Hormones are the body’s messengers, travelling through the bloodstream to communicate between various glands and organs. They affect and regulate body functions and metabolism. These can have an influence on behaviour, most commonly, in-heat mares, and Cushings in older horses.
The several endocrine glands, from ovaries and testes to pituitary and thyroid, produce most of the hormones that drive body processes. The pituitary (called the master gland) at the base of the brain secretes a wide variety of hormones that control and affect growth and influence secretion of hormones from other glands.
There are drugs and quite specific herbs that can influence the pituitary gland. More on that later.
The Hormonal Mare
Is a condition where the mare’s behaviour is due to hormone disruption. Sometimes Ovaries are blamed for a range of problems, including lameness and training issues, so first rule out other causes. If she’s harder to ride or doesn’t perform well during oestrus, you may decide to just take it easy or give her time off on those days. But if you need to stick to a competition or training schedule, you may decide to control the timing of her heat cycle with hormone therapy. Some mares are reactive, hard to handle or unfocused in their work while in heat. Oestrogen brings the mare into heat and prepares her reproductive tract for breeding, while progesterone keeps her out of heat. In the non-pregnant mare, interaction of oestrogen and progesterone are the main factors that determine her behaviour, personality, and pain threshold. Again there are drugs and herbs that can influence the balance between oestrogen and progesterone as well as addressing the pain threshold by increasing serotonin levels.
Causes for Marish behaviour:
These may include:
- Underlying problems not related to your mare’s cycle, but possibly ovarian tumors. The most common type, the granulosa-cell tumor, can produce testosterone and other hormones that trigger aggression or “studdish” behavior, such as teasing other mares.
- Your mare may appear to be constantly in heat or never in heat where there may be an ovarian tumour or cyst which can be surgically removed.
- If you find that your mare’s behaviour fits the normal cyclical, seasonal heat pattern—she’s great for two weeks and difficult the next week—odds are it’s heat-related.
- During the transition from one phase to the next, when both estrogen and progesterone are often present in fairly high levels, some mares become more sensitive to touch, aggressive and may bite, kick, flinch or squeal when being groomed or saddled.
- Some mares seem to be in heat all the time, due to hormonal imbalance. A long transitional heat which may last 30 days or longer. She will usually come into a normal heat at the end of this transitional period, and cycle normally through the rest of the breeding season. She may also go through a long transitional heat at the end of the breeding season.
- Mares exposed to continuous light in barns (to keep hair coat short for showing) sometimes lose their ability to cycle normally and may show persistent or long heat periods.
Clinical and behavioural signs:
- Excessive squealing when another horse comes near her
- She may behave so erratically that she is dangerous to be around.
- You may notice that she’s increasingly distracted.
- She may develop a passionate attachment to one of her barn buddies and whinny constantly if that horse is out of sight.
- She may squeal and kick out at the slightest provocation.
- She may also become sensitive in her back and sides and react either with a buck or kick at your leg when you apply leg pressure.
- Some mares are unusually spooky as oestrus approaches. Some become irrational when separated from other horses, or more focused on other horses than on paying attention to the person riding or handling them.
- Hormone Therapy
Medications to control the cycle are available by prescription from your veterinarian. Most of these medications don’t affect long-term fertility and, because most mimic hormones circulating naturally in your mare’s system, would not show postive in a swab.
- Progesterone. This is the hormone that dominates during diestrus and keeps the mare from coming into heat. There are various types, with varying effectiveness. These medications should be used cautiously in mares with a history of uterine inflammation or infection because they can make that condition worse. Progesterone injections are given into the muscle and usually take effect within 24 hours. The injections delay heat anywhere from five days to a month or so,
- Regu-Mate(altrenogest) is a liquid oral medication that provides a synthetic source of progesterone which will prevent your mare from returning to eostrus as long as she continues to get a daily dose. When you stop, she’ll probably come into heat within five to 10 days.
- Depo-Provera is sometimes given, but studies have shown it to be less reliable than other forms of progesterone as a way to suppress oestrus in mares.
- P&E. Progesterone combined with estradiol 17B (a form of estrogen) may help when progesterone alone doesn’t solve behavior problems. This happens in some mares, because progesterone delays the onset of heat but doesn’t stop ovarian activity so follicles can still develop in the ovaries. Adding estradiol suppresses follicular activity.
- Oxytocin is a new method for keeping mares out of heat, This naturally occurring hormone is also used to suppress heat. It can delay oestrus for 30 days or more. Given at the right time oxytocin prolongs the life of the corpus luteum so that it continues to produce progesterone, keeping the mare out of heat. Oxytocin is the hormone that helps a new mother bond with her baby/foal and is calming.
Other Treatments for Marish behaviour:
- “Train through” the problem as much as possible before resorting to hormone therapy. Much of the bad behaviour in young in-heat mares can be due to immaturity, lack of training, and inexperience. Most can be trained out of this seasonal sensitivity.
- The young in-heat mare should not be punished excessively if she’s obsessed with other horses or has a hard time concentrating on her work while under the powerful influence of oestrogen.
