My EBT has also had bad gas and poo on kibble. I also switched to raw and the gas is better and the poo doesn't smell anymore. I don't know that I will every get rid of the gas completely because the breed is known for having it, but more specifically, I can't controle what he eats from the yard since some people in the neighborhood like to through stuff in my back yard!!Aren't boxers known for having gas? My EBT's were the same way with whatever food
I fed them until I switched them to raw. Now no more gas, or smelly poops.
The only thing I could suggest is, try changing the food, if that doesn't work then it might just be the dog.