Last Updated on March 18, 2022 by Allison Price
Gastric ulcers and Thoroughbreds are like ants and picnics. Omeprazole, a medication that can treat or prevent gastric cancer, is very popular in the racing world. It also has significant welfare benefits. Some potential drawbacks to omeprazole could make it less effective in certain cases.
Between 80-100% of Thoroughbreds have stomach ulcers in their squamous (upper) region. Another 10-60% of Thoroughbreds are also affected by gastric ulcers in their glandular (lower) stomachs (equine gastrotric glandular disease (EGGD).
Horse discomfort can be caused by ulcers. These are stomach lining erosions. Gastric ulceration can manifest in a variety of ways, including a dull coat, weight loss, bruxism, poor performance, and weight gain.
Management practices can cause squamous ulcer disease. This is not limited to Thoroughbreds. “High intensity work or prolonged periods of work that involves high intake of high carbohydrate, high protein, and low roughage will increase the risk of developing this disease,” Dr. Ben Sykes, Equine Clinic, Massey University New Zealand, said.
Although they are safe for short periods at label doses, medications like phenylbutazone (commonly called “bute”) and other non-steroidal-anti-inflammatory drugs (NSAIDs), can also cause or worsen gastric ulcer disease.
Various medications have been developed to manage EGUS in order to maximize the welfare, performance, health and welfare of Thoroughbreds. To prevent further damage and healing, sucralfate is applied to the ulcers. Ranitidine and Omeprazole reduce the acidity in the gastric juice. Misoprostol protects and preserves the linings of the glandular mucosa.
Most commercial omeprazole preparations recommend that ulcers be treated with 4 mg/kg daily for four weeks. Horses can be treated for longer periods at a lower dose to prevent gastric ulceration from recurring. This is usually 1 to 2 mg/kg per days.
Omeprazole is not always a good choice. Omeprazole’s long-term safety has not been proven. This is in addition to the fact it can be costly to administer long-term. It may also not be as harmless as you might think, even if it is used for a short time.
Sykes has shared four main concerns about omeprazole administration in a recent article published in the journal Equine Veterinary Education.
- Rebound gastric acidity. The gastric contents could become more acidic after abruptly stopping omeprazole. This may lead to rapid recurrences of ulcers in horses.
- Changes to the fecal microbiome. Any medication can negatively affect the health of horses by affecting the population of microorganisms that live in the equine hindgut. Omeprazole doesn’t appear to alter the microbiome within 28 days, but long-term effects are still being studied.
- Interaction with NSAIDs . Gastric ulcers can be caused by bute or other NSAIDs. Many horses who have been treated with these drugs receive omeprazole.Sykes stated that while omeprazole can prevent gastric ulcers that could be caused by NSAIDs (a recent study has shown that this combination may cause small intestinal issues such as colon impactions or diarrhea that can prove fatal), especially when high doses phenylbutazone have been used. My current recommendation is to not co-administer NSAIDs with omeprazole or to use the lowest possible dose for both drugs. Suprafate may be an option if there are still concerns about the possibility of NSAIDs like bute causing gastric ulcers in a patient.
- Fracture risk increases . Omeprazole administration in humans is associated with an increased risk of fractures, in both the geriatric population and in the juvenile population.Sykes stated that there is no evidence to suggest that omeprazole causes a similar effect in horses. Sykes stated that studies looking at the effects of omeprazole short-term on bone metabolism did not find any effect. However, there are data from horses showing that the pathways that lead to fracture risk in humans can also be found in horses when omeprazole is administered in short-term.Given the importance of fracture risk within the racehorse sector, long-term data are needed but they are not available.
Omeprazole, which is widely used for EGUS in horses both short-term and long-term, has a good safety record, but it may also be associated with some important safety concerns.
Sykes stated that omeprazole “has a high safety profile but does not necessarily mean that omeprazole can be used in all situations.”
In an ideal world, owners, trainers, and veterinarians would try to use the lowest dose of omeprazole possible that maximizes results.
Syke stated that optimizing absorption would help us get more bangfor our buck. Fasting overnight before giving omeprazole to horses will make it more absorbable than if they had been fed. If the horse has not fasted, we will only need to give half of the drug to get the same level in acid suppression.
We all know that horses need hay to be able to manage their EGUS. Do we need to worry about withholding hay for the night? Sykes said no.
Horses don’t eat overnight, even if they are fed ad libitum. He said that they instead spend their time sleeping or resting.
Sykes suggested the following tips to use omeprazole safely and effectively based on current information:
- Horses that are fast overnight. By 10 p.m., take away the horse’s feed
- Before you feed or exercise, take omeprazole in the morning. Peak absorption from the gastrointestinal tract to the circulation takes around 60 minutes. The horse should not be fed for at least 30-60 minutes after administration.
- Begin treating horses with 2 mg/kg of omeprazole daily. If necessary, increase the dose to 4mg/kg (based on clinical response or gastroscopy–direct visual inspection of the stomach with a scope by a veterinarian).
- Other medications can be administered for gastric ulcers that are not related to omeprazole.
Sucralfate and ranitidine should not be taken with omeprazole. Sykes explained that these medications can interfere with the action of Omeprazole, and that the pH of the stomach contents won’t rise as expected.”
These other medications can instead be administered during feeding, 30-60 minutes after omeprazole administration or in the afternoon. Omeprazole is only given once per day in the morning.
Sykes stated that exercising after omeprazole administration, and even feeding, can increase the effectiveness of omeprazole. This is because exercise causes the most damage to the stomach’s squamous mucosa.
Sykes stated that while owners shouldn’t be discouraged from using omeprazole but should be aware of the safety concerns.
He said that omeprazole should be taken in safety and responsibly, as with all prescription medications. The recommended management changes along with administration will allow for comparable or better treatment results and better outcomes at lower doses of omeprazole. This will not only provide financial benefits, but it will also improve the drug’s safety profile and allow for the use of the lowest dose.
