April 4, 2013
One of the latest developments in equine colic and gastrointestinal research, according to Anthony Blikslager, DVM, Ph.D., Dipl. ACVS, is his lab's study of isolating stem cells in the intestine, with the idea of ultimately using them to repair injured tissue after colic surgery.
Dr. Blikslager is a professor of surgery and gastroenterology at North Carolina State University College of Veterinary Medicine. He and his lead researcher, veterinary surgeon Liara Gonzalez, DVM, Dipl. ACVS, a Ph.D. candidate, are studying stem cells from normal intestine and intestine that has been resected to understand what happens during intestinal ischemia. Ultimately, the goal is to take stem cells from resected intestine and return them to the anastomosed section of intestine to hasten mucosal recovery.
Although resected intestine is likely to be severely injured, stem cells are relatively protected deep within the mucosal crypts and may therefore be available for use.
“No one has done this before in horses,” Blikslager says, “Perhaps not in any other species. It's entirely new research.”
The intestine is “highly organized,” he says, “so we know where to look for the stem cells.”
Blikslager is hoping that the normal stem cells will help damaged intestine self-renew. He says the next part of his study will address the efficacy of using the stem cells for repairing the intestine.
The initial stages of the stem cell study should be completed by the end of this year, he says.
Dr. Gonzalez will present her findings at the annual symposium of the American College of Veterinary Surgeons this fall.
“We are trying to prevent a horse from developing colic in the first place by encouraging veterinarians to share common sense horse management approaches with their clients,” Blikslager says. “Adequate turnout time for increased grazing, feed with low quantities of soluble carbohydrates, and high forage, even from a hay net in the stall, are all encouraged.”
Feed companies are following better practices, too, he says.
“We used to feed sweet feed with corn and molasses—high carbohydrates,” he says. “Today's feed pellets are higher in fiber and fat, lower in sugar and starch.
“These changes have come about mostly due to high demand of managing high performance horses,” he adds.
Standardized information on horses with colic has been collected for several years now; it helps veterinarians and researchers to evaluate if occurrence rates are changing or improving.
It is difficult to know if the same proportion of horses suffer from colic over time without a broader national study, but more are surviving.
“The survival rate of horses after colic surgery is now in the 80-90 percent range,” Blikslager says. “We've made huge strides in this area. As our numbers rise, we are able to offer more hope to horse owners.
“The occurrence of ileus and adhesions that delay recovery is also reduced,” he says, “and we've learned more about keeping a horse from going into shock.”
Also adding to the increased survival rate is that veterinarians are doing a better job of sending horses with colic to the hospital earlier, so they can be saved by surgery, he says.
“And they are better at getting owners to consider the financial costs earlier, as well as educating owners about equine insurance policies that can help pay for surgery and recovery.”
Blikslager observes veterinarians' presenting more information about treating colic at meetings and conferences.
“More practitioners are sharing information, and then taking that back home to use in their own practices,” he says. “We consistently keep trying to make the survival and recovery rates better.”
As part of the horse's complex and delicate digestive system, any problems in the foregut and the hindgut can cause a chain of physiological events that lead to ulcers.
Hoyt Cheramie, DVM, MS, Dipl. ACVS, says there hasn't been a lot of new work in diagnosing or treating gastrointestinal ulcers, though European veterinarians have presented studies on glandular ulcers, suggesting higher incidences than previously reported. The diagnosis relies on clinical signs and endoscopic examination of the entire stomach, including the pyloric antrum.
Dr. Cheramie is manager of large animal veterinary services for Merial Animal Health.
“There are more challenges in diagnosing glandular ulcers,” he says. “The pyloric antrum and pylorus have to be adequately visualized, which isn't always done or may be difficult in some cases. Many of these glandular ulcers don't result from simple excess acid like most squamous ulcers. Although clinical signs may indicate a gastric ulcer, glandular ulcers may be related to other underlying conditions; the ulcers are secondary.”
Gastroscopy is still the best method to diagnose equine gastric ulcers, Cheramie says.
“It's the only way to conduct a full evaluation of the entire stomach and the first 15-20 cm of the duodenum. The scopes let practitioners diagnose the ulcers accurately and with quick-acting response therapy, they can easily monitor healing.”
Colonic ulcers, on the other hand, are more difficult to diagnose.
“We may suspect GI ulcers by a loss of performance, weight and condition, training issues, NSAID use, or other signs in the horse's history,” he says. “After we rule out other causes, colonic ultrasound can help determine the diagnosis.”
Cheramie says there is not a distinct therapy for colonic ulcers, though medications and appropriate feed management can provide a better environment for the colonic mucosa to heal.
Treatment, though, is not always as simple as just dispensing drugs and telling horse owners to upgrade feed.
At the American Association of Equine Practitioners conference in 2011, Scott Stanley, Ph.D., of the University of California, Davis, presented findings addressing inconsistency in compounding omeprazole for treating gastric ulcers.
Stanley compared powders, suspension and paste products and found many did not contain the labeled concentration and that the potency of the ingredients degraded over time, leaving unstable compounds on the shelves and on veterinary trucks that didn't have rapid turnover of medication.
From gastric ulcers to hindgut acidosis, equine practitioners agree that prevention is preferable to emergency treatment.
Horse owners should be encouraged to use only quality feed, Blikslager and Cheramie agree.
As undigested processed feed reaches the hindgut, the cecum and the colon convert the sugar and starches to an excess of lactid acid, which can lead to the formation of colonic ulcers and other digestive problems.
“In the last 10 to 15 years, feed manufacturers have been looking more closely at the feedstuffs used in their products,” Cheramie says. “Research studies have helped these companies develop better products based on how the horse's digestive system works and uses the nutrients in feed.
“National equine feed manufacturers have become quite responsive in addressing metabolic and GI issues by developing more appropriate formulas,” he says. “And now we're even on the second generation of feed improvements, which shows concern for the horse's health. Of course, additional research is always needed.”
Franklin L. Pellegrini, DVM, believes most colic is avoidable. He is vice president of veterinary science for Freedom Health LLC, Aurora, Ohio.
Dr. Pellegrini's studies indicate that “Colonic ulceration may be present in up to 63 percent of performance horses, and 54 percent of performance horses may have both gastric and colonic ulcers.”
Freedom Health has developed its nutraceutical, Succeed, designed to “normalize a horse's foregut and hindgut bacterial flora, in part by slowing down the passage of grains through the GI tract and maximizing nutrient uptake,” he says.
A veterinary formula of the supplement is available.
When horse owners observe early signs of colic, they should be educated to consult their veterinarians promptly.
“Veterinarians should consider testing fecal pH and perhaps using a fecal occult blood test to help differentiate foregut and hindgut lesions,” Pellegrini says. “The presence of albumin above a certain level is proof of a colonic ulcer.”
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