Studying the feed behavior of horses in training - why we keep on losing the battle with ulcers?

Keeping a racehorse healthy inside and out can be a real challenge. The nature of training and the environment in which racehorses live presents a constant set of risks. Managing those risks and balancing them against what is needed to achieve success is a fine art. 

So where does risk come from when it comes to digestive function? Are those risks manageable within the racing environment? What can you realistically expect to achieve with changes to feed, feeding practice and the use of supplements?

One of the biggest risk factors for digestive health is the stabled environment and the pattern of feeding required to fit in around a typical working day for stable staff, coupled with the need to get out on the gallops. On top of this is then the individual’s feeding behavior, something that can easily be overlooked when the ‘what is fed’ is the same for all horses in the barn. Individual behavior is perhaps one of the hardest aspects to tackle, whilst replicating a natural feeding pattern is nearly impossible.

The most common digestive concern is gastric ulcers, and many feeds and supplements are now available and marketed for this condition. Yet ulcers still exist and continue to frustrate many trainers despite making dietary changes. Why is this? The answer lies in gaining a better understanding of what a ‘good’ feed pattern and diet looks like from the horses’ perspective versus what is effective for performance and realistic in a typical racing stable. 

What is a natural feeding pattern?

Free ranging horses typically show 10-15 distinct feeding bouts in a 24-hour period (1).

Time spent resting or engaged in other non-feeding activities will not normally exceed 3-4 hours per session (2). Meaning the stomach is rarely truly empty.

The majority of feeding behavior happens during daylight hours, typically 60-70% of time available (3).

During nighttime hours the amount of time spent as feeding behaviors reduces to 40-50% of those hours (3).

The total amount of time spent grazing across multiple feeding bouts is connected to the season and daylight hours. During summer months intake is around 14 hours in total versus 12 hours in the winter (4).

The natural feeding pattern is driven by the design of the horses’ digestive anatomy and is key to good health and normal function. The further away from these patterns we move any horse the greater the risk of dysfunction. 

What is a typical feeding pattern for a horse in training? 

The time study above shows the time taken for a group of 5 horses in training to eat their bucket feed and forage allocations in a 24-hour period. All horses in this observational study were in full training and worked in the morning of the study at different time points depending on their lot. Horses were observed from 4:45 am until 9:15 pm.  

One of the key aspects of natural feeding behavior is the amount of feeding periods or ‘mini-meals’ a horse consumes. For 4 out of the 5 horses from completion of their evening forage to the next meal of breakfast was a period of time in excess of 8 hours, approximately 33% of the 24-hour period. During these nighttime hours feeding behavior normally occurs in free ranging horses and supports regulation of the digestive system. 

For wild horses the total time spent eating is 12-14 hours in a 24 hour period. They do not normally have periods exceeding 12 hours in every 24 without some form of intake. For 4 out of the 5 horses there were distinct periods where all feed and forage had been consumed. The amount of time without any feed or forage available for the horses ranged from as little as 3 hours and 40 minutes up to 15 hours 30 mins in a 24-hour period.

Natural feeding patterns rarely see more than a 3-4 hour gap between each ‘mini-meal’ and at these points where gaps exist, it is important to remember that food has been available for 24 hours without restriction leading up to these chosen breaks in forage intake. The break in intake is short and during this time the stomach is unlikely to be truly empty. For horses in training it is easy to have periods in excess of 3 hours without any intake of feed or forage. 

Although the period from finishing breakfast to morning forage being given was for some horses less than 3 hours, the stomach when receiving that breakfast was in a fasting state. Ordinarily in the natural environment the stomach is rarely truly empty as it can take anywhere from 2-6 hours for the stomach to empty depending on what and how much has been consumed (5). When giving a bucket feed to a horse in a fasting state the rate of transit of that feed through the stomach will be relatively short, and depending on which lot the horse is pulled out for, can result in the horse being worked on an empty or near empty stomach. 

