May 5, 2026, 2:58 pm | Read time: 5 minutes
“She’s just in heat”–a phrase often heard, especially when mares are considered moody or “bitchy.” But is that really true? In an interview with PETBOOK, behavioral biologist Dr. Vivian Gabor explains when behavior is normal or if there might be more behind it.
Are behavioral changes during heat normal or often a sign of pain?
Slight behavioral changes are completely normal in connection with heat, explains Dr. Vivian Gabor: “Some mares are more affectionate, sensitive, easily distracted, or react more strongly to other horses.”
At the same time, the expert emphasizes: “However, if a mare shows clear defensive behavior, strong irritability, problems with grooming, saddling, or riding, recurring performance drops, or noticeable sensitivity in the flank, belly, or back area, it should not be hastily dismissed as ‘typical mare behavior.'”
If this is the case, a closer look is always worthwhile, as such changes could also be due to pain or other physical causes, the behavioral biologist further explains.1
“More calm, clear signals, less conflict pressure”
Especially riding beginners often wonder: How do I best handle a mare in heat? “The most important things are observation, flexibility, and fairness,” explains Dr. Vivian Gabor. The expert further elaborates that one should take the mare’s behavior seriously and adjust the training to her daily condition instead of working against her.
“In sensitive phases, more calm, clear signals, less conflict pressure, and an overall well-structured, low-stress environment often help,” advises Dr. Gabor. Additionally, it’s not about simply accepting behavior but understanding the cause and sensibly adjusting the demands, the expert emphasizes.2
Is heat a burden for the mare?
Whether heat is actually a burden for the mare varies greatly from individual to individual. The behavioral biologist assesses it as follows: “For many mares, heat is not a major problem, but for others, it can be associated with significant discomfort. Therefore, one should neither dramatize nor trivialize.”
It is crucial to consider the individual animal, emphasizes Dr. Gabor: “How much do behavior, movement quality, responsiveness, and well-being change? A mare that regularly appears significantly impaired should be taken seriously and, if necessary, examined by a veterinarian.”
Why individual mares react so differently to heat is explained by the equine scientist as follows: “Mares are individuals. Differences can be related to temperament, past experiences, pain perception, health status, living conditions, training load, and social environment.”
She further explains: “Additionally, horses generally react very differently to internal and external stimuli.” Therefore, it is scientifically not very meaningful to speak of “the typical mare.”
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What role do living conditions, training, and feeding play in mares in heat?
According to the behavior expert, living conditions, training, and feeding play a very large role. “Living conditions and management influence the general stress level and thus how well a horse copes with physical or hormonal changes,” explains Dr. Gabor. Social contact, exercise, appropriate feeding, sufficient roughage supply, good sleep, and a reliable daily routine are important factors.
But not only that, training also plays a role: “A horse that is constantly overwhelmed, misunderstood, or worked in pain will be more noticeable in sensitive phases.” Heat is often not the actual cause. It is rather the moment when existing problems become more visible.
Why are mares often labeled as “difficult” compared to geldings?
From the expert’s perspective, many attributions and old stereotypes play a role here. “With mares, behavior is more quickly personalized or emotionally evaluated, while with geldings, one speaks more of ‘daily condition’ or ‘misunderstandings.'”
This is problematic because legitimate indications of discomfort, pain, or overload are easily overlooked. In this context, the behavioral biologist emphasizes: “The term ‘bitchy’ is therefore not only imprecise but often also unfair because it devalues behavior instead of questioning the causes.”3
Moreover, one thing is particularly important to the behavioral biologist: “Heat should not serve as a convenient explanation for every undesirable behavior.” If a mare is regularly noticeable, one should always look at the overall picture–health, saddle, teeth, feeding, training, living conditions, and social situation, says Dr. Gabor. Often, heat is not the problem itself. It merely reveals that there is already a burden somewhere.
The expert’s conclusion is accordingly: “Mares in heat are not generally ‘difficult,’ but often just more sensitive in a certain phase. That’s exactly why it’s worth looking closely instead of judging. Those who view behavior in a differentiated way not only protect the mare’s well-being but usually also improve cooperation with her.”