Two days ago, when I walked into the room where my 1 year old cat's litter box is kept, I noticed an odd, unpleasant odor (not ammonia). I thought it might be coming from the sewer pipes (ugh), so I ran the water at each faucet. A short while later I noticed a bad, not terribly dissimilar odor outside, so I chalked it up to the outdoor smell. (I haven't had a cat for about three decades, so I feel uncertain about what's normal in cats.)
The smell didn't go away, however; instead it intensified and smells exactly like mothballs. I remembered that about two weeks ago, I started mixing adult food with the kitten food, adding more bit by bit per day. He seems to really like the adult food and has tolerated it well, no diarrhea, and is acting completely normally. His abdomen is non-tender and not bloated.
The cat is a strictly indoor cat since I got him. He was treated for parasites when I first got him (his mother is a barn cat) and his stool was negative after treatment.
Today the smell is so bad that I have to hold my breath in that room despite running the exhaust fan continuously. The cat litter (Nature's Miracle corn cob litter) was changed ahead of schedule and it's helped a lot.
I googled it, and got a lot of hits. The causes listed were all over the place, from parasites to diet, as was the advice (from urgent vet visit to wait two weeks for the cat's gut to become accustomed to the new food and think about adding a probiotic. (Most of the info was written by vets, e.g. JustAnswer.) I don't know how he could have picked up a parasite being strictly an indoor cat. The dogs are fine and on monthly preventative.
Has anyone here had a similar situation? How serious is this? (Vet closed on weekends.)
Edited to add: There are not, nor has there been, any mothballs in by possession, nor anything that smells like them (I hate the smell.) The cat's food is the same brand as the kitten food. No change in the litter either.