Why does this matter? 

One of the common causes of squamous ulceration is ‘acid splashback’ which relates to strenuous exercise and the movement of acidic content from the lower glandular region of the stomach to the unprotected squamous area (6). When the stomach contains feed or forage it is more difficult for the acidic content to be forced upwards to the squamous area. This is why it is recommended to include chaff in the breakfast feed or provide a small amount of forage as these fibrous sources are slower to pass through the stomach and can help reduce the level of acidity seen in the proximal portion of the stomach. The key point here is reduction not elimination. The practice will not prevent ulceration occurring, but it will reduce exposure.

The table below shows the difference between horses that were fasted for only 2 hours before exercise and those fasted for 18 hours. 

One of the challenges in racing is the differing amount of time between the breakfast feed and being saddled up for work. On top of this some horses will naturally consume their allocated feed faster. Even within the small number of horses observed in the study in Figure 1 there was notable variation in the time taken to eat the same amount of bucket feed given. Some of this variation comes from giving all horses the same breakfast by weight, which represents a different meal size against their bodyweight. Variation also exists as racehorses are individuals and appetite is flexible and influenced by other factors such as level of fitness and stress.  

Figure 3 shows the amount of dry matter provided in the breakfast feed to each horse and considers it against the bodyweight of the individual horse. The breakfast given was 4.85lbs / 2.2kg of a cubed racing feed alongside 1.3lbs / 0.6kg of an alfalfa based chaff. 

Can feed intake be slowed down?

In terms of feed format, pelleted feeds are consumed faster than mueslis or ‘sweet feeds’ (7). The addition of chaff mixed with the feed can slow intake, but for it to be effective there must be a reasonable amount given compared to the amount of pelleted or textured feed. As a rough guide, providing an additional 30% of the hard feed weight as a chaff will make a notable difference to the rate of intake. 

Whilst the aim is to slow intake it is important to keep in mind that feeding hard feeds too close to strenuous exercise is not recommended. Ideally feed is withheld for 2 hours before exercise. Forages, eg hay, haylage and alfalfa chaff, do not need to be removed but intake should be restricted to a small amount, typically 1kg. Providing a small amount of forage in this format helps maintain saliva production, which assists with regulation of acidity, and provides some fill for the stomach. 

Does forage intake matter?

Risk factors for gastric ulceration and colic when it comes to forage are similar. Diets low in forage and high in concentrates increase risk, along with intermittent feeding patterns and/or periods of fasting. 

In addition to what is given and the pattern that fits practically at a yard, is the fact that horses, like many other species, do not have a fixed rate of intake when a meal of any sort is presented. The majority will have a higher consumption rate at the start of feeding than at the end. With the observed horses hourly weigh backs of forage were carried out for a period of 6 hours to determine rate of consumption. During this time no bucket feed was present.  Figure 4 shows the individual intakes.

In the case of horses in training this is another problem to consider when it comes to evening feeds. Whilst the amount of forage given may be reasonable and in line with expected appetite, the feeding behavior of the horse means there is not a consistent or regular intake of forage observed until the following morning feed.  True feeding of ad-lib forage, above what a horse needs or could eat in a 24-hour period, is rarely given and often impractical. The reality is that most horses in training will have a prolonged period of zero feed or forage intake during nighttime hours, which is the opposite of natural feeding behavior. 

This is a practical challenge which for many yards is not easily overcome. Ideally forage should be fed at more regular intervals, rather than twice daily, to more closely replicate the 10-15 feeding bouts observed in wild horses. 

What can be done to improve feed patterns?

Simply put the longer a horse spends eating the better. 

An enthusiastic eater that is ‘keen at the pot’ might be taken as a sign of good health, but a speedy intake that leads to a feeding pattern with longer periods between any sort of meal isn’t necessarily a good thing. A horse that appears a little slow with their forage but still consumes a good amount over a daily basis is not a bad thing as the pattern of eating is closer to multiple mini meals. 

