Rabbit suddenly eating less - normal or dangerous?

This is really not harmless - sudden loss of appetite in rabbits almost always points to a problem. These animals are masters at hiding illnesses, and by the time they're noticeably eating less, they've often had something going on for a while. Dental issues are super common, but digestive disorders, infections, or even stress could be behind it. The thing is: rabbits can't go without food for long, or their metabolism shifts and becomes critical.

My tip, which I don't see anywhere else - take a close look at the teeth. If the molars are too long, you often only notice it because the animal eats less or looks weird while chewing. Get yourself a good vet, and do it soon. Bring a stool sample too, so you can rule out something going wrong in the intestines. Until then: offer fresh hay (some rabbits prefer certain kinds), keep the environment stress-free, and watch whether water and stool amounts are normal. If there's no improvement in 24 hours, that's already a reason to go to the vet as an emergency.

You definitely need to take your rabbit to the vet, but don't panic - sometimes it really is just a temporary phase, like when the food doesn't taste good or the environment has stressed them out. The previous answers are right that rabbits hide illness, but that doesn't automatically mean something serious is going on! Check if your rabbit seems normal otherwise, if their droppings look okay, and if they're hopping around cheerfully - if so, it could just be a temporary loss of appetite. That said: give them a few days, and if the loss of appetite persists or other symptoms show up, the vet is definitely your go-to!