So, my sister has a new cat. He has incredibly stinky farts and when she gave him tuna his poop turned very soft and he tracked it around the house.
Is there something she can feed him that will make him stop farting so horribly? Is having a reaction like that to tuna an indication that Mr. Bill can’t handle his tuna or that there’s something wrong with him?
What does she normally feed him? (And yes, if she feeds him something and it gives him gross poop she should obviously not feed him that. It isn’t rocket science.)
Purina indoor cat chow - hard.
I would have thought it would have been common sense too but it also occurred to me that maybe the soft poop wasn’t caused by the tuna. Maybe it’s cause by whatever is causing the horrible farts.
She’s only had him 2 weeks so she’s not totally in tune with his health and habits.
We’ve gone through this before when adopting new cats. Some seem to need awhile to adjust to the diet their new person is feeding them. I imagine nerves could also be a factor.
I guess quite a few cats get a bit of upset from human (as opposed to cat food) tuna. I can’t stand the stuff so I don’t have much experience there.
Cats can be extremely sensitive to changes in their diet, setting, noises, etc. Changing a cat’s food suddenly from hard kibble to soft tuna was probably a shock to the cat’s system, on top of all the changes it’s undergone since arriving at the new home.
Purina cat chow is pretty much junk food. If you were fed mac ‘n’ chese all the time, you probably wouldn’t be all that fresh yourself! 
I’m not one of those cat food snobs (mine get Fancy Feast, which isn’t exactly haute cuisine itself) but if you’re going to feed the cat dry food, there are better brands that may have a better effect, digestively speaking. Nutro Max is a very good brand, as is Royal Canin and Solid Gold; the latter two are quite expensive, though. But Solid Gold is quite good for digestion.
The thing about better foods is that while they’re more expensive, in general they are much better for the cat’s system, and they won’t poop as often because more of it is utilized, nutritionally.
I am not a vet, however. If the cat’s having some issues, maybe your sister can get him or her taken to the vet to get checked.
Ooh before I forget: another tip is that if the cat seems especially nervous or is acting out (urinating/spraying, pooping outside the box, etc.), you might recommend your sister invest in something called Feliway Comfort Zone. It’s a plugin/diffuser that sprays odorless (to us) hormon that calms those little guys down. One of my cats was very anxious after she moved in and after I got the Feliway plugin, she chilled out. It doesn’t drug them or zone them out or anything… just seems to make them feel at home. Good stuff.
Not “hormon” (oy), I meant pheromone. Sorry.
Each time we get a new cat, New Kitty has an absolutely horrible case of gas that lasts for a week or two, and sometimes has a bit of diarrhea, too. It doesn’t seem to matter whether the cat appears to be adjusting well, either. My husband’s kitty, Charlie, was particularly bad, but even today Charlie occasionally lets out a really sulfurous toot. Some cats (and some dogs, too) are just naturally gassy. Others seem to adjust to their new living arrangements and are no stinkier than normal.
I get Prescription Diet, Intestinal from the vet. It’s not cheap, but it straightens that sort of stuff out. I had 2 cats that were pooping (literally) 5 pounds a day, but it fixed it up. Good for the gas too. Only needed it for about a month or so, until their systems got straightened out.