Why Is Dog Puking Mucus?

It depends what type of breed. If it is a small dog it would be normal because they are supposed to eat a full sized mean. If it is a medium dog it is worried of either its companion or its home and if it is a big dog you shall have to go to the vet because they should be able to  stop puking  mucus when they are a small dog.   Good luck. The reason I know this is because my dad is a vet.