Dog Vomiting Mucus

My dog vomited a yellow mucus like liquid with his kibble for a couple of days what could it be?
vomited his entire liquid croquette with that yellow mucus. wasn't croquettes were chewed over. their acts still healthy but do not know if anything else could be wrong
That is stomach acid. Sometimes, if a dog was not given any type of table food, you could be eating something you are not aware of, either inside or outside your home. When there is a buildup of acid in the stomach dogs is a good thing that throws up. Some adult dogs eat grass to help the stomach acid regurgitated. Once the acid is gone you'll realize that the dog will become very active and playful as it is relieved of his upset stomach. Just watch carfuly what your dog is eating. It is very possible that it could be something other than his dog food. Jackie