How to convince my mother to adopt a cat.

how did you get your cat potty (litter box?) trained?

Litter training is generally pain-free and simple. Give a cat a place to dig and bury poop, and they'll catch on fast. If you place another cat's poop in the box, or the cat's own poop, you can show them what it's for. I've never seen it take more than that for any cat I've had. Even wild feral cats grasp the function of a litter box once you drop a load in there.

As far as peeing about the house, once they're fixed, that's fixed.

Beyond the initial expense of spay/neuter + vet checkup - maybe $100-150? - there's hopefully only the yearly vet checkup, which aren't pricey. I pay like $70 for my cats' yearly checkup. That's for two cats though, for a single cat my vet charges only $45.

Food expenses for a single cat will be minor, even if you spring for premium food. There's only so much a sub-20lb creature can eat. If you have multiple cats, then it can get a bit expensive. Though it's only $70/month to feed my two fat cats, really not that bad. Fancy Feast canned food is very inexpensive, and a couple varieties have decent ingredients. It would cost like $10-20 at most per month for that stuff. Maybe $30-40/month if you spring for premium stuff, but even Fancy Feast is better than any $5 dry food.

I spend $40/month on litter, so for a single cat that would definitely halve.

Really, unless you're handling multiple pets, it should be an affordable venture. If you keep the cat indoors, you've virtually eliminated the need for any meds/treatments for fleas, etc., and would mean a safer life for the cat, meaning less potential for vet expenses.

Also you could probably save on spay/neuter costs by adopting a rescue.

/r/cats Thread