Multiple times in my career I have had riders of other disciplines or people who have limited experience with horses watch a dressage horse being schooled. After watching they expressed dismay at the fact that the horse had foam on his or her lips within the work, stating that it was cruel and evidence of the horse’s discomfort and anxiety. This came as a surprise to me because when I am riding, having a bit of ‘lipstick’ as Trenna Atkins stated, is used by me as one of the markers of a successful ride. That being said, I do understand the aesthetic when viewed without an idea of what is happening ‘behind the bit’ can be alarming. Rabid dogs and poison victims spring to mind, and outside the dressage arena there are not too many instances of ‘happy foaming’.
But within the dressage arena the concept of foam acting as an indicator to a correct connection is very common. If I finish and my horse is completely dry mouthed, I note in my mind that something in the connection might not be quite right. That is because in true collection when the forehand pulls upward through the thoracic sling, an upward draw is also acted upon through the neck and into the poll. This upward/forward directionality is the mechanism that causes the horse to seek the bit, a staple of correct dressage. The horse should use his or her body out into the contact of the bit, seeking it without pushing through it. To read more on the mechanics of correct collection click here.
This action of the forehand into the neck cause the salivary glands to stimulate and produce more saliva, which then runs down into the mouth and is foamed by the movement of the lips and jaw. In a relaxed horse this will produce a small amount of foam around closed lips. Notice in this description I have said nothing of the bit. I believe that the presence of foam has nothing to do with the bit, but is actually a product of correct body mechanics and mental state. Take a look at this video of Uta Graef riding her stallion Le Noir in a bitless bridle (I realize that she is not wearing a helmet, and you all know I am very pro-helmet, but please refrain from commenting on that aspect. I think she is the bee’s knees and while a helmet would be icing on the cake, there are still so many beautiful positive things happening in this video that should be enjoyed.). You will notice that has the work continues, work that is very correct, so does the presence of the ‘lipstick’ in his mouth. The addition of the bit will merely cause the horse to “chew” at the contact and further encourage foaming.
With all of that understood, foam is only one indicator around which we discover the state of mind of the dressage horse. For example, if a horse is foaming at the mouth but his mouth is open and his tongue is purple, then though the foam might be present, it is obviously not an indicator of relaxation or a correct connection. The same rings true for a horse with a stiff back and wildly swishing tail who is pinning his ears and rolling his eyes. At that point you can pretty much cross of ‘supple connection’ from the list of positive traits. As well, though some horses may foam a bit more and some a bit less depending on the amount of saliva their bodies produce, copious amount of foam spraying everywhere is not a good thing. If I saw a horse foaming buckets, I would be taking a close look at the state of his jaw, back, tail, etc. before assuming that all is well in the world.
My point being, foam is a product of a correct body independent of the bit. The bit can then positively or negatively affect the state of the horse’s mouth. On the other side of the spectrum is the dry mouthed horse. Again, I would be looking at the whole body before assuming that anything is positive or negative, but with correct dressage training I would want to encourage that upward draw through the forehand more and more, encouraging that ‘lipstick’.
Those from other disciplines do not ask for the same physical ‘shape’ as dressage. A western pleasure horse moves in a very different shape from traditional dressage horse who is different from a grazing horse. Additionally, other disciplines have different relationships to their horses and the bit. While traditional dressage horses ride into the connection, other disciplines might ride with a looped rein almost exclusively. These differences in the connection coupled with the criteria of each sport regarding the body shape of the horse will then create a multiple ‘pictures’ and different relationships to the salivary mechanism. If the horse is never asked to use his topline into his neck into his poll then the salivary glands will not produce saliva in the same way, which will then not work into the mouth in the same way.
Unfortunately the world of dressage is more complicated than saying – “Foam Bad, Dry Mouth Good” or “Foam Good, Dry Mouth Bad”. One must train their eye to take in what is happening through the body and whether the tension in the horse is positive muscular tension or negative mental tension. But to reiterate, foam in the mouth is not a negative trait and in fact can be a very positive one, if you understand the body processes behind it.