The mare cycle – that's how it works with estrus

They can be very sensitive and even buck. Mares in heat can spoil the riding experience. However, not all mares show the typical signs, and some even need a little help to become pregnant.

INHALT
What does a mare's cycle look like? Recognizing and understanding the time of the horses
What does a mare's cycle look like?

According to textbooks, mares reach sexual maturity at around 18 months of age. Breeding maturity, i.e. the point at which the mare is physically developed enough to become a mother, is usually reached at three years of age.

The cycle begins with estrus, which occurs every 21 or 22 days and can last between two and twelve days. During estrus, the eggs mature and ovulation occurs on the last or penultimate day of estrus. The entire phase is also called estrus. This is followed by diestrus, the interval between estrus. Now the corpus luteum is active and produces progesterone. The uterus is ready to receive a fertilized egg. If no embryo implants, the cycle starts again.

Mares are seasonally reproductive and do not go through menopause. In the northern hemisphere, the estrus cycle begins in spring and ends in fall. Most mares do not ovulate at all from November to February.

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Recognizing and understanding the time of the horses

The mare is "flashing," as it is called in technical jargon. Her labia are swollen. She stands with her legs apart, moves her tail to one side, and exposes her clitoris while secreting a fluid consisting of urine and mucus.

The mare's hormonal situation is now changing, and so is her behavior. The hormones stimulate the ovaries via the pituitary gland to form follicles. The follicles in turn produce estrogen, which prepares the uterus for implantation. Towards the end of the estrus cycle, another hormone triggers ovulation. During these physical processes, the mare may be very sensitive. This can manifest itself in actual bitching or in her being particularly needy. Brushing under the belly, touching the loin area more firmly, and sometimes even lifting the hind legs can lead to conflicts between horse and human during this time.

Some mares are also tense when being ridden during this phase. They "tail wag" more and shy away from work. Sometimes it can be helpful to just move them around gently during this time or to come up with an alternative program.

However, there are also mares who show no signs of being in heat and appear mostly balanced. In fact, this can also be caused by cycle disorders, which make it difficult to foal the mare. Sometimes external circumstances, such as stress, prevent the foaling from happening. Plenty of sunlight and relaxed hours on lush pastures in a herd can help the mare return to a regular cycle.

Of course, a veterinarian can also provide medical assistance for mares with severe heat problems. There are medications available to suppress a strong heat with resistance when handling or riding. It is important to be aware of the doping implications in competitive sports.

Persistent estrus should always be discussed with a veterinarian. Not only can a mare that is constantly in heat, squealing and whinying be very stressful, but ovarian tumors can also cause real distress in this case.