Odds On Racing - Harness Racing

The Equine Gastric Ulcer
By Kimberly A. Rinker

Equine gastric ulcers are a common occurrence in racehorses, and the first incidences were recorded some 4,000 years ago, during the first and seventh centuries. The Romans were known for treating horses with powders made from corals in order to treat equine ulcers. In the last two decades of the 20th century, the incidence of equine gastric ulcers in racehorses has been determined to cause a significant deterrent to peak performance.

Frank Pipers, DVM, MS, Ph.D. is considered an expert on the subject of equine gastric ulcers, and was instrumental in the development of the product known as Gastrogard. A graduate of The Ohio State University, Pipers is considered to be an expert in the field of equine gastroenterology, and is the author of over 75 publications. He has served on the staffs of the University of Florida and Tufts University, and was responsible for the introduction of echocardiography within veterinary diagnostic procedures. His earlier research focused on thoracic diseases and diagnostic ultrasound.

According to Pipers, in the majority of horses with ulcers, lesions will occur in the squamous mucosal portion of the equine stomach. These ulcers are craters which form in the lining of the stomach, caused by the corrosive effects of hydrocholoric acid (peptic activity) eroding away the layers of the aforementioned stomach lining. The equine stomach has two parts, the squamous mucosal and the glandular portion, with only 10% of the ulcers occurring in the glandular portion.

The decisions regarding treatment of equine gastric ulcers over the years has been varied concerning what medication is best to use, and for how long. Pipers says that proper diagnosis is best made utilizing an endoscopic exam, in which a three-meter long scope is inserted into a horse's stomach.

"Prior to an endoscopic exam, the horse should be given an eight to 12-hour fast," Pipers said. "Usually, mild sedation is all that is required in order to examine the horse endoscopically. Once inside the stomach, the veterinarian is then able to determine and define the stomach ulcers, and their severity. Then the veterinarian will be able to develop a strategy for a treatment plan."

What causes these ulcers in the first place? Too much acid in the stomach for too long," says Pipers. "We've found that ulcers are more prevalent in Standardbred geldings than in stallions, and those horses over the age of three appear more to have ulcers than younger horses. However, foals and young horses are not immune."

"Horses secret gastric acid continuously through the day, unlike people," Pipers explained. "Gastric acidity is low when horses consume food or roughage, such as hay or grass. Gastric acidity thus is extremely high when horses do not eat. In foals who are sick and who haven't eaten for an hour or two, their stomachs are on fire."

According to Pipers, gastric ulcers form quickly-in 48 to 72 hours-and very significantly. Horses on pasture tend to have normal, healthy stomachs without ulcers, while horses confined to their stalls on a near 24-hour basis tend to be prime candidates for gastric ulcers.

A variety of factors can contribute to gastric ulcers. For instance, prolonged stall confinement, a change in hay or feed, shipping, a change in environment (stress), training and competition stress. Race horses and other non-racing equine athletes, such as Olympic-level three day event horses, have gastric ulcers, with 50% to 90% of those ulcers in the severe ranges. Nearly 60% of non-racing performance horses have shown to have ulcers, Pipers said.

"There is evidence of a severity and increase in ulcers as the severity of the training increases," Pipers said. "Treadmill training seems to induce ulcers; although cause and effect association has not yet been determined."

Horses with gastric ulcers will invariably become poor eaters over time, and as a result, will often be classified as "bad keepers." A diminished appetite, a lackluster coat, a lethargic attitude, chronic diarrhea, recurrent colic, and weight loss are all clinical signs of intense gastric ulcers in horses.

Pipers said that the primary objective in the treatment of these ulcers is to reduce and neutralize the acidity in the equine stomach, thus allowing the lesions within the stomach to heal.

"Gastric acid secretion can be inhibited by certain drugs," Pipers explained. "Omeprazole can inhibit acid secretion by 90 to 99% for up to 24 hours, and this in turn stimulates rapid ulcer healing with a long duration of action and very few side effects."

Omeprazole is the active ingredient in the world's leading human anti-ulcer medication (Prilosec in the United States, Losec elsewhere).

Up until the late 1990s, equine gastric ulcers were generally always treated with cimetidine and ranitidine, although neither were approved for use in horses. Both are approved for used in humans as Tagamet (cimetidine) and Zantac (ranitidine), and both are known commonly as histamine (H2) antagonists. These antagonists are used by chemists within these specific medications to help inhibit gastric acid secretion in the equine stomach. It was typically recommended to administer cimetidine and ranitidine orally or intravenously; cimetidine four to six times daily and ranitidine two to three times daily, for a period of ten to 20 days in order to ensure complete healing. This "H2 antagonist" therapy was often recommended for a long as four weeks in order to ensure complete healing of all stomach ulcers.

"In order to come up with a product which shut down acid production in the equine stomach, several stages of planning took place," Pipers said. "First, we needed a development program of the product, and then we needed to figure out dosage, and the optimal formulation to deliver the dose. We also needed to conduct field trials for acceptability in the real world environment."

Pipers and his colleagues set about testing 100 thoroughbred racehorses, under racing conditions in six separate field trials in Tennessee, Oklahoma, Missouri, Illinois, Indiana and California.

"We found that in the test group that the horses treated with omeprazole responded very well in regards to the lessening of gastric ulcers," Pipers explained. "Within four weeks times 99% of those horses had improved and 87% had healed."

Of those horses who were treated with a continuing dose of the omeprazole, 84% showed no signs of relapse after another 30 days, while 92% of horses who were taken off the treatment showed ulcer relapses after the same 30 days.

"The next step was to formulate the product, once we had established the fact that it did indeed work," Pipers concluded. "Having a paste in a once-a-day dose, is a very user friendly product, and after vigorous testing, we were able to come up with a dosage which would be applicable to all horses, including foals."