Saliva: Horse’s First Line of Defense Against Ulcers

IT HAS ONE JOB: ACTIVATE!

All mammals secrete saliva to activate the digestive process, and the job of saliva is contingent on the species-specific diet composition and the needs of both the foregut and hindgut. 

THAT’S A LOT OF SPIT

Compared to carnivores and omnivores, equine saliva is 99% water with high levels of calcium and chloride and has virtually no digestive enzymes. Since horse saliva is mainly comprised of water, it is no wonder that horses drink 10 -12 gallons per day on average and produce 9-11 gallons of saliva per day. It’s almost a wash when comparing water intake vs saliva production, with water barely winning.  

To better understand saliva and how it benefits horses, it’s important to look at the complete digestive process as a whole. Watching a horse out on pasture shows us all the steps required to initiate the saliva excretion. It all begins with the lips, acting as sorters. From there, the food is sheared off with the incisors, the tongue moves the dry matter to the molars, and the mastication begins. Here, food mixes with the newly excreted saliva to act as a lubricating agent for chewed food to pass through the esophagus and to provide a buffering antacid to the stomach acid.

LIKE A BAD NEIGHBOR, STOMACH ACID IS ALWAYS THERE

One of the most interesting facts about equine saliva is that, unlike humans, horses do not produce saliva continuously. Production of saliva begins when they chew and ends when their meal is done. However, they produce stomach acid on a constant basis, and not just as a response to the presence of food. This is a key point that every horse person should know. In order for the saliva to do its job, it is critical to balance the never-ending production of stomach acid with enough forage to keep the horse comfortable, healthy, and possibly ulcer-free.

The balancing act of water intake, saliva excretion, and forage ingestion can quickly spin out of control if water and forage are not readily available for 16-18 hours a day. This is usually not a problem for horses on pasture. Water content in pasture is significantly higher than in hay, and when continuous grazing is allowed, the saliva production is in full gear.

Maintaining a homeostatic gastric environment becomes problematic when horses are not on pasture grazing the majority of the day. Therefore, it is our responsibility to give the horse what it needs. The best way to set a horse up for digestive success is with enough forage available throughout the day and night. 

ACIDITY OPENS THE DOOR TO ULCERS

Chemistry comes into play here. A pH numeric scale measures the acidity or basicity of solutions. The scale is normally 0-14, with 7 being neutral. Acid = 0-6 and Base = 8-14. The pH of the stomach fluctuates based on its contents. Both the amount and type of feed and forage affect the pH level. The range of pH readings has been recorded from 2-6, so even in the best-case scenario, the equine stomach is an acidic environment.

Saliva directly impacts the health of the stomach lining by reducing the stomach’s acidity. This natural buffer neutralizes the acid, thus protecting the stomach wall, and helps keep ulcers from forming. When this layer of protection is disabled due to inadequate forage intake, the stomach lining suffers, which results in erosion and ulceration.

EXERCISE CREATES EVEN MORE ACID

Seems twisted, right? How can something good for the body also be detrimental? Researchers have discovered that exercise increases the production of gastric acid while decreasing blood flow to the GI tract. To make matters worse, when horses exercise, the acidic fluid in the stomach splashes and exposes the upper, more vulnerable portion of the stomach to an acidic pH. Exercise is a definitive culprit for ulcer formation. It is believed that at least 50%, and as many as 90%, of performance horses are affected by ulcers. 

IT’S ALL ABOUT THE CHEW

To keep the stomach lining bathed with buffering saliva, remember it’s all about the chew time. Horses need to chew 55,000 - 60,000 cycles (sweeps) per day to keep the saliva flowing. 

Here are suggestions to help achieve this:

• Offer chopped alfalfa with your balancer or concentrate. This lengthens the chew time, thus increasing the amount of saliva. 

• Offer multiple meals throughout the day to keep the saliva excretion in motion.

• Prior to exercising, offer alfalfa (known for its natural calcium acting as a buffer) 30 minutes before you begin. Having freshly chewed forage, sitting on top of the acid, allows it to act as a “forage mat” and help prevent the acid from splashing the unprotected area of the stomach. 

• If pasture-fed, rotate pastures to ensure the forage amount is met. A busy horse “grazing” is not the same as a horse actively eating an adequate amount of forage. 

• Utilize enrichment tools that make it fun and interesting to eat forage while slowing down overall intake. This is great for horses on dry lots, stabled horses, or when pastures need supplemental forage. These tools range in type, size, and style depending on what is needed for your nutritional goals.

KNOW BETTER, DO BETTER

As most of us know, equine ulcers are much more complex than just controlling nutrition. There are a whole host of ways ulcers can become prevalent, and a lack of saliva production is just one way. Education is the golden ticket that can have a significant impact on our horses’ digestive health, which directly affects their overall physical and mental well-being. Nurturing this holistic approach allows a more natural balance between man and beast and creates a place where we both can thrive.