How do you feed your pet a wellness treat?

I often let my pet owning sims have a table or shelf where they store those wellness treats. I put most of them in the main sim's inventory, but by keeping this spare storage, they are also available to other household members (in case main pet person is away) + I avoid running out because I see when it's time to visit a vet to restock.

I'd prefer if we could turn off the pet sickness though. I don't mind them being sick, but the visuals do easily ruin any story telling, stealing my gaming time because I need to remove that red glowing nose or legs etc.