I think you should definitely ask your vet about the stinky butt problem. It could be very well that it comes from the anal glends, it's not only a dog thing.

As far as Emily's gas problem goes, testing her stool for bacteria could help. Luna had a lot of gas as a kitten, and at the age of 9 months, e.coli have been found in her colon. It's been treated and she never had any gas since (well, except for the time when she had clostridia last year).

And btw, I don't think you could use Febreze (most likely toxic to cats), but would be interesting to know if there is a product like that for cats. But I think it's better to find out the cause of the stinky butts and remove it...

Kirsten