GASTROENTEROLOGY

Managing Gastric Illness

Nonpharmacological Management of That Unique—and Frustrating—GI Tract

By Marie Rosenthal,MS

The management of equine gastric diseases is one of those cases where prevention is better than cure, according to Galye Hallowell, MA, VetMB, PhD, CertVa, DACVIM, DACVECC, DECVSMR, PFHEA, FRCVS, a professor at the University of Nottingham, in England.

Preventive measures include diet and perhaps environmental changes that could address the horse’s stress. However, not all nonpharmacologic management remedies are created equal.

“When we are thinking about management, we really think about prevention as well as our acute pharmacologic management,” Dr. Hallowell said at the recent ACVIM Forum 2023. “And where preventative measures are concerned, think about the diet, but also about other management changes.”

She gave what she acknowledges was a rare example. She had a patient, a 9-year-old Andalusian stallion, who used to be a breed horse. He was turned out in a paddock near a variety of mares, but there was an electric fence around it. He could not touch the other horses. After trying multiple things for his severe glandular disease, she recommended they move him away from the mares.

“When he got turned out, he had paddocks all around him where he was surrounded by mares in the summer. So, we had a chat about the fact that this was probably a relatively stressful environment for him,” she said, because he couldn’t breed with these mares.

“We moved him to a yard where he was with 2 other geldings. There were no mares,” she said. When she rescoped him 8 weeks later, his behavioral changes had gone, and his glandular disease had gone, and he received no therapy. And in fact, the only thing I did was move him away from mares,” she said.

In addition, nonpharmacologic management may be cheaper than prescription medication. “If we can get these nonpharmacologic therapies to work, we should hopefully improve affordability of treatment, and, perhaps in some cases reduce our reliance on antimicrobial use, which is going to become more important as time moves on.”

The risk factors and management of equine squamous gastric disease (ESGD) are well understood and include dietary changes, turnout on pasture, providing small amounts of forage before exercise and minimizing stress. Corn, safflower and other oils containing omega 6 fatty acids, which may be useful for ESGD. Fish oils, which contain omega 3 fatty acids, might also be useful. The data show horses that received those safflower oil and/or fish oil supplements, which are higher in omega fatty acids, had a much lower prevalence or no ESGD, and when it did have squamous disease, the grade was much lower, she said.

“Corn oil might be beneficial,” Dr. Hallowell said. “Certainly experimentally, it decreases gastric acid output and increased prostaglandin E2. The omega 6 safflower and fish oils may be more beneficial, and I think we need to watch this space,” as more people are researching it.

Some studies have looked at sea buckthorn berries, which are rich in large numbers of nutrients, and people have found that they might reduce ulcer scores. However, the jury is still out on glandular disease. Continual use may worsen disease, rather than improve it.

Another more recent study looked at a seaweed derived calcium supplement. Although it did have an impact on gastric pH, the effect was short acting. “It's probably not causing acid suppression for anywhere near the amount of time we would need to see any form of clinical improvement,” Dr. Hallowell said.

Genetics, the environment, exposure to bacteria, viruses, parasites and diet can all play a role in gastric illnesses.

Aloe vera is another product with very beneficial properties. One study compared it to omeprazole for glandular disease, but she said that might not have been a fair comparison. The aloe vera provided some healing and improvement rates but they were lower than omeprazole, according to Dr. Hallowell. “But obviously they were never going to be equivalent, which is no surprise to any of us, I'm sure.”

Pectin-lethicin could be used as a mucosal protectant, but there is no evidence that it's going to be beneficial for healing. But it might be good in the armamentarium for protecting against disease.

IBD Appears to Be Increasing

Anecdotally, the prevalence of irritable bowl disease (IBD) is increasing among horses, but it’s hard to know whether it is an increase in disease or just better recognition, she admitted. Horses with IBD can present as recurrent colic, can present with anorexia and unexplained weight loss, and sometimes with diarrhea. “I would say I see weight loss most as a presenting sign,” she said.

Intestinal wall thickness on ultrasonography, documentation of malabsorption, as well as rectal and or duodenal mucosal biopsies are used typically to diagnose IBD.

Genetics, the environment, exposure to bacteria, viruses and parasites, and diet can all play a role.

Steroid or azathioprine are frequently used to control inflammation, but if other management is not provided, “we're setting them up to fail or to get recurrence,” Dr. Hallowell said.

