Apart from manifestations related to the cycle in mares and breeding-related aggression, a variety of behavior problems can occur in horses. Some of the most common are aggression (including aggression towards people), fear, performance problems (e.g., bucking), abnormal eating habits and undesirable stall behaviors.¹

Some potential causes of behavioral problems in horses can include:

• Gastric ulcers
• Soreness
• Conflict behaviors (inconsistent training methods and cues)
• Thermoregulation problems

Often, behavior problems in horses are a result of issues with confinement. Horses have evolved to spend more than half of their day foraging, with the remainder of their time being spent standing, lying down, grooming, or engaging in another activities. Since horses are social animals, they require contact with others for normal daily maintenance and well-being. Isolation—as is seen in many facilities—runs counter to normal equine behavior.

Behavior Problems in the Horse 

Aggression is a common problem in horses that can includes chasing, neck wrestling, kicks and bites, and other threats.¹Aggression toward people is usually seen in stalls, where the horse feels confined and can easily defend. Aggression toward other horses is usually associated with breeding, sexual competition, fear, dominance, and territory.²

Fears (phobias) can also arise in horses. While fear is a normal response to a real or perceived threat, phobias are exaggerated fear responses that are sudden, profound and result in panic. The two most common phobias in horses are associated with noise and location. Horses naturally have a fear of new things (neophobia), which may be responsible for some behavior issues, such as trailer-related problems.² These can include refusing to enter or leave the trailer and scrambling while traveling. 

Stall walking is a behavior wherein the horse will walk in circles around the stall. When released to a larger space, they continue to circle in a small area. Stress and anxiety appear to exacerbate this problem. 

Weaving occurs when a horse that normally stall walks is tied or prohibited from walking due to restricted space. Because they cannot circle as usual, they will still move constantly, but in a weaving motion.¹

Pawing or digging can cause injury to a horse, damage the stall floor, and cause wear to the horse’s hooves. It is a normal behavior when horses on winter pasture are forced to dig for feed. When horses are confined and fed highly palatable foods, pawing can occur more frequently and more intensely than it would otherwise.² Pawing can occur due to frustration, anticipation, or as a displacement behavior. 

Kicking the walls of the stall can damage a horse’s legs and stalls. A horse may kick due to boredom, aggression, or frustration. When it is due to aggression, kicking can occur when another horse is nearby or when the horse perceives that another horse is nearby.¹ Kicking can also occur when a horse anticipates being fed. Unfortunately, when the horse is then fed, the behavior is reinforced, leading to a repetition of the behavior. 

Cribbing (or wind sucking) involves a horse grasping a horizontal surface (such as a fence) with its front teeth, flexing its neck, and sucking air. It is more likely to occur in Thoroughbreds and other racehorses. Horses that crib have worn teeth and develop thick neck muscles. 

Self-mutilation occurs when a horse hurts itself by biting itself or kicking its abdomen with its hindlegs. This may be due to a medical problem, such as a digestive disorder (e.g., colic), skin disease, or pain. The veterinarian can help differentiate a medical problem from one that is primarily behavioral. 

Fluoxetine for Horses

The available literature holds that fluoxetine is a useful tool for the treatment of behavior-related problems in horses. It has been successfully prescribed to facilitate stall confinement and treat other behavioral problems, with 70% of owners reporting improvements in behavior with fluoxetine.⁴ Adverse effects in horses are uncommon and mild.

Where to buy Fluoxetine

Fluoxetine is available in the U.S. through several pharmaceutical manufacturers and through veterinary custom compounding companies. 

Fluoxetine carries numerous potential drug interactions. Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

¹Merck Veterinary Manual.

²equusmagazine.com.

⁴Fontenot, R. et. al. Retrospective Evaluation of Fluoxetine Hydrochloride Use in Horses: 95 Cases (2010–2019), Journal of Equine Veterinary Science, Volume 97, 2021, 103340, ISSN 0737-0806.