This is the single most common thing sitters message owners about, and it is usually the stress of an unfamiliar person rather than illness. Usually, but not always, and the difference matters a great deal depending on the species.
How long is too long is species-dependent
For rabbits and guinea pigs, not eating is an emergency within hours. For cats, going without food for more than a day or two carries a serious risk of liver complications. A healthy adult dog missing one meal is usually far less alarming. Follow the owner's written plan and their vet's advice, not a general rule.
The usual explanation
Animals notice their people are gone. Many respond by eating less for a day or two, particularly dogs who wait by the door and cats who spend the first evening under a bed. If the animal is otherwise bright, drinking, toileting normally and behaving as described, this is the most likely explanation.
What to try first
- Check you are doing it exactly as the owner described: same food, same bowl, same place, same time. Cats especially object to a moved bowl.
- Give them space. Many animals will not eat while being watched by someone new.
- Check the food itself is what it should be, and that nothing has gone off, particularly wet food in warm weather.
- Confirm they are drinking. Water intake matters more than food in the short term.
- Keep the routine steady rather than offering alternatives. Do not introduce new food to tempt them, which frequently causes stomach upset on top of the original problem.
- Message the owner. Early, before you are worried. They will know whether this is normal for their animal.
When it is not just stress
Treat it as more than settling-in if the animal is also lethargic or hiding more than described, vomiting or has diarrhoea, is not drinking, is straining in the tray or garden, has pale or discoloured gums, is breathing oddly, or is in evident pain. Any of those alongside not eating means contact the owner promptly and follow their veterinary plan.
For cats in particular, straining without producing urine is an emergency and should not wait. Our guide on cat urinary problems explains why.
What owners should leave
Tell the sitter what your animal's normal appetite looks like, whether it typically goes off food when you leave, how long you would consider acceptable, and at what point you want to be contacted. That single paragraph prevents both an unnecessary vet trip and a dangerous delay.
Also leave the written veterinary authority and spending limit set out in our emergency vet consent guide, because if this does turn into a vet visit, the sitter needs to be able to act.
This is general information, not veterinary advice. When in doubt, contact a vet.