• Using a good amount of chaff in every feed will prolong feed intake and requires additional chewing which helps increase salivation. 

• In the case of morning feeds ideally a little hay or haylage could be given, particularly for later lots to ensure the presence of some fiber in the stomach when working. Such a presence will not completely stop acidity in the delicate squamous area of the stomach, but it will reduce it. 

• Providing the evening forage as late as is possible to reduce the amount of time between evening forage being consumed and breakfast given. 

• Taking note of ‘speedy eaters’ and considering if hay nets or hay feeders would be appropriate to prolong the time taken to consume their evening allocation. Hay nets in different locations in the stable, for example one at the front and one at the back, can also influence how quickly all the forage is consumed. 

• Consider the type of forage given. Hay can be easier to provide on more of a free choice basis as horses will consume less hay than haylage on a dry matter basis in a set period of time (1).

What is a realistic expectation for managing digestive health?

The need for high energy intakes to fuel performance means reliance on hard feeds and a limited amount of forage. The horse does not have an unlimited appetite and even when provided with additional forage will not necessarily consume enough or consume it in a regular fashion. Replicating a natural feed pattern for horses in training is close to impossible and inevitably results in digestive disorders, but making changes and trying to reduce that risk is worth doing. The differences made may be small, but winning margins can be just as small.

The purpose of feeding low starch diets to horses in training is to reduce the specific element of risk that comes from high starch feeding. In doing so that element of risk is managed and the diet is one step closer to a more natural fiber-based diet. But it is one area of risk alone and mitigating this risk does nothing to control the risk of ulcers or colic from intermittent feeding, the impact of withholding water,  the effect of travel and the physical effects on the stomach from strenuous exercise in the case of ulcers.

Using supplements that support healing of tissues, the function of mucus barriers or buffer acidity in the stomach are all part of trying to manage gastric ulcers, a disorder that is created through the training environment and the intensity of work required to achieve a race fit state. Such supplements are not designed to treat or prevent ulcers, they are not medicines and should not claim to do so, but they play an important part in trying to maintain a healthy digestive system.

Equally using supplements that support hindgut function through promoting the growth of beneficial bacteria, stabilizing the pH of the hindgut or ‘mopping up’ pathogenic bacteria are all part of trying to maintain a healthy hindgut, which has many benefits, and reduces the risk of disorder within this section of the digestive anatomy. 

The most important thing when considering gastric ulcers and other digestive disorders is to be realistic about what you can achieve within your environment, and to be realistic about what difference feeds and supplements alone can make. Any steps that can be taken to reduce risk are worth implementing as the aim is to keep the digestive system as healthy as possible so that the food you provide is converted to the nutrients needed to maximize performance and maintain general good health.

References

1. Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 53-74

2. Ralston,1984; Vulink,2001, cited in Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 58.

3. Vulnik,2001; Boyd 1988; Berger et al.,1999; Edouard et al.,2009 cited in Ellis,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 58.

4. Vulnik,2001 cited in ELLIS,A.D.,2010. Biological basis of behaviour in relation to nutrition and feed intake in horses. In A.D. Ellis, A.C.Longland, M.Coenen & N.Miraglia, ed. The impact of nutrition on the health and welfare of horses. The Netherlands: Wageningen Academic Publishers, 59.

5. Frape, D. (2010) Equine Nutrition and Feeding. 4th Edition. United Kingdom: Wiley-Blackwell

6. Lorenzo-Figueras,M. Merrit,AM. Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses. Am J Vet Res. 2002;63(11):1481-1487

7. Hintz et al 1985 cited in Geor,J. Harris,P. Coenen,M. (2013) Equine Applied and Clinincal Nutrition. China: Elsevier

How HISA has affected the marketing and selling of equine supplements - What trainers need to know

Article by Ken Snyder

In 1834, Thomas Day of Day & Sons in the UK. introduced Day’s Black Drink, an elixir for horses to relieve colic, chills, “low condition” and something called “gripes.” There is no record of the ingredients, and that is probably something best left unknown.

