If you’ve ever ridden a mare, you’ve heard the phrase — sometimes from yourself, sometimes from someone watching you struggle around a warm-up ring: “Oh, she’s just being marish.”
And sometimes that’s true. But sometimes it isn’t, and the difference matters enormously. A mare who’s genuinely in pain does not need more pressure, a firmer leg, or a different training approach. She needs a vet. The problem is that the behavioral presentation of normal hormonal moodiness and actual ovarian pathology can look almost identical from the saddle — and getting it wrong costs you months of training, your horse’s trust, and in some cases, her soundness.
Let’s break down what you’re actually looking at.
What “Normal” Mare Behavior Actually Looks Like
Mares cycle roughly every 21 days, with estrus (heat) lasting approximately 5-7 days. During that window, progesterone drops and estrogen rises. The result, in a lot of mares, is a horse who is more reactive, less tolerant of leg aids, tighter through the back, and generally less interested in cooperating.
This is normal. It’s not ideal for competition, but it’s within the range of expected.
Behavioral signs of a typical hormonal cycle:
- Increased sensitivity to leg or girth contact during estrus only
- Tail wringing when the leg is applied — more than usual, not constant
- Ears pinned when another horse passes or when you first mount
- Mild resistance to bending toward the dominant ovary side
- Squirting or presenting to other horses
- General crankiness that resolves within a week
The key word in all of that is cyclical. Normal mare behavior follows a pattern. It appears, it peaks, it resolves. You can often track it on a calendar once you know your mare. Many riders do exactly that — they note the grouchy weeks, plan lighter sessions or trail rides during estrus, and schedule their big training pushes around the more cooperative phases.
That’s a management strategy, not a training failure. And it works fine for mares whose moods are hormonally driven rather than pain-driven.
What Ovarian Pain Actually Looks Like
This is where it gets harder to sort out, because the signs overlap significantly. But there are specific patterns that should raise your index of suspicion.
The pain is not cyclical — it’s constant or worsening
If your mare is difficult throughout the month, not just during estrus, that’s a flag. Normal hormonal moodiness has a rhythm. Pain doesn’t follow one.
The resistance is asymmetrical and specific
A mare with an ovarian cyst or granulosa cell tumor (GCT) will often show asymmetrical resistance that’s tied to a particular side. You’ll feel it as a block — she’ll bend left without much complaint, but tracking right she’s stiff, resistant to your right leg, and falls heavily to the outside. Or vice versa. This isn’t the general crankiness of a mare in heat. This is a structural response to something that hurts on one side.
Where the ovaries sit matters here. The ovaries are positioned just behind and below the last rib, left and right. A horse with a mass or cyst on the right ovary may resist right-leg aids, resist bending right, or show sensitivity when you press firmly just behind the last rib on the right flank. That flank sensitivity test isn’t diagnostic, but it’s a useful starting point for your conversation with the vet.
She reacts to palpation, not just to aids
If your mare pins her ears and swings her head when you press on her flank — not just when you use your leg, but when you use your hand — that’s meaningful. Normal hormonal mares are annoyed by aids. A mare in ovarian pain is often reactive to direct pressure on the flank regardless of context.
Performance doesn’t improve with correct training
This is the clinical one. If you’ve ruled out saddle fit, back pain, ulcers, and hock issues, and your mare is still resistant in a consistent pattern regardless of where she is in her cycle, the ovaries need to be on the list. I’ve seen mares labeled as difficult, dangerous, or unrideable who turned out to have significant granulosa cell tumors. The moment the tumor was removed, they were completely different horses.
That’s not a training problem. That was pain.
The behavioral changes came on relatively suddenly
This matters. A mare who has always been “mareish” is different from a mare who was easy to ride for three years and then changed. A shift in behavior is always a clinical sign until proven otherwise.
The Most Common Ovarian Pathologies to Know About
Granulosa Cell Tumor (GCT)
The most common ovarian tumor in mares. These are usually benign but can grow large — sometimes basketball-sized — and significantly disrupt hormonal balance. A mare with a GCT often becomes anestrus (she stops cycling) or shows persistent stallion-like behavior because the tumor produces testosterone. She may become aggressive, mount other horses, or be extremely difficult to handle.
Diagnosis is via rectal palpation, ultrasound, and hormone panels. Treatment is surgical removal of the affected ovary, and most mares return to normal cycles and behavior within a year.
Ovarian Cysts
More common and less dramatic than GCTs. Follicular cysts can be persistent, produce hormonal disruption, and cause chronic discomfort. A mare with a large persistent cyst may show ongoing low-grade pain signs — reluctance to work, sensitivity through the back, inconsistent response to aids — without the stallion-like behavior of a GCT.
Hematomas
Post-ovulation hematomas can form within the ovary and are often self-resolving, but large ones can cause acute discomfort that looks like colic. If your mare has a sudden episode of pain, flank sensitivity, and reluctance to move normally — particularly in the days following a known ovulation — hematoma is worth discussing with your vet.
How to Have a Useful Conversation With Your Vet
Come prepared with documentation. “She’s been hard to ride” is not enough information. What you want to bring:
- A calendar of her cycles, if you’ve been tracking them, with notes on behavior each week
- Specific behavioral descriptions: which direction is harder, what aids provoke the reaction, whether it’s consistent or cyclical
- A list of what you’ve already ruled out (saddle fit, ulcers, hocks, back)
- Whether the behavior is new or longstanding
Your vet will likely start with a rectal exam and transrectal ultrasound to assess the ovaries directly. If there’s a question about hormonal involvement, they’ll pull bloodwork for inhibin, testosterone, and progesterone levels. That panel is usually enough to identify a GCT even before imaging confirms the size.
What to Do in the Meantime
If you suspect something is off but you’re waiting on a vet appointment, the answer is not more training pressure. Drop your expectations for the session, ride quietly, and take notes on what you observe.
Some riders use Regu-Mate (altrenogest) under veterinary supervision to suppress the cycle in mares with hormonal behavioral issues. It can be genuinely useful for competition management in mares with exaggerated but normal estrus behavior. It will not fix a GCT, and it is not a diagnostic tool — if the Regu-Mate doesn’t help at all, that’s information.
Compounded progesterone products and herbal cycle supplements are also widely used in the mare management world. I’ve talked through my own experiences with this on The Elevated Equestrian podcast — the short version is that results vary significantly by mare, and none of them replace a proper veterinary workup when you’re genuinely concerned.
For mares who do have documented hormonal cycles that disrupt training, there’s a reasonable management conversation to be had around supportive care: quality magnesium supplementation, targeted bodywork during the hard weeks, and strategic scheduling. If you’re shopping for supportive wraps or therapeutic products for recovery around hormonal cycles — particularly for mares who carry tension through the back — I’ve reviewed several options over in the gear reviews section of the site that are worth a look.
The Bottom Line
Mares are not just difficult horses. They are horses with a hormonal cycle that can meaningfully affect their comfort and behavior — and occasionally, they are horses in real pain that looks, on the surface, like a training problem.
The distinction:
- Normal hormonal moodiness is cyclical, manageable, and resolves on its own
- Ovarian pain is often asymmetrical, constant or progressive, and does not improve with training alone
If you’ve been riding the same mare for a year and she has a predictable grouchy week every three weeks, she’s probably just a mare. If she changed, if she’s consistently resistant on one side, if her behavior doesn’t follow a pattern, if she reacts to flank palpation — get the ultrasound. It’s not expensive relative to months of confused training and a horse who’s suffering.
Give your mare the benefit of the doubt. She’s telling you something. The question is whether you’re listening carefully enough to know what it is.
