Equine Science Sundays: The 'Misbehaving' Sport Horse

"What bit should I use for a horse who...."

"My horse spooks SO MUCH! What calming supplement is strongest?"

"He's just so lazy undersaddle, what spurs should I try?"

These are all commonly overheard questions, that all lead back to a theme of "why is my horse not behaving the way I want them to undersaddle?" A recent review article, written by Dr. Erin Contino, a lameness and performance vet from Colorado State University, questioned whether performance horses are ever "misbehaving".

Dr. Contino reports "there is a subset [of horses] that do not present for overt lameness, but rather present for some form of performance or behavioural issue. Although time-consuming, determining and addressing the underlying cause is of utmost importance from a horse welfare standpoint".

Previous studies have established:

• 116 horses who were presenting poor performance all had lameness in at least 1 leg.

• Riders underestimate lameness, with horse owners only recognizing a sound horse 54% of the time. That means that just under half of the horses who were thought to be sound were in fact not.

The review article continued to explain several issues that present as performance issues such as increased spookiness, reduced gait quality, inconsistent rein contact, evasiveness when asked to perform certain movements, and decreased hindquarter push, instead of obvious lameness. Common issues that present as 'behaviour issues' include sacroiliac joint pain and hindlimb suspensory issues.

"Behavioural issues are actually a manifestation of an underlying physical or physiologic problem."

One of the most common causes of pain-related behavioural issues was reported to be axial skeletal issues. The axial skeleton includes the skull, vertebrae, ribs and sternum. Some cases have spinal nerve issues and "wind up pain", where the body begins to interpret even gentle sensations as pain, which manifests as "bad behaviour" as the horse responds to pain that they cannot understand or control.

Other causes of poor performance that aren't your horse "being bad" or "feeling lazy" include:

• Hoof pain: Pain in the front hooves can present with a stabbing forelimb gait (where the horse's toe touches the ground first), refusing at fences uncharacteristically, and can become unsteady in rein contact.

• Muscle diseases (PSSM, RER, MFM) may present as a reluctance to move forward, back pain, lack of proper form over fences, undiagnosed lameness, and reluctance to collect.

• Respiratory issues may present as being "lazy" due to exercise intolerance (ie, they cannot get enough oxygen to perform), or resisting flexion (harder to breathe).

• Digestive compromise: Ulcers can contribute to girthy behaviour and stress under saddle. Horses with hindgut issues are reported to be more reactive and spooky.

A note on ulcers: Undesirable behaviour under saddle is often automatically considered to be due to ulcers, resulting in treatment for ulcers. However, since ulcers can develop due to the stress of pain, this alone may not resolve the root cause of the horse's discomfort, so exploring several routes of the root pain is recommended.

Dr. Contino also elaborates that for horses who appear sound in-hand, an undersaddle examination can help observe the horse in different scenarios, which is useful for identifying contributing factors. Saddle slipping? This is highly correlated with slipping towards a hind limb lameness. "Grumpy" behaviour during tacking up or mounting? This is associated with a higher likelihood of lameness, epaxial muscle pain or saddle fit issues.

"Many "behavioural issues" resolve when the underlying problem is diagnosed and treated".

As horse-first equine caretakers, it is our responsibility to use behaviour as information rather than taking it at face value. While lameness and pain are the most common causes, other issues can stem from hormones, digestive compromise, impaired respiratory function and muscles disorders. It is also important to consider your horse's species-appropriate needs and environment to rule out behaviour "issues" from unmet species-speciifc requirements, such as chew time, fiber requirement and turnout with suitable social companions.

Work with your horse's vet team if your horse is exhibiting signs of poor performance, and consulting with an equine nutritionist and clinical behaviourist can help you and your horse move forward once the underlying root cause has been addressed.

References & Further Reading

Contino, EK. 2025. The "misbehaving" performance horse: is it ever behavioural? Journal of Equine Veterinary Science 148(2025): 105420.