Black Drink was the first known supplement, or product made from natural, not synthetic, substances, as this was the early 19th century. So, too, is heroin derived from a natural substance—poppies. (Created from morphine in 1874, its use on the racetrack was prevalent enough in the early 20th century to help fix races that “horse” became slang for the narcotic in recent history.)

Supplements today range from useless and quackery to many that are considered effective in horse health care by many trainers on the racetrack. In fact, the majority of  Thoroughbred trainers utilize supplements with feed.

Like therapeutic medications and illegal substances, dietary supplements are under the purview of the Horse Integrity and Safety Authority (HISA). Like their drug counterparts, HISA is instituting uniform regulations for supplements in all 50 states. The task falls specifically to the organization’s Horse Integrity and Welfare Unit (HIWU).

Good, bad, or indifferent, the intent of this organization, inarguably, is noble: to make racing safer and healthier for the horses. 

Supplements, however, are seemingly lost in the fog in the scrutiny and attention paid to perhaps the biggest problem in horse racing: medications.

There are potential hazards with supplements, however, and uniform rules across all U.S. racing jurisdictions are in place just as with medications. The key regulation that is now applicable in every HISA jurisdiction specifies that “orally administered vitamins“ and “unsupplemented isotonic electrolyte solutions by oral or intravenous administration” may be administered up to 24 hours prior to post time. This may differ from prior state regulations.

Alexa Ravit, director of communications and outreach for HIWU, outlined the objectives of this regulation and all HISA “regs” in response to an email:

“HISA’s supplements-related regulations (and in particular addressing ‘drug claims’) are intended to protect horsemen from 1) fraudulent or unproven claims of effect; 2) the unknown safety risk to horses in administering these products; and 3) products where the risk of contaminants or unknown components is high due to lack of independent quality controls.”

The task of monitoring and regulating dietary supplements is not nearly as challenging as that for medications, but it is no slam-dunk either. Also, while medications and new withdrawal times for permitted drugs might be a trainer’s focus, trainers should know that, while supplements by and large are safe, there are things to watch for with their use. 

In simplest terms, managing supplements for trainers under HISA/HIWU is following three steps: (1) reading labels (more on this below); (2) being careful in using dietary supplements in combination with approved medications; and (3) not accepting free supplements without understanding what’s on the label.

Mislabeled supplements, according to Rivet, are the major thing that can get a trainer and owner in trouble. She wrote, “If…the product’s labeling…includes a health or structure/function claim, the product is a drug, not a dietary supplement.” Also, drugs are FDA-approved and will carry that information on the label. Supplements won’t. 

In short, trainers need to look first to make sure the supplement does not say “FDA approved.” Supplement labels also should not make “structure/function” claims. HIWU lists these examples:

− Decreases or prevents exercised-induced pulmonary hemorrhaging (EIPH)

− Prevents or treats gastric ulcers
− Manages pain caused by osteoarthritis
− Controls inflammatory airway disease 

− Increases cardiac output
− Increases red blood cell production

The claims are definite, positive and apparently proven by results, warranting approval by the FDA.

Contrast these claims against what will be found for dietary supplements: 

− Sustains lung health
− Maintains gastrointestinal health
− Supports heart health
− Supports bone strength
− Promotes healthy metabolism
− Replenishes electrolytes lost through exercise and sweating

Labels on dietary supplements sound good but stop short of making a promise and, in a couple of instances, are vague at best. “Sustains lung health” and “maintains gastrointestinal health” are things you would want a horse to have after lung or gut issues are solved, and maybe skate closest to a claim like a drug. What supports heart and bone health and strength, respectively, is anybody’s guess. The same goes for promotes healthy metabolism. (Maybe the label will tell one how.) Replenishes electrolytes is a straight-up promise that evidently is achieved with dietary supplements and not drugs. (Gatorade for humans comes to mind.) 

