I left my cat in the care of a friend for a month and she fed him everyday. I guess she didn't want to clean the bowl because she put a paper bowl on top of the plastic bowl. When I lifted the paper bowl to clean the plastic bowl, I found mold and what I think to be fruit fly larvae in the old food. I don't think my cat ingested anything but I still think I should take him to the vet. My boyfriend says I shouldn't yet and see if anything develops. What do you guys think I should do?
There's no need to rush to the vet, unless one of the following occurs:
- Your cat gets diarrhea, vomits or refuses to eat or drink. "Vomit" means actually expelling eaten food, not just grass and/or hairballs (which is natural and healthy behavior for cats).
- Your cat gets lethargic, acts depressed, hides away or otherwise acts very different.
- Your cat coughs, wheezes or pants even while resting.
- Your cat has runny eyes and/or a runny nose for several days without improvement.
Most insect larvae are harmless to ingest and I doubt any made it through the paper bowl into the fresh food.
Mold could grow through the paper into the fresh food, if given enough time. Assuming the cat ate most of the fresh food most of the time, the mold didn't get enough time to infect the food.
However, you should probably discard the plastic bowl. Depending on its age and composition, there might be microscopic scratches in the surface, where the mold mycelium (the "roots" of the mold) can survive and infect the fresh food. A stainless steel, porcelain or glass bowl is more sanitary.
Cats are notoriously picky eaters. I don't really think you should be worried that your cat has eaten any food that would be unhealthy.
As a side note, cat senses were used (by my mother in law) for qualifying food for her kids - only the human food (sausages and other meat-based food) that were accepted by the cat were good enough for the kids. If the cat refused them, they were considered unfit for human consumption (the cat would refuse them if they smelled "off"). (That was in a time when cold chains for meat products - refrigeration during production, storage, transportation - were not always reliable, and availability of fresh food products was spotty - communist and early post-communist era).