What is causing the dog to throw up?

If the dog throws up only certain food, then stop serving him that food. If the dog throws up all food and the vomiting doesn't pass within 12-24 hours (make sure dog has access to plenty of water),...

sometimes if they eat them they might if they get sick to their stomach!!

Take him to the vet as they get different types-some can be very serious like heartworm.

Take the dog outside and rub (very gently) on its back and say you're ok..

you can make a dog throw up by feeding it unnesssary things like crayons etc.. my dog ate crayons and threw it up.