white foam in nostril

Question

foam white   hello Lyn. are you able to figure out white foam in the left nostril of the horse right below the shadow roll? what can it be?

Answer
Rohit,

If coming from only 1 nostril and not yellowish or foul smelling I sort of suspect a mild allergic reaction.  Could be something the horse inhaled with the hay that irritated the lining of the nasal cavity.  Horse's can't blow their noses into tissues like we can so if they snort something out or experience a bit of sinus drainage unless you wipe it for them (I do regularly) you will see this.  Unless it lasts for a long time, I wouldn't worry much about it.