Topper was diagnosed with asthma his last couple of years but only had one bad attack, brought on by cold weather. by the time we got to the emergency vet he had recovered pretty well, but his oxygen level was still very low. He was already on theophylline and lasix for heart/lung issues that were 'normal, ongoing', not 'attack-like' so he stayed on that. The Internist said that inhalers are difficult for dogs, getting them to inhale just as you puff it is almost impossible. One vet had us use a small compressor to give him albuterol treatments, I would just hold it and aim it at his nose. The other option was to put him in a small plastic crate, drape a towel over it and have the atomized medicine fill the 'tent'. Neither really worked very well, and I think the stress outweighed the benefits. We were fortunate that his severe difficulty breathing and wheezing only happened the one time.