dr. ben sykes | Horse Racing Free Tips

Thoroughbreds and gastric ulcers go together like a picnic and ants. Medications like omeprazole can effectively help treat or prevent gastric ulceration and has important welfare benefits, making these drugs extremely popular in the racing industry. However, the benefits of omeprazole may be overshadowed by some potential drawbacks that may dampen its use in some cases.

Between 80 and 100% of Thoroughbreds have ulcers in the squamous or upper region of the stomach (equine gastric squamous disease, EGSD). An additional 10-60% or more of Thoroughbreds also suffering from gastric ulcers in the glandular (lower) region of the stomach (equine gastric glandular disease, EGGD).

Ulcers, which are erosions of the lining of the stomach, cause discomfort to the horse. Signs of gastric ulceration manifests in various ways such as a dull hair coat, weight loss, bruxism (grinding teeth), and poor performance.

“Squamous ulcer disease results from management practices and isn't limited to just Thoroughbreds. Feeding any horse involved in high intensity or long duration of work high grain, high carbohydrate but low roughage diets will increase the risk of disease,” said Dr. Ben Sykes from the Equine Clinic, Massey University, New Zealand.

Medications like phenylbutazone (commonly known as “bute”) or other non-steroidal anti-inflammatory drugs (NSAIDs) commonly used in horses may also contribute to the development or worsening of gastric ulcer disease although they are generally considered safe for short durations at label doses.

Given the importance of managing EGUS to optimize the health, welfare, and performance of Thoroughbreds, various medications have been developed. Sucralfate coats the ulcers to prevent further damage and allow healing, ranitidine and omeprazole decrease the acidity of the gastric juice, and misoprostol protects the lining of the glandular mucosa in the lower part of the stomach.

Manufacturers of most commercial preparations of omeprazole recommend treating ulcers with 4 mg/kg per day for four weeks. To prevent recurrence of gastric ulceration, horses can be treated longer term at a lower dose, usually 1 to 2 mg/kg per day.

Like any medication however, omeprazole doesn't always come up roses. In addition to the fact that long-term administration of any medication can be economically draining, omeprazole hasn't been tested for its long-term safety. Further, even its short-term use may not be as innocuous as one might think.

In a recent article in the journal, Equine Veterinary Education, Sykes shared four major concerns associated with omeprazole administration:

Rebound gastric hyperacidity. After abruptly discontinuing omeprazole, the gastric contents may become more acidic than normal, which may explain the rapid recurrence of ulcers in some horses.
Changes in fecal microbiome. The population of microorganisms in the equine hindgut that contribute to the overall health of the horse can be negatively affected by any medication. Omeprazole does not appear to alter the microbiome after 28 days of omeprazole administration, but the long-term effects have yet to be studied.
Interaction with NSAIDs. Bute and other NSAIDs can contribute to the development of gastric ulcers, and many horses treated with these medications receive omeprazole.
“A recent study showed, however, that while omeprazole helps prevent gastric ulcers potentially caused by NSAIDs, this drug combination appears to cause hind gut issues such as small colon impactions and diarrhea that can potentially be fatal, especially when high doses of phenylbutazone are used,” said Sykes. “Considering this, my current recommendation is to avoid the co-administration of NSAIDs and omeprazole, or at least to use the lowest effective dose possible for both drugs. If concerns about the potential for NSAIDs such as bute to cause gastric ulcers persist in a particular patient, then sucralfate is a reasonable alternative to consider.”
Increased fracture risk. Increased fracture risk is a significant concern with omeprazole administration in humans, both in geriatric and juvenile populations.
“To date, no evidence exists that omeprazole has a similar effect in horses,” said Sykes. “Studies looking at the short-term effects of omeprazole on bone metabolism have found no effect of the drug. But there is data in horses that the proposed pathways that contribute to fracture risk in humans also occur with short-term omeprazole administration in the horse.”

Long-term data are both lacking and much needed, considering the relevance of fracture risk in the racehorse industry.

In short, omeprazole is used widely both for short- and long-term use for EGUS in horses, has good reported efficacy, but may be associated with a number of important safety concerns.

“In other words, omeprazole has a high safety profile, but it does not mean omeprazole is universally safe,” Sykes said.

Ideally, veterinarians, trainers, and owners would seek to use the lowest possible dose of omeprazole that maximizes outcomes.

