Sure, mares have hormone level swings just like human females, but a sudden change in temperament—whether in a mare or a gelding—could signal an underlying health problem.

Sure, horses have good and bad days. But pinning ears, threatening to kick or bite or other unusual aggressive behavior could be a sign that your horse is in discomfort. To determine what’s causing the behavior, horse owners need to put on their sleuthing hats and start turning over clues.

1. Has there been a change in the horse’s workload? Is he being asked to use muscles more intensely or in a different way than before?
   
   
2. Examine him from ear to tail: perhaps he has a bruise or a gall that’s causing him pain.
   
   
3. Is the behavior only at certain times of the day or during certain kinds of activities, such as riding, turning him out or bringing him in?
   
   
4. Take his vital signs. Are pulse, respiration and temperature normal?
   
   
5. Check his saddle fit. If you don’t know how to tell if your saddle is working with your horse’s anatomy, bring in an expert.

If you don’t uncover anything and his behavior persists, bring in your veterinarian to help. It could be a bad tooth, a sore back or some other cause a professional can help solve.