Hypoglycemia is a common ailment in toy breed dogs like Chihuahuas. Hypoglycemia is low blood sugar. The pancreas makes the hormone insulin, when there is too much insulin the body can develop hypoglycemia. Chihuahuas can develop hypoglycemia even when they are healthy because ttheir low muscle mass can make it difficult for the body to store the glucose and keep its blood sugar properly regulated.

Because Chihuahuas are so small, they can be prone to hypoglycemia specifically when they are very young, usually seen in Chihuahua puppies that are 5 to 16 weeks of age. Hypoglycemia is generally caused by low body temperature, poor nutrition, sudden change in feed, water or schedule patterns, stress, illness, lack of food, or by using up stored energy without it being replenished. It is important to make sure that young puppies and very tiny Chihuahuas eat regularly throughout the day. Another preventative for hypoglycemia is daily dose of a high calorie supplement like Nutri-Cal.