Hypoglycemia (low blood sugar) may occur in puppies of toy breeds that have gone too long without eating compared to the energy they've expended. This depletes the body's stores of glycogen, and the brain, which is highly dependent on glucose, is one of the first systems to fail. The puppy becomes abnormally sleepy, weak and uncoordinated, to the point he may not even eat when offered food. If he doesn’t eat, the condition can progress to the point where the puppy has seizures, loses consciousness and dies. Toy puppies are especially at risk between 6 and 12 weeks of age, but the threat remains for many up to 7 months, and a few are susceptible even as adults. To avoid hypoglycemia, feed toy puppies frequently and keep them warm and quiet when they can't be fed often. Choose a good-quality commercial puppy food; there are even some puppy foods formulated specifically for small-breed dogs.