Baking soda is doing the rounds as a homemade treatment for horses with gastric ulcers. Baking soda or sodium bicarbonate also known as bicarbonate of soda, is a chemical compound with the formula NaHCO₃. It consists of bicarbonate and sodium. Why would this be suggested for horses with gastric ulcers? The stomach is an acidic environment due to the release of hydrochloric acid (HCl) into the stomach to start digestion and also to kill microbes including bacteria, moulds and viruses that may be ingested with food. However, acid splashing up onto the upper part of the stomach during exercise can lead to squamous ulcers. Squamous refers to the region of the upper part of the stomach which is comprised of squamous epithelium. “Acid splash” is particularly likely to be a problem when horses exercise on an empty stomach.
So what is the rationale for adding baking soda to horses feeds? Baking soda is a “buffer”. Its alkaline (the opposite of acid) and so has the ability to balance or neutralise or buffer acids. Reducing the acidity (increasing the pH) can allow ulcers in the squamous region of the stomach to heal. The pH of the stomach juices are very low – around 1 to 2, which means the acid is actually very strong. Reducing acidity is the mechanism behind drugs such as omeprazole used to treat both equine (Gastrogard® and Ulcergard®) and human gastric ulcers and gastric reflux in people – remember horses are unable to experience gastric reflux due to their stomach anatomy.
Baking soda is cheap and you will also see it appear on the label of many “gastric” supplements. But can it really reduce acidity and help heal ulcers? Is it really an alternative to omeprazole?
Equine stomach acid is hydrochloric acid (HCl) and with a molarity (strength) of around 0.2M and a pH of ~2 (Acid).
A 0.2M solution of sodium bicarbonate (baking soda/NaHCO3) will have a pH of around 9.2 (Alkali).
Mixing the two together will result in the rapid production of water, carbon dioxide and sodium chloride> NaHCO3 + HCl → NaCl + CO2 + H2O
If we assumed 2 litres of 0.2M HCl in the stomach, then adding 35g sodium bicarbonate should have a rapid, if transient effect on stomach pH but little or no effect on blood pH.
So sodium bicarbonate (baking soda) is a moderately effective buffer, although there are better ones, such as magnesium hydroxide. The problems are that baking soda doesn’t taste very nice and the effect on stomach acid is short-lived. So to be effective, you may need to give your horse 35g perhaps hourly. Not very practical. This is where omeprazole has the advantage, as daily dosing reduces stomach acidity long term.
The Bottom Line
Giving your horse 35g (~16ml or 3 x 5ml teaspoons) in a feed is not going to do any harm, but it may not be palatable. On the other hand, it won’t be effective unless you are giving it every few hours. The best option would be to give it just before exercise, although you would also likely get more benefit in reducing the risk of squamous ulcers by ensuring your horse had forage before exercise of a meal of chaff.