In people, early use of antimicrobials has been shown to alter the intestinal microbiome, which can increase the risk for Crohn’s disease or IBD, she said. Breast feeding is found to be protective.

“And we know that fiber and olive oil are usually protective, and that stress is a risk factor,” she said.

“The other thing that we know is that dysbiosis plays a pretty big role in IBD in both people and dogs, so we assume it does in horses,” she said.

It's perhaps not quite as clear yet, but it is a large area of research. “We're trying to get a real understanding of the normal microbiota, it's variation and also the things that change it,” she said.

They can have an impact on the microbiota in the short term, but whether they are able to make those medium- and long-term changes is also still a question.

Much of IBD management in dogs and cats focuses on exclusion diets, chicken-free and hydrolyzed diets. Many dogs and cats will respond to nutrition alone, she said.

GI DISEASE MANAGEMENT TIPS

Preventive measures

• Evaluation and manipulation of diet

• Other management changes

Nonpharmacologic therapies

• Improve affordability, if successful

• Reduce reliance on antimicrobials

Many promising products and concepts

• Use care in interpreting their use and success

• Extrapolation from other species might not be applicable

Short-Fiber Diets

In her research, she found that short-fiber diets in horses should be easier to digest, and they may well form a different source of fiber to what the horse was exposed to before, which could be very important for IBD.

“The other thing with the use of short fiber diets is trying to simplify that diet and reduce the number of cereal proteins that horse is exposed to, particularly if those risk factors are similar to those in other species. We also know that the short fiber diets are going to be a lower volume, so it should be easier for them to move through the GI tract, particularly in animals that have gut motility disorders,” Dr. Hallowell said.

Although these short fiber diets may well have a place in horses with severe dental disease or mastication challenges, there might be a secondary impact on how that diet is processed in the GI tract.

She presented a study in 2020, where they looked over clinical case records of horses older than 6 years of age. They were looking for those with recurrent colic, which was defined as greater than 3 episodes in the previous 3 months with or without previous colic surgery and/or weight loss or diarrhea. They tried to determine weight over time and the overall outcome.

“These horses were feed a standard short-fiber diet that was split into 3 or 4 feeds per day,” she said.

The horse's weight was evaluated, and the diet was adjusted if they were gaining or losing weight. Some horses had access to pasture, and some did not depending on the time of year. They identified 32 horses between 8 and 22 years. They were predominantly Draft or Warmbloods; 53% were geldings and 45% were mares. Almost 40% had undergone colic surgery, 7% for large intestinal displacement and partial torsions, and 25% for epiploic foramen entrapment.

The presenting signs were recurrent colic (69%), chronic or recurrent diarrhea (25%) and weight loss (6%).

They had motility studies for 88% of the horses, all those with recurrent colic, those with weight loss, and a few with diarrhea.

All the horses were fed a standard short fiber diet of alfalfa, unmolassed sugar beet, grass or other cubes and up to 50 mL vegetable oil for 6 weeks to 3 years.

The weight was maintained or increased slightly in 81% of horses, weight loss was seen in 19%.

Thirteen percent of the horses showed signs of colic while on the diet, and these horses died or were euthanized. Two horses were removed due to signs of abdominal pain and diarrhea, which abated when the diet was reintroduced.

“From this group, our 1- to 2-year survival was 80%,” she said.

“We didn't stop the diet in all cases to look at the impact of the diet or whether it was just mother time that improved matters. But what we did note was that it certainly seemed to resolve signs in 80% of cases,” Dr. Hallowell said.

Research is still be done on pre and probiotic, but so far, the efficacy data are really lacking, particularly for off-the-shelf items. Fecal transplantation has been used in practice for several decades, but that is also lacking evidence, she said.

“When we are thinking about nonpharmacologic management of GI disease, think about manipulation of the microbiome when we know more, maybe consider the short fiber diets and really think about the oils that we use,” she said. Gluten-free diets might be helpful as they are in some people.

Also, consider how antibiotics and antiparasitics in early life might affect the adult horse’s microbiome.

“I think there's lots of promising products and concepts, but we just need to interpret them appropriately,” Dr. Hallowell said. “And remember that extrapolation from other species might not result in success. It might, but we always must note the horse has got that unique if not frustrating gastrointestinal tract.”