- The insertion of a small glass ball (marble) into the uterus. The presence of the glass ball (similar to an embryo of that size) causes the CL (corpus luteum) on the ovary to remain, continuing to produce progesterone—the hormone that keeps the mare out of heat. To bring the mare back into heat, she can be given prostaglandin and the marble can be removed.
- They benefit from a soft voice and a gentle touch as much as we do. And the following herbs can provide very effective relief from hormonal imbalances. In humans this increases oxytocin levels.
Natural and Herbal Treatment
Herbs can be very effective in addressing hormonal problems in mares as well as in stallions.Herbs tend to be cumulative in effect, which means they can take anywhere from several days to a few weeks to show optimal benefits. Once your horse has been on an herb for a month, you can often drop back to a lower maintenance dosage, which is generally one-half to two-thirds the previous dose.
- Chaste tree berry (Vitex agnus) contains. Flavonoids, alkaloids, diterpenoids, vitexin, casticin and steroidal hormone precursors have been isolated from the chemical analysis of the berries. These compounds work on the pituitary gland which would explain its effects on hormonal levels. That the active ingredients in this herb works by regulating the pituitary gland, which sends signals to other glands instructing them of how much of each hormone to make. A study has shown that extracts of vitex agnes can bind to opiate receptors; this could explain why intake of vitex reduces PMS discomforts and is slightly sedating . Research shows that it increases female progesterone inhibiting male androgens. Bitter sweet slightly astringent relaxant herb that regulates hormonal functionsand that the berries increase the production of luteinising hormone and prolactin as well as the production of the hormone progesterone. It is a natural sedative and has anti-spasmodic properties. Acts on the adrenals making them less reactive.
- St John’s Wort This herb can be used in conjunction with vitex agnes to help address some of the stress response and separation anxiety that can occur with mares that are excessively herd-bound. Mares naturally derive safety by being in a herd so intelligent handling and careful patient desensitising is recommended. Raised serotonin levels from this herb will also help the mare feel more relaxed and contented in her surroundings.
- Chamomile (Matricaria recutita )
Chamomile is an emmenagogue with is calming and anti-inflammatory which will alleviate any discomfort she is experiencing. It can help restore the normal heat cycle. Mildly sedating particularly suitable for the digestive system. Its effect on the Central Nervous System NS/sensory effects are due to chemical compounds present within chamomile which bind to GABA receptors, modulate monoamine neurotransmission along with neuro-endocrine effects.
- Motherwort (Leonurus cardiac)
Acts on the nervous system to create a calmer, less irritable mare. It will gently strengthen her circulatory system while balancing her seasonal fluctuations and irritability. Motherwort is sedating.
- Red clover (Trifolium pratense)
and hops (Humulus lupulus) Both these herbs have estrogenic effects and can be used to calm anxiety and reduce irritability. Horses especially love the taste of red clover tops – a few every day can make a world of difference. Mares will self medicate on red clover tops and are noticeably calmer.
- Lady’s mantle (Alchemilla vulgaris)
This herb is known as a female tonic, and is well known for its ability to benefit the uterine system. It is strengthening and regulating, and has been used extensively to enhance fertility. Research has shown it to shrink fibroids.
- Red Raspberry (rubus idaeus)
The leaves are a uterine tonic herb and contain fragrine, a potent alkaloid that strengthens the uterus and entire pelvic region. They are also very calming to the nervous system, and can be used throughout a heat to encourage fertility and settle your mare.
- European angelica (Angelica archangelica)
and dong quai (Angelica sinensis) These can be used in conjunction with chaste tree or on their own to help balance irregular heats and reduce unpleasant symptoms caused by hormonal imbalances. These warming, strengthening herbs have a balancing action on the female hormonal system, although they do not have hormonelike effects themselves. Both angelicas contain coumarin compounds, which help relieve muscle cramping and painful menstruations while strengthening the circulatory system. As with chaste tree, do not use these herbs during pregnancy or mating. Although angelica is not an anticoagulant, horses on blood thinners should not take it because it may decrease the ability of the body to metabolize prescribed blood thinners.
Herbs to Help with Hormonal Pain and Discomfort:
- Devil’s Claw may be used if your mare is sensitive over her flanks and is reactive to being ridden or girthed up. Devil’s Claw is an effective anti-inflammatory.
- Thyme (Thymus vulgaris), stinging nettle (Urtica dioica,), Thyme and stinging nettle are both anti-inflammatory and cleansing to the body. They are safe to use long term without any side effects.
- White willow and meadowsweet are natural sources of salicylic acid, the active ingredient in aspirin. They are much gentler on the stomach than aspirin, and can also generally be used long term without causing any harm to the body.
DISCLAIMER : Hira Laboratories will not be held responsible for the use or misuse of any information written here or any products listed. We recommend that either a qualified herbalist or your animal professional carry out diagnosis and subsequent treatment. Herbal remedies must not be given not be taken in conjunction with other medication with out consulting a medical professional.