Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Puppies may eat less for a meal or two after a move, from stress, or while teething. But puppies have small energy reserves, so a puppy that refuses food for more than about 12–24 hours, or has vomiting, diarrhea, or lethargy, needs a vet. Toy breeds are at risk of low blood sugar, and unvaccinated puppies may have parvovirus.
Signs to watch
- Skipping meals
- Lethargy
- Vomiting or diarrhea
- Weakness or trembling (toy breeds)
Common causes
- Stress after adoption
- Teething discomfort
- Diet changes
- Intestinal parasites
- Parvovirus or other infections
- Swallowed objects causing a blockage
Go to a vet or emergency clinic right away if
- Vomiting and diarrhea in an unvaccinated puppy
- Weakness, trembling, or collapse
- Not eating for more than a day
- Swollen or painful belly
Safe home care while you arrange a visit
- Offer the usual food, warmed slightly or moistened
- Keep meals in a quiet spot
- For toy breeds that are weak, rub a little corn syrup on the gums while heading to the vet
What to avoid
- Frequent food switching
- Waiting overnight with a lethargic puppy
Can you ask a vet online about this?
Online vet services can be helpful for deciding how urgent a problem is, getting general advice, and follow-up questions. But they have limits:
- A vet can’t examine your puppy, listen to the heart and lungs, or run tests over video
- In many US states, a vet must have examined your puppy in person before prescribing medication. Rules vary by state and are changing
- For any emergency sign listed above, go directly to an emergency clinic rather than waiting for an online reply
Have your puppy’s age, weight, medications, and photos or video of the problem ready to make any consultation more useful.
Sources
- Merck Veterinary Manual: Care of puppies
- Ellis JA, et al. 2022 AAHA Canine Vaccination Guidelines. J Am Anim Hosp Assoc. 2022
- Merck Veterinary Manual: Canine parvovirus
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.