Why Is My Horse Acting Irritable?

Emma Hardy, PhD answers a reader question.

Credit: Identifying a digestive disorder at an early point is crucial to our horse’s welfare as it enables the most effective treatments to be selected and can shorten recovery times. Overt signs can include sensitivity to brushing or girthyness.

Q: My Second Level dressage horse, a 12-year-old Dutch Warmblood mare, has recently been acting irritable when under saddle. It’s not consistent, but when it happens, she becomes reluctant to move off my leg and will sometimes kick out. I’ve had the saddle fitter out and everything seems to fit fine. I’m wondering if she might have ulcers. Are there other signs that can help pinpoint why she might be acting out?
Name withheld by request

Emma Hardy, PhD

A: Regularity of paces, freedom of movement, responsiveness and willingness, balance and impulsion—these are attributes we all strive for in our dressage horses and are the basis of all development and progression in the arena. However, where do we turn when one or more of these are proving elusive despite correct and appropriate training? Perhaps our horse is struggling to extend and collect, is reluctant to accept the leg aids or frequently tail swishes, is finding it difficult to flex over the back, engage the hindquarters or shows negative changes in temperament. 

A horse might also be reluctant to bend through his body, particularly to the right. Post mortem studies have found that the right dorsal colon is frequently the site for inflammation and ulceration. Because of the colon’s anatomical location within the horse, pain, sensitivity and discomfort arising from an abnormality in the mucosal pathology can elicit the types of symptoms stated.

We could be seeing just one or two of these behaviors or all and more. Maybe it’s a subtle change noticed by a sensitive rider or something more overt (enter arena at A, deposit rider at X). Regardless, the frustration of this scenario is the difficulty in pinpointing its cause. Without this, finding an effective resolution can be lengthy, expensive and sometimes heartbreaking.

First of all, we must consider that instead of thinking our horse won’t do something, maybe it’s that he can’t. So we book the saddler, physiotherapist and dentist. If nothing significant is identified, where this then leads can be limitless. Investigations carried out by veterinary professionals, associated professionals and alternative or complementary therapists may still lead to dead ends. However, an area that is frequently overlooked when trying to resolve training difficulties, but is implicated more often than you might expect, is the equine digestive system.

Identifying a digestive disorder at an early point is crucial for many reasons. It benefits our horse’s welfare as it enables the most effective treatments to be selected and can shorten recovery times. It is also worth remembering that the digestive tract is the fuel line for all the other biological systems. Overt signs, such as loss of condition, looking tucked up, dull coat, weight loss and poor feed absorption, may all be red flags for a hindgut disturbance. The discomfort that may accompany this can manifest in sensitivity of the flanks (dislike to brushing, rugging, pressure), girthyness (frequently mistaken for gastric discomfort) and even colic-like symptoms. 

Over recent years much research has been directed toward the causes, management and drug development for gastric ulceration, but comparatively little attention has been afforded to digestive disorders beyond the stomach. Recent research shows that these types of issues are surprisingly prevalent among our competition horses and that diagnosis can be confused, delayed or, at worst, even missed altogether. 

So why are we missing hindgut problems? When it comes to medical conditions of the horse’s hindgut, diagnostic techniques available to veterinarians are limited. No endoscope can safely visualize the hindgut, so our veterinarians are left with interpreting blood and biopsy results, evaluating ultrasound images, clinical signs and symptoms in order to reach a diagnosis. Furthermore, some digestive disorders can look like others, which only compounds an already difficult task. Treatment strategies are then commenced with definitive diagnosis later confirmed (or not) by their success. 

Optimizing digestive-tract health starts with understanding the horse’s system. Horses are hindgut fermenters, evolved to life of low stress and a trickle-fed fiber diet. This picture seldom reflects the management and feeding regimens we need to implement for peak performance, so it’s little wonder digestive-tract disturbances occur. The equine hindgut is a vast structure, designed to support bacterial fermentation of large volumes of fiber and is responsible for producing upwards of 70 percent of the horse’s energy. As a result, the health of the hindgut is paramount. 

If we can aim to feed and manage the horse as he has evolved to do, we can reduce the risk of digestive issues. Free access to forage meets behavioral needs but also helps to buffer the stomach’s continuous secretion of gastric acid. It is already well established that an empty stomach is implicated in the development of gastric ulcers. 

The horse has a limited capacity to digest starches and sugars, particularly when delivered intermittently and in large volumes. This type of diet and feeding is a perfect combination for overloading the hindgut with poorly digested feed. The subsequent bacterial inversion drives acidity in the hindgut, and further proliferation of pathogenic bacteria. Endotoxemia, colic, laminitis, colitis and ulceration are all possible outcomes, but by limiting starch and sugar and providing smaller, more frequent meals you can help to avoid this. Increasing turnout may also help limit stress and promote the horse’s natural behavior, which are all beneficial to digestive-tract health.

Nutritional support directed to the structure and function of the digestive tract may be useful particularly during training, traveling and competing. This not only helps
the horse to cope and even thrive in the face of today’s feeding and management regimens but also helps to maximize feed absorption.

As owners, riders and trainers, we have a responsibility to our horses and their welfare. Education, empathy and sometimes a little lateral thinking should be our aim when our horses seem to be telling us that something isn’t right. Peak performance starts from the inside out and is only truly compatible with a healthy, happy horse.

Emma Hardy, PhD, has been the European marketing manager for Freedom Health LLC since joining the company in 2009. She holds a PhD in equine science from the University of Lincoln, UK, and is a member of the British Society of Animal Scientists.







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