“Optimizing absorption will help us get more bang for our buck,” Syke said. “Giving omeprazole after fasting overnight will allow more of the drug to be absorbed compared to horses that had been fed. This means that we only need to administer about half the amount of the drug to achieve the same level of acid suppression if given when the horse has not fasted.”

As we know, though, one of the cornerstones of improving management of horses with EGUS is ensuring horses have continual access to hay. So, should we worry about withholding hay overnight? Sykes advised absolutely not.

“Horses naturally do not eat overnight even if they have ad libitum hay. Instead, they spend most of that time resting or sleeping,” he said.

Sykes therefore proposed the following tips for using omeprazole as safely and effectively as possible based on the currently available information on this drug:

Fast horses overnight. Take away the horse's feed by 10 p.m.
Administer omeprazole first thing in the morning before feeding and exercise. Peak absorption of omeprazole from the gastrointestinal tract into the circulation occurs around 60 minutes so the horse should remain unfed for 30 to 60 minutes after administration
Start treating horses with only 2 mg/kg omeprazole per day. Only increase the dose to 4 mg/kg if needed (based on a lack of clinical response or gastroscopy—direct visualization of the stomach wall using a scope by a veterinarian)
Administer other medications for gastric ulcers separate from omeprazole.

“Sucralfate, ranitidine, and misoprostol should not be administered at the same time as omeprazole. These medications will interfere in the action of omeprazole and the pH of the stomach contents will not increase as expected,” Sykes explained.

Instead, these other medications can be administered at the time of feeding, 30 to 60 minutes after omeprazole administration, or in the afternoon (omeprazole is given once a day in the morning).

“Exercising after omeprazole administration and feeding, even if just a small meal, will also increase the effectiveness of omeprazole because most of the damage to the squamous mucosa in the upper region of the stomach occurs during exercise,” Sykes said.

Overall, Sykes suggested that owners should not necessarily be deterred from using omeprazole, but should certainly cognizant of these safety issues.

“Omeprazole, like any prescription medication, should be used in a safe and responsible manner,” he said. “Implementing the recommended management changes alongside administration will help achieve either comparable or even more complete treatment responses and better outcomes with lower omeprazole doses. This not only has financial benefits but is also expected to further improve the drug's safety profile by using the minimally effective dose.”

Dr. Stacey Oke is a seasoned freelance writer, veterinarian, and life-long horse lover. When not researching ways for horses to live longer, healthier lives as athletes and human companions, she practices small animal medicine in New York. A busy mom of three, Stacey also finds time for running, hiking, tap dancing, and dog agility training.

The post Here’s What To Keep In Mind When Giving Your Horse Omeprazole For Gastric Ulcers appeared first on Horse Racing News | Paulick Report.

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Gastric ulcers in horses have been a problem for trainers, owners, and managers for years now, and studies suggest a majority of racehorses and performance horses suffer from them. As a result, they've been a topic of much academic research in the past five years.

Dr. Ben Sykes, assistant professor of equine internal medicine at Massey University, sat down with the Grayson Jockey Club Research Foundation recently to give the public an idea of what we've learned in the past five years and what he and other researchers plan to focus on in the next five.

A complete replay of Sykes's seminar is below. A few key takeaways:

First of all, the term most of us use to describe this issue in horses is a bit outdated. Equine Gastric Ulcer Syndrome (EGUS) is still the common terminology in lots of advertising and lay articles about the topic, but that's actually a holdover from before we knew that there were two distinct types of ulcer-like disorders that could be happening in a horse's stomach.
Technically, there are now two terms in use which are more specific: Equine Squamous Gastric Disease and Equine Glandular Gastric Disease. Squamous gastric disease refers to ulcers in the upper half of the stomach, characterized by ulcers easily viewed on gastroscope. Glandular Gastric Disease refers to lesions [which technically aren't ulcers, but look and behave similarly to true ulcers] in the lower half of the stomach, particularly around the part where the stomach empties into the gut.

