About Equine Gastric Ulcer Syndrome (EGUS)
There are two main types of gastric ulceration in horses: squamous and glandular. The encompassing term is equine gastric ulcer syndrome (EGUS). The two types are referred to as either ESGD for equine squamous gastric disease or EGGD for equine glandular gastric disease. The underlying mechanisms of this syndrome can be simplified to excessive acid exposure in the gastrointestinal tract.
If you own a horse, chances are you know someone who has had to deal with EGUS. The prevalence of this syndrome is concerning. It has increased drastically with domestication; the prevalence estimates for EGUS in adult horses range from 60-90%. This varies based on management and performance level. The prevalence in active racehorses, for example, is estimated to be over 90%. This high prevalence in performance horses is often attributed to the changes in management.
The available research clearly illustrates key risk factors for equine gastric ulcers. The top reported risk factors are fasting, high starch diets, low roughage diets, transport, and stall confinement. It is well known that horses are not meant to fast—they are grazers! This means having continuous access to forage. On top of these nutritional management risk factors, stress, and administration of non-steroidal anti-inflammatories (NSAIDs) such as phenylbutazone (commonly referred to as bute) have also been closely associated with an increased risk of gastric ulcers.
Since horses have evolved to be trickle feeders, they have continuous acid secretion in their digestive tract. Therefore, when intermittent fasting occurs there is a disruption of the normal pH of the stomach contents, allowing increased concentrations of acid to contact the stomach lining. Low roughage diets have a similar effect. When a horse’s diet is not adequately providing roughage there is less saliva due to reduced chewing and a “forage mat” does not develop in the stomach. This reduces the horse’s ability to buffer the strong acid and results in increased gastric fluidity.
For diagnosis, a gastroscopy must be done by your veterinarian to confirm the presence of ulcers. When gastric ulcers are diagnosed via gastroscopy the veterinarian will assign a score based on severity. The scores are 1-4 with 4 being the most severe.
|0||The epithelium is intact and there is no hyperkeratosis|
|1||The mucosa is intact, but there are areas of hyperkeratosis (discolouring/thickening of mucosa) or hyperemia (reddening)|
|2||Small, single or multifocal lesions|
|3||Large single or extensive superficial lesions|
|4||Extensive lesions with areas of apparent deep ulceration|
Let’s quickly review the anatomy of the equine stomach. Below is an illustration clearly showing the various stomach regions that will be mentioned in this case study. As you can see in the illustration, the stomach has two distinct regions; non-glandular (or squamous) and glandular. Acid is produced in the glandular regions, which is more resistant to ulceration. Ulcers are more prevalent in the non-glandular region but can occur in both regions. Use this image to refer to when the ulcer location is discussed in this case study.
Jasper is a mature Rocky Mountain Horse and has lived at Wishing Well Farms since 2010. Since this time, he has lived outdoors in a mixed herd on a nine-acre hilly pasture with a large bank barn for shelter. Up until 2021, Jasper was on a forage only diet (no grain or supplements). In 2021, the forage at the farm tested low on some key nutrients. Due to this, he was supplemented at label with Buckeye Gro N Win until spring 2022.
When outdoors Jasper always has access to optimized forage fed in a slow feeder (OptiMizer) and wears a grazing muzzle when there is a lot of grass. This management system helps him to maintain a body condition score (BCS) under seven.
In his day-to-day life Jasper tends to walk 5000-10,000 steps per day (tracked with a pedometer) as the paddock set-up is designed to encourage free movement. He also does lots of trail riding. Jasper’s routine veterinary care includes vaccinations, dental examinations, and fecal cell counts. De-worming needs are determined based on the fecal cell counts. His owner describes him as an easy keeper that is a content trail horse. Overall, Jasper has been in a management system that has a low risk of gastric ulcers.
Jasper’s 2022 Medical History
- May 13: Routine vet visit. Precautionary testing for pituitary pars intermedia dysfunction (PPID)—also commonly referred to as equine Cushing’s disease—due to owner’s concerns around coat condition and a few fatty lumps. The endogenous adrenocorticotropic hormone (ACTH) baseline result was 4.3 pmol/L, which is less than 6.6 pmol/L and therefore considered negative for PPID.
- July 21: Jasper presented with laminitis and was prescribed stall rest and phenylbutazone (bute). During this veterinarian visit, an endocrine profile was taken. His T4 was 31 nmol/L which is within the normal range of 13-40. His glucose was 4.3 nmol/L which is within the normal range of 3.7-6.7, and his insulin was 90 pmol/Lm which is below the normal cut-off of <300.
- July 25-August 4: Jasper’s symptoms abated and bute dosage was reduced and eventually stopped after the veterinarian assessment on August 4. At this time, Jasper returned to full turnout on a track system with hay fed in OptiMizers.
- August 21-26: Jasper was discovered in extreme distress with suspected colic. He was admitted to the Ontario Veterinary College – Health Sciences Center (OVC) for surgical removal of intraluminal bezoar in the proximal jejunum. This was major abdominal surgery with a large incision and dissection of the intestine that resulted in a long post operative plan of stall rest and a very slow re-introduction of forage.
- August 27: Jasper was off forage and seemed mildly colicky. His roughage was reduced based on veterinarian recommendations and a new (even slower) schedule recommended by the veterinarian was followed.
- August 28–September 13: Jasper was very hungry through this period as he was consuming only 20% of his usual daily forage that was metered out over six small meals. His portions were gradually increased daily. By September 14 Jasper was consuming 500g of pelleted mash twice daily and hay ad-lib but significantly restricted in an OptiMizer feeder with the smallest net size.
