This is a very controllable condition in dogs that occurs when the thyroid gland does not work efficiently. It can occur in any breed, and tends to happen as the dog reaches its senior years. However, it is quite a common condition in the Malamute, and can occur at a young age. There are many Malamutes that are suffering with hypothyroidism at about a year old. For this reason, many vets are not recognizing the condition in younger Malamutes.
I have included a comprehensive link to a document that explains hypothyroidism and its signs and symptoms. If your dog is suffering from one or two of the symptoms then ask your vet for the blood test.