It’s hard to imagine that perhaps 25 years ago virtually no one had heard of gastric (stomach) ulcers in horses. Today it would be hard to find a horse owner who is not aware that horses can commonly suffer from gastric ulcers or equine gastric ulcer syndrome (EGUS) and that horses suffer from two primary types of ulcers (squamous and glandular) and that these have different causes (aetiology) and treatments. The definitive or “gold standard” method for diagnosing EGUS is gastroscopy; the passing of a tube with a camera on the end up the nose, down the oesophagus and into the stomach. The equipment is expensive. A “cheap” equine gastroscope is in the region of £10,000. And the procedure is likely to cost upwards of £200. If your horse is diagnosed with EGUS then the treatment is also going to not be cheap. It’s probably no wonder therefore that many horse owners look to supplements and the supplement companies haven’t been shy in producing them! But are they likely to help?
What to expect from a gastric ulcer supplement
It’s highly unlikely that any over the counter supplement is going to perform as well as licensed medications. However, that said, they may well work in combination with medication to give you a better response to veterinary treatment. But its going to depend on: 1) what ingredients are in the supplement and 2) the actual dose of each of those ingredients. For example, 1g of a buffer compound such as a Magnesium Hydroxide is going to have no effect.
Types of “gastric” supplement
Some supplements are purely aimed at gastric ulcers. Others are a “combination”, aimed at gastric ulcers and hindgut (large intestinal) support. Some companies are confused and use ingredients such as protected live yeast but then claim they are for helping gastric ulcers. Horses are big animals. The equivalent of a few antacid tablets are not going to have any effect. Neither is 10g a day of a combination of 10 different ingredients, irrespective of all the claims on the companies marketing extolling the virtues of each ingredient using phrases such as “known to be….” or “widely acknowledged as….” or “important for….”.
Types of gastric supplement ingredients
There are essentially going to be 4 different types of ingredients used in gastric ulcer supplements.
- Ingredients that raise stomach pH (make it less acid) – also known as buffers
- Ingredients that help coat the stomach to protect it
- Ingredients that supress acid-formation
- Ingredients that help promote repair of the stomach lining
Buffers
Buffers commonly include ingredients such as limestone (calcium carbonate), magnesium carbonate, magnesium hydroxide, marine algae, magnesium oxide and sodium bicarbonate. To have an effect on the horses’ stomach pH would require a dose of around 10-50g, depending on the specific compound. The ability of any compound to neutralise acid is determined by a combination of pKa (the higher the pKa the more alkaline a compound is and the more acid it can neutralise) and the amount fed. So for example, Magnesium oxide and magnesium hydroxide have a pKa of 15.7, whilst magnesium carbonate is only 6.1. So you would need to feed nearly 3x as much magnesium carbonate to have the same effect compared with magnesium oxide or magnesium hydroxide. Sodium bicarbonate has a pKa of 10.3 and is a moderately good buffer but does generate CO2 gas when mixed with stomach acid. Alfalfa is not a strong buffer unless it is the only source of forage.
Coating agents
A number of ingredients have been identified which coat the stomach surface and help to protect it either from ulceration or whilst ulcers are repaired. These include pectin (often from apple) and lecithin (usually from soya). Linseed is also a source of lecithin. Sucralfate is a medication used to coat and protect the stomach lining and is a complex of aluminium hydroxide and sulfated sucrose. Oil high in omega 3 (so not corn oil!) may offer some degree of protection to the stomach lining although this has not been conclusively proven.
Acid suppression
Omeprazole (GastroGard, Peptizole, etc) reduces acid secretion and the stomach pH becomes less acid. Very few supplements contain ingredients with any evidence that they reduce acid secretion. Some fruit extracts have been shown to reduce acid secretion (e.g. as used in GastroKind).
Repair
Ingredients that are often included which may have some impact on repair include Vitamin E, Vitamin C, a source of zinc, thioredoxin (from finely ground yeast), Sea Buckthorn and Aloe vera.
Take Home Message
- Look for a gastric ulcer supplement backed by clinical trials
- Read the list of ingredients – do they make sense in the context of this post?
- Avoid supplements with long lists of ingredients
- Look for companies that are totally transparent and give a full breakdown of each ingredient including the ACTUAL AMOUNT of each in g or units.
- If a supplement is going to help then the effect should be fairly quick. If it contains antacids and coating agents at an effective level then you may seen an effect shortly after feeding. If its based around acid suppression and repair then it could be 7-10 days before any effect is seen.
Here is a table produced in March 2020.
