We have a 5 month old Papillon puppy. We've had him for three weeks now. He just started having breathing problems such as wheezing, snorting difficulty breathing, etc. a couple of days ago, and we cannot figure out what might be the cause of it. Recently he started running and playing in our back yard where we now have a few weeds growing because of an abundance of Spring rains. We think his problem started when he started running around the yard and even may have eaten some sort of grass or weed in the yard. Not sure if this is the cause, but this is when the breathing problems started. We took him to the vet on Monday (March 12th) for a Well Check and his next shot. He was fine at the time. And he has now had all of his shots. The breathing problems started on Tuesday (March 13th). When he is calm and quiet just standing there or lying down he seems fine breathing through his nose and is fine. However when he is up walking or running and gets a little excited his breathing is labored and sounds like he is having an asthma attack and trouble swollowing. We live in North Texas. We gave him a dose of children's benadril. Not sure what else to do.