Sometimes — with care
Apple flesh is a safe TREAT for rabbits — emphasis on treat. Seeds are mildly toxic and the sugar content means small, occasional portions.
Rabbits love apple, and a small piece is a useful bonding treat or medication-hider. But fruit sugar disrupts the delicate fermentation in a rabbit’s cecum if overdone, contributing to obesity, soft stools and gut imbalance. Apple seeds contain amygdalin (cyanide-releasing when chewed) — a few seeds are unlikely to poison a rabbit, but they’re trivially easy to remove, so remove them. Stems too. Skin is fine.
A thumb-sized slice once or twice a week for an adult rabbit, as part of a fruit allowance of 1–2 tablespoons per 2 kg total (all fruits combined). No fruit for babies under 12 weeks, overweight rabbits, or rabbits with a history of soft stools.
Herbs feel like treats without sugar: a sprig of parsley, basil or mint usually delights just as much.
This article is general information, not veterinary advice. If your pet has eaten something potentially harmful or shows symptoms, contact your vet or an emergency clinic immediately. Full disclaimer.