Puppy Not Eating: When It's a Concern

Puppies have proportionally higher energy and nutritional needs than adult dogs, given how much growing and developing their bodies are doing, which means an extended period of not eating carries more risk at this age. Small and toy breed puppies in particular are also at elevated risk of hypoglycemia (low blood sugar) when they skip meals, since their small body size gives them very little glucose reserve to draw on.

Common causes of appetite loss in puppies include the stress of a new home (very common in the first few days after adoption), teething discomfort, mild stomach upset, intestinal parasites, or in more concerning cases, viral infections. A puppy who skips one meal but is otherwise playful, drinking water, and has normal energy is a lower concern than one who's also lethargic, vomiting, or has diarrhea.

New puppy owners sometimes mistake normal adjustment-period pickiness (a puppy overwhelmed by a new environment) for a medical problem, and it's worth giving a very recently adopted puppy a day or so of grace while watching closely for other symptoms — but not much longer than that.

What to do: For a puppy who skips a meal or two in the first days after coming home but is otherwise energetic and drinking water, close monitoring is reasonable. Watch for weakness, trembling, or lethargy, which could indicate hypoglycemia and need faster attention, especially in small or toy breeds. Not eating for more than 24 hours at any age, or any combination with other symptoms, warrants a same-day vet call.

For more on how puppies decline faster than adult dogs and why that changes the calculus, here's a related look at puppy vomiting specifically.