Blaming the dog is the oldest trick in the book.
But, if you’re sure it’s the dog …
Gassiness is usually a sign that the dog is eating something that he shouldn’t. If your dog is especially aromatic after his regular meals, consider changing his food. There might be an ingredient that the dog has an allergy or sensitivity to. Common problem foods for dogs are corn and wheat, but dogs can be sensitive to (or allergic to) any food, just as humans can.
To deal with the unpleasant symptoms, you can give the dog Gas-X or the generic equivalent (most dogs are not brand-conscious). It works!