Q&A: The Moody Mare - Is There Any Truth to the Stereotype?

“Owners often say my mare is difficult when in season or my mare is always in season and is therefore difficult. This does not fit with the behaviours which are shown by a mare in season.”

Q:

Is there any scientific evidence to support the idea that mares are more moody [temperamental, subject to changes in their state of mind, manifest by alterations in behaviour] than male horses? 

A:

The simple answer is no.  There are many signs attributed by owners to moodiness in mares, caused by being in season, which include aggression, anxiety or nervousness, sensitivity around the flanks or girth region, being difficult to handle, ears back, resistant, repeated tail swishing, excessive urination, kicking and generalised decrease in performance. However, these are not generally the signs demonstrated by a mare in season. 

During the summer months mares cycle every 3 weeks and are in oestrus for a few days. During those few days a mare may show clitoral winking, frequent urination, squatting (dropping the hips – which would facilitate mounting by a stallion), elevation of the tail, and in the presence of male horses, especially a stallion, may turn the head and neck towards the tail (a signal to a stallion of receptivity). In the presence of a stallion a mare in season usually has her ears forwards and her overall attitude is one of tolerance.  When ridden when in season a mare may show reduced sensitivity to leg cues, reflecting her tolerance, but does not show signs of resistance; in contrast in the previous few days a mare may be slightly more sensitive to tacking-up and rein pressure.

Owners often say my mare is difficult when in season or my mare is always in season and is therefore difficult. This does not fit with the behaviours which are shown by a mare in season. If behavioural signs were attributable to a mare being in season, they would not be present during the winter months, and would be present for only a few days every 3 weeks during the summer months. Owners tend to attribute behaviours to a mare being in oestrus which are not consistent with the actual signs of being in season.  The actual signs exhibited by the mare are important to describe and interpret correctly.

When an owner says my mare is always in season it is useful to keep a diary of what behaviours are exhibited when. We can then ask whether or not those signs are compatible with oestrus, in terms of how frequently oestrus occurs and the signs associated with being in season. How does the mare interact with field companions? Signs of aggression, anxiety, ears being back, resistances are not consistent with the signs shown by a mare in season. A mare in season has her ears forwards, is quiet and acceptant of other horses and may choose to interact more with male horses than when not in season.

Oestrus can be suppressed by administration of a synthetic progesterone, altrenogest, marketed as Regumate®. There is always the possibility of a placebo effect – an owner expects to see a change in a horse’s behaviour.  It is therefore useful to keep a diary of the horse’s daily performance and behaviour before and during treatment.  If a mare’s behaviour genuinely improves then continued treatment with Regumate may be indicated, but if the majority of behavioural signs persist then we need to look for alternative causes of those behaviours. The most common underlying cause is musculoskeletal discomfort.  

© Sue Dyson 2023