Until recently, gastroscopes were only long enough to reach the squamous part of the stomach, so we didn't really know if there could be problems lurking further along. The two terms really only came about in the last several years when the longer gastroscopes became common. Research we have on gastric ulcers in horses prior to 2015 is almost certainly referring to Equine Squamous Gastric Disease. Equine Glandular Gastric Disease is much less understood.
Why does this matter? The two diseases exist independently of each other, with different possible causes and different treatments. For Sykes, squamous ulcers come about as a result of management decisions that increase damage of stomach acid to the top of the stomach. The ulcers are caused by two types of acid – hydrochloric acid, which is reduced by common treatments like omeprazole, and volatile fatty acids, which are not addressed by omeprazole and come about as a way to digest grain. Sykes said researchers think that this acid damage occurs during exercise.
Studies have shown that exercise drops stomach pH, increasing the acidity. This is primarily because the abdominal muscles at a trot or canter squeeze the stomach into an hourglass shape, pushing the acid that was at the bottom of the stomach, where it was being buffered by a lot of fibrous feed material, toward the top, which is more likely to be fairly empty or contain thinner, more watery material. It's quite easy for the acid to splash around at the top of the stomach and cause damage.

High carbohydrate diets can be a problem for horses with this disorder since they require more volatile fatty acids to break down the structure of the carbs. That doesn't mean you can't feed an ulcery horse grain, Sykes said – you just have to do it in moderation. A balanced commercially processed feed provides a lot of important nutrients to working horses. Low carb, high fat and high fiber diets are good choices for keeping a horse fed without increasing ulcer risk.
Equine Glandular Gastric Disease on the other hand, occurs in the lower part of the stomach where the environment is commonly pretty acidic. Sykes said he thinks the disease occurs because the natural defense mechanisms of the stomach lining there have been compromised for some reason.
There's no evidence diet impacts Equine Glandular Gastric Disease, but workload might. Studies have shown that long stretches of work without days off make a horse more likely to exhibit signs of Equine Glandular Gastric Disease, and behavioral stress may be a factor as well. Horses with glandular ulcers have been shown to produce higher levels of cortisol in stressful situations than horses without glandular ulcers, though we don't know whether stress caused the ulcers or the ulcers worsened the horses' stress reaction.
A few discoveries from recent data: Perhaps surprisingly, omeprazole, the go-to treatment for gastric ulcers, does its best work on a relatively empty stomach. One study compared the acidity of horse's stomachs when they were fed free choice hay round the clock versus the usual racehorse schedule of two big meals with some hay offered in between. Researchers found that the drug worked best when the horse had an empty stomach first thing in the morning.
It seems misoprostal may be a better treatment for glandular ulcers than omeprazole, which works well on squamous ulcers. Both options improved horses' symptoms, but the misoprostal showed more healing of lesions on gastroscopy.
A new form of omeprazole available via intramuscular injection may show promise for horses with both types of ulcers. The drug isn't accessible in most of the United States yet, but one peer-reviewed study showed 100% healing of squamous ulcers and 75% healing of glandular ulcers after two doses.
For a long time, veterinarians have suspected a connection between prolonged use of non-steroidal anti-inflammatories like phenylbutazone and ulcers, so for a while they suggested giving omeprazole along with bute as a preventative. Sykes pointed to one peer-reviewed study from 2020 that showed that may not be a good idea. In the study, horses were examined after being given a course of drugs — either bute alone or bute given alongside omeprazole. The bute group did show signs of ulceration while the other group didn't, but there was a high rate of serious intestinal issues among the group receiving bute with omeprazole. In two cases, those intestinal problems proved fatal.
One of the big questions Sykes hopes to answer in the coming years is the potential side effects of long-term omeprazole use in horses – particularly whether or not it increases fracture risk by changing calcium and magnesium absorption. Initially, long-term use of certain types of ulcer drugs in humans was thought to increase fracture risk only in geriatric patients but a recent study in pediatric patients showed that short term treatment of very young children resulted in a 13 percent increase of fracture by age 12 or 13.
We don't have any data to show whether or not the same thing occurs in horses, and part of the reason is that it's difficult to exclude other risk factors for a fracture. The human data does have Sykes worried – not only about the intersection of ulcer treatments and fatal fracture risk, but also about whether ulcer treatments could predispose a horse to bucked shins or other bone maladaptive disorders.

Sykes said thanks to Grayson Jockey Club Research Foundation, he and others are currently constructing studies to look at the impacts of common ulcer drugs on mineral absorption in horses. With any luck, we should know more about the issue in the coming years.

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