I often get asked about what it means when a horse has foam in their mouth and whether it is good or bad. My answer is: It depends.
Causes of Foam
In general, foam is created by saliva + mouth movement and can be formed in times of calm concentration or stress
Degrees Of Foaminess
Lipstick: A small bit of foam where the lips meet
Mouthful: Foam everywhere in the mouth
Whipped Cream Machine: It's everywhere, dripping out of the mouth and all over the chest
Built For Bubbles
A horse's saliva contains something called Latherin which is a surfactant and helps them chew and digest dry forage. It is also found in their sweat and is involved in thermoregulation. That is a chemical reason for a horse's ability to create lather and foam.
I am not sure if this happens in horses, but with humans (and I have experienced this when running) saliva becomes more viscous during more strenuous exercise.
Good Or Bad?
There are many ideas and opinions out there about why horses foam and whether it is 'good' or 'bad'. Below are my thoughts on the subject, based only on my personal observations and experience.
Foam Of Concentration
Solana with Foam Of Concentration after a lovely riding moment in a bitless bridle. Soon after this photo was taken she licked it away as a result of her calm state of mind and relaxed mouth and jaw. (My dog is hoping I drop a horse cookie 🤣)
Foam Of Concentration often shows up as lipstick foam. When horses are super focused and keeping their mouth softly closed, the gentle friction of their lips softly touching will create a rim of white foam. Some will say this type of foam is always desirable and will only happen when a horse is moving correctly through his back, but I'm not so sure about that.
A horse with lipstick foam that is not in a moment of moving with a relaxed topline or harmonious contact.
Some horses may show a mouthful of foam, particularly when ridden with a bit. A mouthful of foam could be due to stress, especially if it shows up even during physically easy moments. However, it may instead be a result of concentration, a relaxed jaw that is softly moving, increased viscosity of the saliva during exertion, and the bit providing one more surface to move and create lather.
Foam of concentration often disappears quickly when seen in calmer horses. When a calm horse is given a break during exercise, he or she will move their mouth and lick it up... Of course, this only applies to what they can reach with their tongues if, indeed their mouths are unrestricted enough to move to that degree.
I observe many horses who produce more than lipstick foam want to get rid of it by rubbing it on their legs. Unfortunately, many horses (especially those wearing double bridles) are not allowed to reach down and rub it off because the curb chain hook could get caught on boots or wraps... So, foam remains. I wonder how frustrating that is to the horse?
Foam Of Stress
A horse with a mouthful of foam
Foam of stress can show up as Lipstick, a Mouthful, or a full-on Whipped Cream Machine. Foam of stress often stays. A tense horse who doesn't lick and chew, or whose noseband is too tight to allow that may have lingering foam. (See this blog about nosebands).
Another reason foam may be persistently present in larger amounts is if the horse is not swallowing. This could be due to stress, learned helplessness, and/or lack of ability to move their mouth and tongue due to an excessively tight noseband.
It's Not About The Foam
There are some that are so convinced that all foam is good, that they will go to extreme measures to create foam. I have known people to put liquid soap in their horse's mouths prior to entering the dressage competition arena.
Talk about leaving a bad taste in their horse's mouths! 😳 🤮
No Foam - Good Or Bad?
Some stressed horses will show no foam if their mouths are dry due to the contact pulling the lips apart and the mouth opening.
A stressed looking horse with open mouth showing no foam.
Some horses rarely show foam (or it disappears quickly) when going very well because they are able to lick it up as quickly as it forms, even during movement. This can only happen with horses who have no restriction to their mouth movement and are calm enough to lick and move their mouths during exertion.
Moments of Solana licking while being ridden. She is in a bitless 'double bridle' which is the DN bitless bridle plus a curb. The bitless bridle is designed to be able to have a very loose noseband. You will see she has plenty of room to give a full extension of the tongue.
How To Use This Information
My best advice is to know your horse and observe when things change. Does he usually froth profusely, then during a certain ride there is much less foam? Does he usually not foam, but then one day he has a mouthful?
Take a moment to think about the whole ride. What was his mental/emotional state? How were his balance, contact, and overall performance? What else was different? This will give you a clue as to whether this change in his foam status was indicative of a positive or negative situation that you will want to remedy or repeat!
Thoughts? Leave a comment below!