To make another simple distinction, drugs are available only through a prescription from a veterinarian. If a trainer is getting them through another source, there’s potential trouble; but that’s for another story. Supplements are available in tack shops and/or online and do not require a veterinary prescription. 

Ravit, in response to how common it is to see supplements making drug claims contrary to regulations, only said, “It cannot be quantified.” That’s “Governmentese” for “It’s anybody’s guess.”

HISA/HIWU’s own definition of a drug, by the way, is this:

“Under the Federal Food, Drug, and Cosmetic Act, the term “drug” means a product intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, and articles other than food intended to affect the structure or any function of the body.” That’s a mouthful to say it ought to work.; you should get results.

In case you’re wondering why supplements are not regulated by the FDA, the category name “dietary supplements” gives you the answer. The FDA defines them as a “dietary ingredient intended to supplement the diet.” Dietary supplements are not regulated for humans either.

Are they safe? You would think, given the absence of regulation, the answer would be an automatic “yes.” The FDA, however, can take action to remove supplements from the market if they are adulterated (unsafe) or misbranded (misleading). Let the buyer beware.

What a trainer can control are things to avoid, such as mixing supplements with drugs, administering too many supplements, or substituting supplements for drugs altogether. 

HIWU’s language on dietary supplements is actually a bit scary:   

“It is…the responsibility of the manufacturer to ensure the product’s safety and to market the supplement in accordance with applicable law.“

The second part of the statement should give one pause. Yes, the manufacturer is responsible for the product’s safety, but it’s the trainer or trainer’s barn help that is the last person in the literal food chain for the horse. Once a supplement is in a trainer’s hands, he or she is on their own. The safe bet is a veterinarian’s assessment of any risks and/or benefits. 

HIWU addresses this in their literature: “Supplements can interact with some medication with adverse health conditions” advising trainers to “be vigilant and discuss administration [of a supplement] with your veterinarian.”

Ravit also responded with “no comment“ to whether there have already been instances of a supplement producing a positive test for an illegal or controlled substance.

Practicing veterinarians like Dr. Rick Fischer, who has been on the racetrack for 53 years, is, as one would expect, well-versed in the difference between a drug and a supplement. He presents another issue that threatens the health and safety of horses. He and other vets are not always gatekeepers with supplements for trainers. Laymen or salesmen will approach trainers directly promoting supplements. “Worse than that, they’ll give them away: ‘Here are two gallons of this. Use it and see if you like it.’ You really don’t know what the hell you’re getting,” said Fischer.

There are other words on supplements to be mindful of. HIWU’s website warns that “’natural’ does not mean safe, nor does it mean that a product is free of Prohibited Substances.  Neither do “seals of quality assurance” that guarantee a supplement is safe and effective. In short, even practicing veterinarians recommending supplements cannot guarantee safety or effectiveness.

Fischer said there have been instances where a supplement and an approved medication have produced positive tests for banned substances. 

 HIWU’s website advises, “It is crucial to have specialized knowledge from a chemical engineer or pharmacist in order to comprehend and forecast the resulting molecules, due to the intricate interplay between the chemicals involved.” 

 Fischer expounds on the “intricate interplay” thusly: “There’s been positive tests on things that I’ve never even heard of. It’s not something that anybody in their right mind would give a horse. But the chemical breakdown when they’re in combination…who knows? 

“They’ll give you a list of all the different ingredients. Most of it is Greek to these guys and some of it is Greek to me, and I’ve been practicing for more than 50 years.”

Fischer actually parroted HIWU language in saying it would take a chemical engineer or pharmacist to be able to tell “if this molecule matches up with this molecule and what it’s going to come out as.“

Good luck to any trainer looking for a chemical engineer or pharmacist on the backside. 

Dr. Day’s Black Drink, by the way, would not pass muster as a supplement as it claimed to treat colic. As for “gripes,” there is no supplement or drug for that. 

