Sandra moved to Maine four years ago with her two horses. On my first visit to her farm she told me that her older gelding, Benny, had a history of belly aches. I asked what he was getting to eat. She said he gets about ¾ of a bale of hay and 2 pounds of low carb grain a day. That seemed about right for this 900 lb. Morgan. Our conversation was taking place as we stood outside Benny’s stall. Sandra moved a little closer to me and said in an awed whisper:
“The thing is, Benny likes to eat.” She paused, and then, “He really likes to eat!” I questioned what she meant.
“I mean he plows right into it and his head doesn’t come up until he has eaten every little scrid! I start with hay so he won’t choke on the grain, but, I kid you not, hay and grain are all done within 20 minutes. He just scarfs it down! He seems fine, I leave for work, and more than a few times I’ve found him colicky when I get home. Do you think it could be worms?”
I told Sandra that Benny’s problem was probably not worms. Morgans do like to eat, and Benny was more than true to the breed. I thought that the real problem was that most of the day he wasn’t eating. Sandra would leave for work, and there was Benny in an empty stall or paddock with nothing to eat. He had already had enough, but not in a healthy way. Part of the reason for the colics was his lack of saliva. How did I come up with that? Would learning about saliva change anything that Sandra or that you might be doing? Estimates on how much saliva horses secrete run between 3 and 15 gallons per day for a 1000 pound horse. That’s quite a range. That’s because the amount is dependent on how they are fed. What does that mean?
In all animals saliva moistens and softens the food and then eases its passage down the esophagus and into the stomach. Most of saliva (99 % +) is water. It also contains some buffering compounds like sodium bicarbonate which are helpful in counteracting acid in the stomach. Saliva is nature’s anti acid. It also contains enzymes which help break down food into simpler and more digestible forms. Saliva gets its slipperiness from a lubricant called mucin. Even that is important. Every time I do a physical on a horse, I run a finger into his mouth and then rub my finger and thumb together and smell it. It should smell clean and be slippery. Saliva that is tacky or has an off odor means you are looking at a horse that isn’t right.
There are 3 paired glands that produce saliva in horses. The major ones are just under the skin behind the jaw and between the jaw bones. The saliva is carried by tubes, called ducts. They open into the mouth. You can spot one set of them if you open your horse’s mouth and move the tongue aside. Just a couple of inches back from the lower jaw incisors, right where the tongue usually nestles, you can see a pair of tiny flaps that cover two of the duct openings. They glands start secreting when a horse starts eating, and the flow slows down when the chewing stops. Nothing in the mouth means no chewing and very scant saliva. This is unlike you and me, who before, during, and after meals are continuously secreting saliva. Our mouths are always wet. Horses not so much unless they are eating.
With this knowledge we are prepared to explore the how of horse feeding. Researchers sitting on the ground out west with their laptops and timers have found that wild horses spend at least 85% of their standing time doing one thing. Their heads are down and they are eating. That horse on the prairie, eating almost continuously, is always producing and secreting saliva. Not true for Benny and many of our domestic horses. Ask your vet how many colics he or she sees in a year. Colic is extremely rare in wild horses.
When you leave for work like Sandra and throw a few slices of hay into a paddock or stall, there may be hours when the food is gone and the mouth is empty. An empty equine mouth means a relatively dry mouth because there is nothing to stimulate the saliva flow. The stomach has no food to work on, and nothing much to buffer the acid. It adds up to a perfect ulcer scenario.
Years ago in my race track practice I daily saw horses standing in their stalls with nothing to do, waiting for their next meal. Heavy grain and a few slices of hay 2 times a day was the diet. Hopefully that has changed, but horse traditions die hard. Diets low in roughage and high in grain don’t produce enough saliva to neutralize stomach acids. Studies verify that 90% of race horses have ulcers.
Whenever possible feed minimum amounts of grain and make roughage continuously available. I tell owners that when feeding time comes around again there should be enough hay in their stall or paddock so that a bird could build a nest. If you have a particularly easy keeper, you may have to feed less leafy hay, but don’t, please don’t, leave them for hours without something to chew on.
When I talk about continuous roughage, I get push back from owners who are tired of throwing away hay that has been pooped on and walked over. Today’s hay nets are an effective answer to that problem. They are the closest thing to turning a horse out on acres of grass. Some nets hold an entire bale. I like the nets with a tight weave so that each bit of hay has to be teased out. It keeps horses occupied and insures roughage in the stomach You can jam the nets full and leave them right on the ground or on the stall floor. A side benefit is that horses are at their most relaxed when their heads are down and they are eating. As they chew the saliva flows, the stomach has something to work on, and ulcers are minimized.
To summarize: Saliva is important for digestive health. Constant intake of roughage keeps it flowing. It is better than any purchased supplement for the prevention of ulcers, choke, and colic.
PS. Sandra changed her feeding routine. Benny is now fed from a hay net. By the time Sandra gets home the net is pretty flat, but there is always a little left. He has not colicked in the last four years.
PPS. For a different look at saliva, see an earlier article in this series about horses who salivate too much, entitled “The Slobbers.”