around other horses, particularly mares that are in or getting ready to be in heat.
Stallions are another possible cause of earlier than normal heat, while the season can make a filly go into a first heat later. Mares typically have a three-week estrus cycle. They can be in heat for as little as two days or as many as ten days.
This will last until the days begin to grow shorter again, usually around September. This cycle may be different depending on location.
In the farther northern part of the northern hemisphere and the south part of the southern, the cycling time will be shorter. In the middle parts of the globe, it may be longer. Mares have an eleven-month gestation cycle, and all foals in the Northern Hemisphere are considered born on January 1 of the year of their birth. So if your foal is born in May , on January 1, , it is deemed to be one year old. Ideally, you want your mare to have her foal as early in the year as possible.
For horse racing, a couple of months can make a huge difference. For example, most tracks have races for two-year-olds in the fall season. For horses born late in the year, they could be matched against horses six or seven months older or miss their entire two-year-old season. Age is also important in many other equine disciplines that horses compete by age, such as dressage, jumping, and barrel racing futurities.
Mares in heat can be a problem, especially for those new to horse ownership. There are a number of things that they may do or not do.
She might also clamp her tail. During the breeding season … her ovaries would contain the appropriate structures related to the stage of her cycle. If she is in heat, she should have a big follicle and uterine edema fluid swelling , and her cervix would be relaxed. If she is out of heat she should have a corpus luteum CL, the progesterone-producing structure formed after the follicle releases the egg in the ovary and her cervix should be tightly closed, with no edema. We can also pull blood and look at progesterone levels.
A mare that is not in heat should have elevated progesterone. Affected mares not only act and sound like stallions but also often develop a cresty neck. If it turns out the mare does have a tumor, removing the affected ovary will fix the problem. The owner might opt to have both ovaries removed, depending on plans to breed her, says Ferris. If the owner wants future foals, the mare can reproduce normally with just one ovary.
Once the remaining ovary recovers, the mare should resume normal cycles, say our sources, and behave as she did before the tumor. After the veterinarian examines her, he or she administers the appropriate antibiotics to resolve the infection. Mares that pool urine in the vagina or uterus do the same thing—again, due to inflammation. A mare with poor perineal conformation might aspirate air into the vulva windsucking, which also invites contamination and vaginal, uterine, or cervical inflammation , and if the anus is set back, or recessed, from the vulva, feces might fall into the vulva.
The pelvic brim can serve almost like a shelf, with the anus above it and the folds of the vulva below. In a normal, healthy mare, the anus and the vulva align vertically. Some mares show colic symptoms because of painful ovulation. Not all mares that colic are examined via rectal palpation, so it may be hard to link painful ovulation and colic if the mare is simply treated for colic and her ovaries are not examined. The non-steroidal anti-inflammatory drugs your veterinarian might prescribe to relieve colic pain also generally ease ovarian pain.
How to Halt Estrus Equine veterinarians have several ways to prevent estrous behavior. The classic method is daily oral administration of the progestin altrenogest e.
Other options include injectable progesterone products. The downside, as with any injection you have to give repeatedly, is the risk that some mares could develop soreness at the injection sites.
The mare is seasonally polyestrus, meaning that she undergoes regular estrus cycles during late Spring, Summer and early Fall and none during the Winter. This is nature's way of preventing the arrival of a foal during the harsh Winter weather. During this period, the mare undergoes a series of cycles, each approximately 22 days in length. The estrous cycle is divided into two physiological parts: estrus and diestrus.
The estrus, or "heat" segment of the cycle, is three to seven days in length and is the time when a mare is receptive to the stallion. Estrus must be accurately determined because it is the period during which the mare must be bred in order to conceive.
Ovulation release of the egg for fertilization usually occurs 24 to 48 hours before the end of estrus. Conception rates are highest when the mare is bred 36 hours before and up to ovulation. It includes the vulva, vagina, cervix, uterus, oviducts and ovaries. Changes in the anatomy or interruption in the function of any section can contribute to reproductive problems.
The vulva is the exterior opening to the reproductive canal. It consists of the labia, clitoris and the vestibule. The construction of this region is important because it serves to protect the mare from the entrance of air and other contaminants into the vaginal vault.
The vagina consists of a six to eight-inch long muscular mucus membrane-lined tube which connects the vestibule of the vulva to the cervix. The vaginal tissues are extremely elastic in order to accommodate the penis during breeding and the foal during birth. The cervix is approximately four inches long and appears as a circle of folded tissue at the anterior surface of the vaginal vault.
The uterus is a multi-layered, hollow, Y-shaped organ. The base of the Y is called the uterine body, while the two branches are called the horns.
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