Gastroduodenoscopy: What to Expect

Your horse might have health problems that you can't see. These health problems could cause a change in behavior, a decrease in performance, or a change, even a minimal one, in overall health. But veterinarians have a variety of ways to look inside your horse to see what might be bothering him. One of these methods is gastroduodenoscopy, which allows the veterinarian to see the interior of the esophagus, stomach, and duodenum with the use of a gastroscope. During the American Association of Equine Practitioners (AAEP) convention, Michael Murray, DVM, MS, technical director for Strategic Development at Merial Equine Global Enterprise, presented "How to Perform Gastroduodenoscopy" to attending veterinarians. But what can a horse owner expect from this procedure, and what will the horse experience?

Preparation for this endoscopic procedure begins with withholding feed from the horse. This allows for emptying of the contents of the stomach so that the veterinarian can get a better view during the procedure. Foals that are still nursing without solid feed can nurse until two to four hours before the procedure, according to Murray. Foals eating solid feed should have feed taken away from eight to 12 hours beforehand, but they are able to nurse until two to four hours beforehand. If feed and milk is withheld for longer, hydration might become a concern. If it's anticipated that the foal will struggle or become overly stressed, then the veterinarian might decide that sedation is necessary. This will help the procedure go more smoothly for all involved. The procedure can be performed with the foal standing or laying down.

Adult horses will usually have the procedure done while standing, in which case sedation is necessary. This will help make the horse feel more comfortable. Feed is withheld for eight to 12 hours, and water is withheld for two to four hours beforehand. Since a horse will eat anything if he is hungry enough, all hay and bedding should be removed, and the horse should be muzzled, said Murray. Be careful to remove manure also, since horses have even been known to eat their own manure.

Murray said the use of a twitch is useful for many horses. It's usually not a good idea for the owner to be the handler of the horse, since it's easy to get wrapped up in what is being displayed on the monitor and forget about the horse. However, if it happens that you must be the handler, keep an eye on the horse first since he could have an unpredictable reaction to the procedure. Murray feels that it is important for the owner to be present during the procedure so that they can see what he is seeing.

The endoscope is first passed through the nostrils, and this is the most objectionable part of the exam for the horse. As the endoscope reaches the esophagus, the veterinarian will look around for any abnormalities. Squirting water into the endoscope biopsy channel can help the horse swallow. The stomach is then expanded as air is blown into the endoscope. This allows the veterinarian to view the nonglandular and glandular regions of the stomach. The horse should tolerate this well, although rarely a horse might experience some abdominal discomfort. The remaining contents of the stomach are rinsed from the surface with tap water. If there is too much fluid, some of it might be removed using the endoscope biopsy channel or a nasogastric tube.

The veterinarian will not be able to see the bottom of the stomach since the endoscope advances into dark colored gastric fluid and remains of ingested food. The endoscope can then be advanced into the pylorus (the opening into the intestine) into the duodenum (the beginning of the small intestine). Murray discussed the importance of examining the pylorus and duodenum. He had previously found 59% of 162 horses to have erosions or ulcers in this area, which were sometimes severe. Many of these horses had normal gastric squamous mucosa, which is the area of the stomach where gastric ulcers usually occur. He said that he has examined the proximal duodenum of over 100 horses, and most horses are normal. However, he has noticed pronounced mucosal reddening, erosions, and raised, irregular lesions in some.

After the procedure is finished, air should be removed from the horse's stomach. It is rare for a horse to experience abdominal discomfort afterwards. Once a veterinarian has been able to view the horse's esophagus, stomach, and duodenum, treatment of any abnormalities can begin.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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