No, cats are obligate carnivores and my cat's poor tummy is so sensitive she has to have special biscuits so that's not something I'd be willing to risk. Plus technically she's my parents' cat so it's their choice.
Dogs do better on a vegan diet but this is my diet choice. I don't know what I'd do if I had a dog. Maybe if I got them from a puppy I'd think about it.
Re: the gas - it's really common and it will pass, if you'll pardon the pun.
Just a thought, have you eaten a lot of beans / lentils etc? Because that can definitely contribute to it. After 6 years I'm used it so don't get affected that way very often anymore.