- September 14: Jasper presented in some distress in the morning. He kept lying down, was flank watching and off food. The veterinarian assessed and ruled out active colic. He was kept off forage for the day and observed. At 4 pm he was quivering, cold and seemed like he was going into shock. He was then admitted to OVC.
- September 15: He had a gastroscopic examination and was diagnosed with ESGD grade 2/4 and EDDG (moderate-severe). He was discharged on September 16 on medication and a new feeding schedule. During the gastroscopic examination, all regions of the stomach and the proximal duodenum were visualized. Therapy with gastroprotectants was initiated and after medication, a slow refeeding plan was started. The veterinarian communicated that the ulcers looked new.
- September 16–October 16: Jasper was prescribed Omeprazole for ESGD, sucralfate for ESGD and misoprostol for EGGD. His prescribed diet starting on September 16 was 3 kg pellet mash with 1 flake of hay, which was less than half his usual daily intake. It was instructed that this increase gradually to full ration at 50% pelleted mash, 50% grass hay plus hand grazing 20 minutes per day.
Jasper’s Management During Recovery
Jasper’s owner scheduled three visits per day (8am, 3pm and 10pm) to achieve medication administration and management requirements. During the morning visit Omeprazole was administered. After 30 minutes, Sucralfate was administered. After another 15 minutes, 1kg of pellet mash was fed, Misoprostol was administered, and hay refreshed in the OptiMizer. Jasper was also hand walked at least twice a day with a minimum five minutes of grazing each walk. He was very hungry over this period and became uncharacteristically difficult to handle.
See his detailed feeding schedule below:
|Amount per Feed|
(3 equal portions in OptiMizers)
|September 16||3||Over 4 meals||0.75||0.25|
|September 17||4||Over 6 meals||2||0.7|
|September 18||4||Over 6 meals||3||1.0|
|September 19||4||Over 6 meals||4||1.3|
|September 20||4||Over 6 meals||5||1.7|
|September 21||4||Over 6 meals||5||1.7|
On October 7, Jasper was scoped twice. Improvement was noted and the veterinarian comments that all of the lesions looked recent (likely since the abdominal surgery), with no evidence of old lesions. The detailed findings were:
- Mild scar tissue along the squamous portion of the margo plicatus in the greater less curvatures, and no other squamous ulceration was noted.
- A second gastroscopy was performed to evaluate the glandular stomach. The second gastroscopy revealed mild to moderate ulceration in the glandular portion of the stomach in the pylorus.
Until October 20, Jasper was maintained on stall rest for healing of his abdominal surgery in a large stall with forage being gradually increased to 10kg a day—2 x 1.5kg of pelleted mash and the rest was weighed hay in the OptiMizer supplemented two times per day.
November 4: Jasper was reintegrated with the herd in the paddock. Prescribed medication was continued for two more weeks. The owners noticed how out of condition Jasper was compared to the rest of the herd, although he quickly rebuilt some of his previous vigour on their track system.
November 26: First ride since August!
The Cost of EGUS
Jasper had an extremely complicated and expensive year. This cost summary is beginning on September 14 post abdominal surgery and all related to the EGUS.
|2022/09/14||Veterinary call on farm||$383.74|
|2022/09/16||2 days at OVC, endoscopy, ulcer diagnosis||$2,007.65|
|Vet Care: Sub Total||$2,718.18|
|September 16–October 17||Omeprazole||$745.85|
|September 16–November 18||Sucralfate||$523.02|
|September 16–November 18||Misoprostol||$1,295.00|
|Medications: Sub Total||$2,564.87|
|Total Cost of Ulcers||$5,283.05|
The above table breaks down the significant cost of diagnosing and treating EGUS. However, what cannot be quantified is the discomfort, pain, and stress our horses feel when health issues like this arise. Therefore, as horse owners who want the best for our horses, we should be ensuring that our management supports their needs.
Takeaway and Conclusion
Jasper’s prior management was low risk for any of the well researched risk factors for EGUS, such as intermittent fasting, low roughage, frequent travel, etc. However, following abdominal surgery which suddenly disrupted his trickle forage diet and possibly the administration of NSAIDs, he developed gastric ulcers.
Reducing the risk factors such as intermittent fasting by having forage continuously available within your management system can greatly reduce your horse’s risk of developing EGUS. The horses at Wishing Well Farm are fed from multiple hay OptiMizers. This allows the owners to ensure that the horses are never without hay. They have multiple feeders so that every animal can get to one and they are slow feeders to ensure the horses are still maintaining a healthy body condition. Slow feeding horses and ensuring their diet has adequate roughage greatly reduces the risk of them developing EGUS.
When reading how alarming, complicated, and expensive it is to diagnose, treat, and heal gastric ulcers. Why would any horse owner risk it by not allowing their horse to have continuous access to forage?
Cooper, J., & McGreevy, P. (2007). Stereotypic behaviour in the stabled horse: causes, effects and prevention without compromising horse welfare. The welfare of horses, 99-124.
Ninomiya, S., Kusunose, R., Sato, S., Terada, M., & Sugawara, K. (2004). Effects of feeding methods on eating frustration in stabled horses. Animal Science Journal, 75(5), 465-469.
Peters, S. M., Bleijenberg, E. H., van Dierendonck, M. C., van der Harst, J. E., & Spruijt, B. M. (2012). Characterization of anticipatory behaviour in domesticated horses (Equus caballus). Applied Animal Behaviour Science, 138(1-2), 60-69.
Zupan, M., Štuhec, I., & Jordan, D. (2020). The effect of an irregular feeding schedule on equine behavior. Journal of applied animal welfare science, 23(2), 156-163.Furness, J. B., Cottrell, J. J., & Bravo, D. M. (2015). Comparative gut physiology symposium: comparative physiology of digestion. Journal of animal science, 93(2), 485-491.