Mares get some pretty bad press. Many horse owners have a love or hate mentality when it comes to female equines. I’m firmly in the ‘love’ camp. I’ve owned three mares and feel my best partnerships have been with them compared to geldings.

With an estimated 300,000 mares in the UK* and 93%** of mares in general showing undesirable behaviour when in season, it’s easy to see why owning a mare can prove to be challenging to say the least. Where the behaviour is extreme it’s not unheard of for a mare to be asked to move to another yard, and situations like this can seriously hinder your enjoyment and ability to bond with your mare.

However, there are solutions, as discussed at Nettex’s Miracle Mare webinar in March. These need to combine behavioural and environmental management, and appropriate and effective nutrition and dietary supplementation. With a better understanding of what makes her tick and a more thoughtful management routine, you will see your opinion of mares change.

The oestrus cycle

Normal life for a mare in the wild is very different compared to our domesticated mares, but they have one thing in common: as a mare, the biological intention is for her to become a parent.
Most of us won’t breed from our mare, so this means she doesn’t get that natural outlet for her hormonally-driven reproductive behaviour, and this is why frustration and changes in behaviour are likely every 21 days.

  • A mare reaches sexual maturity at 18 months old and will continue to cycle throughout her lifetime.
  • As spring arrives and daylight hours increase, mares will start their oestrus cycle again and have regular cycles throughout the summer months.
  • During the winter, when mares aren’t normally in season, they are said to be in anoestrus.
  • The normal oestrus cycle lasts for 21/22 days and during this time she will have four to seven days when she is most receptive to a stallion for breeding, with ovulation usually occurring on about day five of the cycle.
  • If the egg is not fertilised, the mare will move into the dioestrus phase, which lasts for between 13 and 17 days. This is when the hormone progesterone is dominant and then her cycle starts again.

Why behaviour changes

It’s the changes in behaviour when a mare is in season that gives them a bad name and for some makes them undesirable, but it’s important to remember that she is merely exhibiting natural behaviours. She’s not behaving badly or wilfully — it’s almost beyond her control. So rather than referring to them as ‘bad behaviours’, changing the terminology we use to ‘undesirable behaviour’ is better.

Essentially, it’s the different hormones that cause a change in her behaviour, as she switches from progesterone being the dominant hormone to oestrogen being dominant. Breaking down the common behaviours we see into two categories is useful.

1 Mare-specific behaviour

These are behaviours that are only really displayed by a mare in season, such as:

  • Winking
  • Squirting
  • Raising her tail
  • Squealing
  • Frequent urination
  • Repetitive vocalisation

2 Non mare-specific behaviour

This is any aggressive type of behaviour, such as biting, kicking, bucking and grumpiness, as well as difficulty tacking up, lack of concentration, poor performance and stereotypical behaviours such as weaving.

While a seasonal mare may show these behaviours, these are classed as non mare-specific as they could be displayed by any horse that has other underlying conditions and could be pain related.

Sometimes there is a genuine physical abnormality that explains her behaviour and if you are concerned you should seek your vet’s advice.

The impact of these behaviours

These undesirable behaviours can cause significant problems for owners, having an impact on your safety and the safety of other horses. Sometimes a mare can even cause damage to herself.

How this behaviour is dealt with can have further implications. For example, you may find that during her season it disrupts the usual yard routine as you find yourself trying to avoid contact with other horse owners or vice versa.

It can also end up with mares being turned out on their own to avoid any possible injury to other horses or to themselves exacerbating the problem further. A drop in performance when competing can be common too – a mare showing undesirable behaviour is unlikely to be able to perform to the best of her ability.

Consider her feelings

Having a better understanding of the behaviour of wild horses will help us improve our knowledge and handling of domesticated mares as Jenni Nellist, clinical animal behaviourist, explains.

“When a mare isn’t in season, she will usually reject any sexual approach from the stallion. This is done mostly by walking away and often they are happy to mutually groom with him. Once she starts to come in to season, she’ll feel more conflicted — not quite ready for courtship but she’s attracting more attention from the stallion and her behaviour reflects this.

“On the one hand she may welcome his approach but then very quickly change her mind and can quite forcefully reject his advances,” continues Jenny. “Feeling irritable is typical of mares approaching the most receptive time of her cycle because they are conflicted between seeking and avoiding that courtship.”

It’s during this phase that we need to think about what we expect our mares to tolerate from us and why during her oestrus cycle she may display a change in behaviour. For example, we brush her on a daily basis. Being irritable and not wanting to be touched is one of the behaviours commonly seen, yet we still expect her to let us brush her.

We also ride her and compete in the company of both familiar and unfamiliar horses, and there are times during her cycle when she will find this difficult. When you stop to think about how she may be feeling, you can’t help but think we’re looking for trouble.

Mostly this behaviour is natural, if somewhat frustrating for the owner and also more importantly, for the horse, when at times her lifestyle makes her seasons feel more challenging to her.

References: *British Equestrian Trade Association’s National Equestrian Survey 2019 **1.Mills, D and Nankervis, K. 1999. Equine Behaviour: Principles & Practice. Blackwell Science Ltd. (p144) 2.Waring, G.H. 1983. Horse Behaviour: The behavioural traits and adaptations of domestic and wild horses, including ponies. Noyes Publications, Park Ridge, New Jersey

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