Why are gastric ulcers still a significant concern for horses in training?

With the advances in scoping and increased awareness of gastric ulcers, along with the high prevalence found in horses in training, one may wonder, Why is this condition still such a problem? Do we not know enough to prevent this condition from recurring? 

The short answer is that much is known, and for certain, there are effective medications and many feeds and supplements designed to manage the condition. The underlying problem is that the factors leading to ulceration, at least the most significant ones, are fundamental to the routine and management of a horse in training. Quite simply, the environment and exercise required are conducive to development of ulcers. Horses in training will always be at risk from this condition, and it is important to manage our expectation of how much influence we can have on ulcers developing, and our ability to prevent recurrence. 

Clarifying Gastric Ulceration

Before considering how and why ulcers are a recurrent problem, it is helpful to understand the different types of gastric ulceration as the term most commonly used, Equine Gastric Ulcer Syndrome (EGUS), is an umbrella term which represents two distinct conditions. 

The term EGUS came into use in 1999 and represented ulceration of the two separate locations in the stomach where ulcers are found: the squamous and glandular regions. The two regions are functionally different, and ulceration in either location has different causative factors. This is important when considering what can be managed from a risk point of view at a racing yard. The term EGUS is now split into two categories: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). 

ESGD is the most commonly occurring form and the focus of dietary and management interventions. The majority of horses in training have the primary form of ESGD where the stomach functions normally. There is a secondary form that relates to a physical abnormality which causes delayed emptying of the stomach.

The condition ESGD is influenced by the training environment and time spent in training as noted by researchers looking at prevalence of horses out of training compared to those within training. In this case, 37% of untrained thoroughbred racehorses had ESGD and this progressed to 80-100% of horses within two to three months of training. This effect is not unique to thoroughbreds and is seen in other breeds with an ‘active workload’; for example, standardbreds progress from an average of 44% ESGD in the population to 87% when in training. Such research is helpful in understanding two things: firstly, that ulcers in the squamous section can occur outside of training, and that the influence of exercise and dietary changes have a significant effect regardless of breed. Even horses in the leisure category, which are thought of as low risk or at almost no risk at all, can return surprising results in terms of prevalence.

There are multiple risk factors associated with development of ESGD, some of which are better evidenced than others, and some of which are more influential. These include:

• Pasture turnout

• Having a diet high in fibre/provision of ‘free choice’ fibre

• Choice of alfalfa over other forages

• Provision of straw as the only forage source

• Restricted access to water

• Exceeding 2g of starch per kilogram of body weight 

• Greater than 6 hours between meals (forage/feed)

• Frequency and intensity of exercise 

• Duration of time spent in a stabled environment combined with exercise

Of these factors, the stabled environment—which influences feeding behaviour—and exercise are the most significant factors. The influence of diet in the unexercised horse can be significant, however once removed from pasture, and a training program is entered into, ulceration will occur as these factors are more dominant. An Australian study of horses in training noted the effect of time spent in training, with an increase in risk factor of 1.7 fold for every week spent in training. 

Once in training, there is some debate as to whether provision of pasture, either alone or in company, has a significant effect. Some studies report a lower risk of ESGD when pasture in company is provided for horses in training, whereas others have found no significant effect. The duration of access and quality of pasture involved may be part of the differences in results found. There is a distinct difference between turnout in a paddock that offers a pick of grass and a leg stretch and a paddock rich in well managed pasture. Ultimately a period of turnout whilst in a training program is not enough of a counter-balance to the risks of frequent and intense exercise, coupled with a need for stabled periods and higher rates of compound feeding.

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Gut health - aspects of bad behavior and how to fix it

By Bill Vandergrift, PhD

When performance horses behave or react in ways that are less than desirable, we as trainers and handlers try to figure out what they are telling us.  Is there a physical problem causing discomfort, or is it anxiety based on a previous negative experience? Or, is the bad behavior resulting from a poor training foundation leading the horse to take unfamiliar or uncomfortable situations into their own hands, which usually triggers the fright and flight reflex instead of relying on the handler for direction and stability?  

