Foam from the briddle- good or bad?

 

A debate I have seen on a few blogs lately, is the debate about foam created around the mouth, while riding your horse. There is alot of different opinions about this subject, whether or not it is a positive or negative thing.

One explanation:

The white foam is formed when the horse is sweating a lot, because of the protein latherin, which is also found in its saliva, and it probably helps to form the foam around the lips while riding with a bridle. The protein has a "soap-like" smooth consistency, and helps the horse to get rid of the heat, because it transports sweat all over the body when it overheats. This is the reason why the horse has a very good ability to thermoregulate at high temperatures.
"The Horse stands out not only in their ability to get rid of heat, which they of course must be able to do as large preyanimal but also in their ability to chew and digest dry food," says Malcolm W. Kennedy, Phd. evolutionary biologist from the University of Glasgow at The Horse. He believes that latherin also helped the ancient horses to survive on dry grass.
 
Latherin gets alot of extra attention because it may play a role in human allergic reaction to horses. A study has shown that equine allergic immune system reacts to the protein which is also known as allergen EQU c first.
- Source Thehorse.com 

Another explanation:
The drooling of frothy saliva at exercise is neither a virtue nor a vice; it is the physiological result of placing one or more foreign bodies (bits) in the mouth. Salivating is only one of a number of reflex responses that can be expected from such a step. The bit also breaks the otherwise airtight seal of the lips, admitting air into the oral cavity and, in the absence of food, allows the foamy saliva to escape. Apart from reflex salivation, other responses include movement of the lips, jaw, and tongue. Often the bit results in a mouth that is frankly open and a horse that makes occasional swallowing movements. All of these are normal digestive system responses. They are entirely appropriate in a horse that is feeding.

But if a horse is exercising, none of these responses are appropriate. For the deep breathing of exercise, an entirely opposite set of responses is required. The mouth should be shut and the lips sealed. There should be no air in the mouth and the mouth should be relatively dry, not wet. The jaw and tongue should be stationary in order that there is no interference with the airway from constant agitation of the soft palate and larynx. Finally, with regard to something that bit pressure is regrettably good at bringing about, the poll should not be strongly flexed, a position that further interferes with breathing.

From the above it can be seen that the bit method of control sets up a fundamental conflict. It confuses the exercising horse neurologically by stimulating inappropriate digestive system reflexes, and it seriously impairs breathing. Like ourselves, horses can either eat or exercise. They have not evolved to be capable of doing both at the same time. Drooling is an outward and visible sign that digestive system reflexes have been initiated. It is an inappropriate activity in an exercising horse. But the horse should not be blamed, for the fault lies with the method of control.

Personally I have noticed that most horses creates the foam while riding, but I consider it a negative thing when the horse has too much foam- meaning the front of the horse is "sprayed" with foam and alot of foam is comming out of the mouth. (like the above picture from http://www.hesteinternatet.dk/print.asp?id=3284) I see it as a sign of the horse being overworked and I often see this when horses are being hyperflexed and ridden behind the bridle for long periods of time, like the second explanation, saying that the horse should have a closed mouth while being exercised, when the horse is being hyperflexed it opens its mouth to release and get rid of some of the pressure from the bridle, and therefor it creates the foam.
A little foam around the mouth, I dont see anything wrong with, but it should be little and not a "flood".