By Denise Steffanus Horsemen’s forums on the Internet abound with misinformation. One topic often discussed is daily feeding of sodium bicarbonate, or baking soda. Horsemen who train performance horses, and in particular racehorses, know that administering a large dose of sodium bicarbonate (about 18 ounces in a slurry of electrolytes, sugar, and water) can boost performance. Called a “milkshake,” it is given to a horse via nasogastric tube about six hours before a race to increase stamina by buffering lactic acid in muscles. Milkshakes are banned from racing, and trainers who use them suffer stiff penalties. But a segment of horsemen, both on the farm and on the racetrack, use a small amount of baking soda – one or two tablespoons – as a daily tonic. Reasons they give for doing this range from preventing a horse from tying up to improving the horse’s disposition. Warnings against its use include interference with digestion, colic, or sudden cardiac death. Few claims are true. Sodium bicarbonate is an alkalizing agent. When used on a daily basis, it is mixed in the horse’s feed or water. Most commonly, those who use it hope the baking soda will prevent ulcers by buffering acid in the horse’s digestive system, or help a horse get over the rigors of training by buffering lactic acid that accumulates in its muscles after a gallop or workout. Humans can identify lactic acid as the “burn” you feel when your muscles tire. Baking soda to buffer acid in the gut Dr. Joe Pagan, equine nutritionist and founder of Kentucky Equine Research, has studied the effects of sodium bicarbonate as a feed additive, particularly to treat hindgut acidosis by buffering excess acid in the large intestine. Horses suffering from hindgut acidosis may develop anorexia, colic, wood chewing, and stall weaving, all of which can contribute to weight loss and an unthrifty appearance. Prolonged acidosis may cause the intestines to lose their ability to absorb nutrients. Severe hindgut acidosis can cause laminitis. “There really isn’t much point to adding small amounts of baking soda in the feed,” Pagan said. “When you feed plain baking soda, it dissociates [breaks down] in the stomach, so you don’t get any buffering effect in the intestines. If you add it to water, it dissociates in the water. You supply some extra sodium to the horse, which may be okay, but you’re not really having much of an effect.” Pagan and his group devised a way to deliver sodium bicarbonate through the stomach to the hindgut by encapsulating it in layers of specially processed vegetable oil to help horses with hindgut acidosis. The product, EquiShure, is top-dressed on grain rations, with an 1,100-pound horse getting 50 to 100 grams (1.75 to 3.5 ounces) per day. Not only does it get the sodium bicarbonate where it provides the most benefit, the encapsulated product does not affect the horse’s total carbon dioxide (TCO2) level. “That’s what testing labs use to decide whether it’s a prohibited substance or not,” Pagan said. Baking soda in the stomach Sodium bicarbonate breaks down quickly in the stomach, and the carbon dioxide produced is rapidly absorbed into the blood as a buffer, raising the horse’s total carbon dioxide level. “The level in most states is 37 millimoles per liter,” Pagan said. “A normal horse is going to be about 31. When you give a couple of tablespoons of sodium bicarbonate, it’s probably not going to have much effect. TCO2 might go up one or two points.” But Pagan warned: “Lasix is an alkalizing agent that causes about a 2 millimoles per liter increase in TCO2. So, if a trainer were feeding plain baking soda and giving Lasix and a few other things, the horse could be close to getting a positive test. “Physiologically, feeding baking soda isn’t going to do any harm, but from a regulatory standpoint, it’s going to inch closer to a prohibited level, even when the horse is getting no real benefit. Bottom line: I wouldn’t recommend feeding plain baking soda.” Baking soda as an antacid Acid in the stomach helps digest food, so a common question is whether feeding a couple of tablespoons of baking soda with a grain meal or in water will interfere with digestion. Baking soda does buffer stomach acid, but it breaks down too quickly to interfere with digestion. And once the sodium bicarbonate breaks down, the stomach acid builds back up to its normal level. The rapid breakdown of sodium bicarbonate also makes it an ineffective antacid to guard the horse’s stomach against ulcers. “If you’re going to use any type of antacid, it has to have a longer-lasting effect,” Pagan said. “So, for that function, baking soda doesn’t do any good, but it doesn’t do any harm. If you’re trying to buffer acids that are produced in the stomach, calcium actually works better than sodium bicarbonate because it’s a slower release.” Pagan suggested feeding calcium-rich alfalfa hay. He referenced a Texas A&M University study that found feeding alfalfa reduced the incidence of gastric ulcers. But he cautioned, “Calcium is also a nutrient. Too much of it could potentially tie up other minerals and imbalance the diet.” Some horsemen feed baking soda to horses being treated with anti-inflammatory medications, such as phenylbutazone or Banamine, to protect the stomach from ulcers. Several veterinary sources said omeprazole (GastroGard) is the only proven way to protect the horse from ulcers when it is on a regimen of anti-inflammatories. Claims that feeding baking soda can cause colic or cure it are unfounded. Some horsemen conclude that because a horse cannot burp, gas from baking soda meeting stomach acid will cause colic. “Sodium bicarbonate will cause carbon dioxide in the stomach, but that’s being absorbed into the blood, not necessarily staying inside the stomach,” Pagan said. “If it were true, all these horses that are getting milkshaked would be blowing up.” Neither is baking soda effective as a colic tonic – an old remedy that combined Karo syrup, ginger, baking soda, and water as a drench. “Although this drench is very unlikely to be harmful, it would have too little effect to warrant having an owner try to give this,” said Dr. Anthony Blikslager, professor of equine surgery and gastroenterology at North Carolina State. If a horse appears to be colicking, call your veterinarian, follow his instructions, and only give medications on his advice, Blikslager advised. Prevents tying up, sore muscles Tying up (recurrent exertional rhabdomyolysis, or RER) occurs most often in fillies and nervous horses. Humans would call it a “Charley horse” in the muscle. Decades ago, when tying up wasn’t well understood, trainers would give a daily dose of baking soda to horses prone to tie up, thinking it would buffer the lactic acid knotting their muscles. Dr. Stephanie Valberg at the University of Minnesota is considered the leading authority on equine neuromuscular disease. She and her colleagues, including Pagan, tested this theory in 2003. They concluded, “Dietary supplementation with sodium bicarbonate at the concentration provided in this study [210 grams/day] appeared to have no beneficial effect on RER.” Valberg explained, “There is no evidence that horses develop exertional rhabdomyolysis due to a lactic acidosis ... so we cannot see a rational basis for feeding sodium bicarb to prevent tying up.” Lactic acid causes muscles to tire from exercise, and a large dose of sodium bicarbonate, as in milkshakes, can buffer that acid to increase stamina. But Dr. Ken McKeever at Rutgers University, whose 39-page résumé makes him a frequent expert witness on the subject, does not believe giving daily low doses of baking soda would be effective. He also explained that, even if a dose large enough to buffer the lactic acid in his muscles were given, the horse would not benefit. “That horse, as it’s training, needs to be presented with the challenges of exercise and then be able to adapt to those repeated challenges,” McKeever said. ”Lactate is something that goes up with intense exercise. The ability to tolerate lactate is in some camps referred to as ‘anaerobic power’ – the ability to generate a high amount of high-intensity work and be able to tolerate the metabolic consequences. So, if you repeatedly block the ability of that horse to go into a higher level of anaerobic metabolism, then you’re defeating its ability to develop the tolerance for more and more hard work.” He echoed Pagan’s warning to trainers about causing a bad test. “I would caution anyone that is going to give top-dressed bicarbonate in a horse’s feed that it doesn’t matter how that animal gets over the threshold – if it is pushed over the threshold, that’s a problem for the trainer.”