Often when the most common conditions that cause physical discomfort are ruled out, it may be tempting to assume that the bad behavior is just in the horse’s head or that the horse is just an ill-tempered individual. In my experience, most unexplainable behavior expressed by performance horses is rooted in the horse’s “other brain,” otherwise known as the digestive system. In this article I will explain what causes poor digestive health, the link between digestive health and brain function, and what steps can be taken to prevent and/or reverse poor digestive health.

Digestive health

While most trainers are familiar with gastric ulcers, their symptoms and common protocols utilized to heal and prevent them, there still remains a degree of confusion regarding other forms of digestive dysfunction that can have a significant effect on the horse’s performance and behavior. In many cases recurrent gastric ulcers are simply a symptom of more complex issues related to digestive health.  Trainers, veterinarians and nutritionists need to understand that no part of the horse’s digestive tract is a stand-alone component. From the mouth to the rectum, all parts of the digestive system are in constant communication with each other to coordinate motility, immune function, secretion of digestive juices and the production of hormones and chemical messengers. If this intricate system of communication is interrupted, the overall function of the digestive system becomes uncoupled, leading to dysfunction in one or more areas of the digestive tract.

For example, a primary cause of recurrent gastric ulcers that return quickly after successful treatment with a standard medication protocol is often inflammation of the small and/or large intestine. Until the intestinal inflammation is successfully controlled, the gastric ulcers will remain persistent due to the uncoupling of communication between the stomach and lower part of the digestive tract.

How do we define digestive health? Obviously, digestive health is a complex topic with many moving parts (figuratively and literally). The main parts of a healthy digestive system include, but are not limited to 1) the microbiome, 2) hormone and messenger production and activity, 3) health of epithelial tissues throughout the digestive system, 4) normal immune function of intestinal tissue and 5) proper function of the mucosa (smooth muscle of the digestive tract) to facilitate normal motility throughout the entire length of the digestive tract.

Microbiome is key

A healthy and diverse microbiome is at the center of digestive health. We now recognize that reduced diversity of the microbiome can lead to digestive dysfunction such as colic and colitis, development of metabolic disorders such as insulin resistance, reduced performance and increased susceptibility to disease. Research efforts leading to greater understanding of the microbiome have recently been aided by the development of more sophisticated techniques used to identify and measure the composition of the microbiome in horses, laboratory animals, pets, livestock and people. While these research efforts have illustrated how little we really understand the microbiome, there have been significant discoveries stemming from these efforts already.  For example, a specific bacteria (probiotic) is now being used clinically in people to reverse depression resulting from irritable bowel syndrome (IBS). Bifidobacterium longum NCC3001 reduces depression in IBS patients by directly affecting the activity of the vagus nerve which facilitates communication between the brain and the digestive tract. It should be noted that Bifidobacterium longum NCC3001 has been demonstrated to be more effective at reducing depression in IBS patients than antidepressant drugs commonly used in these same cases. While we do not commonly recognize clinical depression as a physiological condition in horses, the same mechanisms that affect the function of the vagus nerve and brain chemistry in IBS patients can affect a horse’s behavior and reactivity due to intestinal dysfunction, resulting in a horse that bites, kicks, pins its ears or otherwise demonstrates hyper-reactivity for no apparent reason, especially if this behavior is a recent development.

