Why do dogs throw up white foam and like they are having trouble breathe?

If Buddy is not eating or drinking...AND is lethargic. I would recommend getting him into see your veterinarian. Anytime our pets stop eating and drinking, it's time to seek professional assistance. Animals can get seriously dehydrated pretty quickly. Your veterinarian can assess his need for fluid replacement.

The white foam could be from excessive salivation due to nausea that he is swalloing. If he is having any coughing or gagging when he vomits this white foam...it could be signs of Kennel Cough. If Buddy has been in a keennel situation, daycare, groomers..even local parks, there is an oportunity for exposure.

Definately see your vet if these symptoms have continued...

All the best,