Oh those hormones!

As we get well into spring and early summer mares are stimulated to cycle and should do so regularly every 21 days or so. Occasionally things get a little out of step. This can cause uncharacteristic behaviour; they can become grumpy, unpredictable or just plain moody.

To explain this more fully we need to have an understanding of the hormones involved. A herbalist friend of ours compares the hormones within the body to an orchestra, each player has an individual job, but together they really make music. Although hormones are secreted by various glands throughout the body in very small amounts, they are extremely powerful in their actions.

The control centre of the hormones involved in breeding is the pineal gland, located in brain. Changes in light (usually day light in New Zealand, but in Europe they often use artificial light) cause a reduction in melatonin production. This allows secretion of GnRH (Gonadotropin Releasing Hormone) by the hypothalamus and in turn stimulates the production of FSH and LH (Follicle stimulating hormone and Luteinising hormone). See figure 1.

As we get into spring mares will start to cycle. This is called the oestrous cycle. Mares are normally seasonally polyoestrus....this means they will cycle many times at the right time of year..We must remember that the main purpose of a species is to reproduce. The most important start to this process is ovulation. This process is partially controlled by FSH and LH. As you can see from the diagram 2 LH levels peak at different times in the cycle. If these peaks get a little out of step then things can start to go wrong. Progesterone is also important in preventing a non pregnant mare from displaying signs of oestrus. As you would expect levels dip at the beginning of the oestrus phase. Fig 2.Hormone Cycles.

Moody Mares.

So what does all this mean? The typical moody mare syndrome is more evident than ever at the beginning of the breeding season. Mares are starting to cycle as the weather improves and if the hormone cycles are not quite as they should be this can be this can cause ill temper and other behavioural difficulties. These can vary from excessively long oestrus, over frequent oestrus and bad temper. This contrasts with mares where everything is in order. Cycles should be short..rarely exceeding 6 days and during oestrus the mare will often became very soft and cooperative.

How Herbs can Help.

Herbal medicine is well equipped to help with female reproductive disorders. After all nature abhors an empty uterus and will do all she can to fill it. There are books on the subject .

The most important herb we use is Chaste Berry (Vitex agnus-castus). It works in a number of ways including promotion of progesterone levels, decreasing FSH secretion and increasing LH and prolactin secretion. It has been in long traditional use in humans and we have found it just as useful in mares.

To get the best effects it is usually necessary to use Chaste Berry for a couple of months. It should be given each morning and administration is simple as the dose is quite low. The best form of the herb to use is a tincture. This ensures accurate dosing and ready absorption.

If you surf the net you will probably find mixtures of dry herbs containing Chaste. They will usually include a caution against use in pregnancy or lactation. As far as Chaste is concerned there is no evidence to support this caution. Indeed, Chaste is used to support.pregnancy in the first trimester and to help increase lactation. A trial in 1943 showed an increase in milk production in 80% of 125 subjects and one in 1957 showed that average milk production of three times that of the controls after 20 days treatment. These were both human studies. In early pregnancy Chaste has been shown to support the luteal function. This coincides with the first trimester.

Pregnancy is usually a trouble free and wonderful experience but if you are unsure talk to a qualified medical herbalist or your vet.

© James Hart