One case in particular I dealt with years ago that had underlying suggestions of depression in a horse, and underscores the importance of a diverse and healthy microbiome for performance horses, was a horse that had been recently started in training and was working with compliance on the track. The problem was this horse seemed to be unable to find the “speed gear.” The trainer had consulted with various veterinarians, physical therapists, chiropractors and others in an attempt to pinpoint the cause for this horse’s apparent inability to move out; and it was everyone’s opinion that this particular horse had the ability but he simply wasn’t displaying the desire. In other words, he was “just dull.”  After reviewing this horse’s case and diet, I had to concur with everyone else that there was no obvious explanation for the lack of vigor this horse displayed on the track even though his body condition, muscle development and hair coat were all excellent. Despite any outward signs of a microbiome problem other than the horse’s “dullness,” I recommended a protocol that included high doses of probiotics daily, and within 10 days we had a different horse. The horse was no longer dull under saddle and when asked to move out and find the next gear, he would readily comply; by making an adjustment to the microbiome, this horse’s career was saved.

There is always a change to the microbiome whenever there is a dysfunction of the digestive system, and there is always digestive dysfunction whenever there is a significant change to the microbiome. Which one occurs first or which one facilitates a change in the other may be dependent upon the nature of the dysfunction, but these two events will almost always occur together.  Therefore, efforts to maintain a viable and diverse microbiome will reduce the chances of digestive dysfunction and increase the speed of recovery when digestive dysfunction occurs.

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Unravelling ulceration - The causes, treatment and prevention for squamous vs. glandular gastric ulceration

By Emma Hardy, PhD

Gastric ulcers remain a common condition facing competition horses. This poses an ongoing and persistent challenge to trainers who face the negative effects of ulcers in terms of training and performance. To address the issue, the typical trainer spends a small fortune on scores of omeprazole and other ulcer remedies, only to find the problem isn’t resolved or simply comes back.

Meanwhile, researchers have been testing the very notion of “what is an ulcer?” The data casts doubt on whether go-to treatment approaches will actually work. A look at what the research now tells us about equine gastric ulcers may provide some new guidance for how best to address this nearly ubiquitous concern.

The two faces of gastric ulceration

While many people think of gastric ulcers as one specific disease, equine vets and researchers refer to gastric ulcers as a “syndrome” (Equine Gastric Ulcer Syndrome, or EGUS). The medical definition of a syndrome describes a set of symptoms and signs that together represent a disease process. In practical terms, this means that ulcers are really a clinical signs—truly a symptom—of underlying disease conditions.

A few years ago, articles began to appear in the scientific press highlighting differences in the healing of ulcers in two distinct regions of the stomach—the upper “squamous” area on the one hand, as compared to the lower “glandular” portion on the other. In recent years, researchers in Australia published a series of articles (Sykes et al, 2014) to “clarify the distinction between diseases in different regions of the stomach” (i.e., to describe the differences between ulcers in the squamous area of the stomach from those in the lower glandular area). The articles described significant differences between the two conditions, including prevalence, risk factors and response to treatment.

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An example of a cherry ulcer

Squamous gastric ulceration

The upper region of the stomach is minimally protected from the corrosive effects of stomach acids. As such, squamous gastric ulceration (i.e., ulcers in the upper region of the stomach) is believed to result from the increased exposure to acid and other contents of the stomach. Ulcers in the squamous region are also more common, affecting upwards of 70% of Thoroughbred racehorses, as demonstrated in multiple studies over the past 20 years.

Glandular gastric ulceration

By contrast, ulcers in the lower glandular region of the stomach are believed to arise from a different set of conditions. The lower portion of the stomach is composed of numerous cell types including those that secrete gastric acid. Because horses secrete stomach acid continuously, the mucosal lining in this lower portion of the stomach is in direct contact with stomach acid at all times.

The lower portion of the stomach is also better protected—the glandular mucosa is lined with a thick layer of mucus that offers natural protection from acid. It is believed that glandular ulceration results from the breakdown of this protective lining. Although no research has conclusively shown exactly how this defence mechanism breaks down in horses, research in humans shows NSAID (non-steroidal anti-inflammatory drugs) use and bacterial agents are contributors.

Based on this, equine squamous gastric ulceration (ESGUS) is a specific condition distinct from equine glandular gastric ulceration (EGGUS).

Beyond the stomach….

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Gut feeling - research into equine gut ulceration

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