Polyphagia (consumption of food in excess) can be a result of abnormalities in the areas of the brain that control hunger. This may be related to trauma, tumors, infections, or stress. Secondary causes may be drug induced (steroids, anticonvulsants, etc) or due to a variety of physiologic abnormalities induced by environmental change or disease.
The most common causes of polyphagia in the dog are hyperadrenocorticism (cushings), diabetes mellitus, parasitism, and pancreatic insufficiency. The most common causes of polyphagia in the cat include hyperthyroidism and diabetes mellitus. These disease syndromes are often accompanied by other clinical signs such as increased drinking and urination, weight loss, and vomiting/diarrhea. There are many other causes of polyphagia which are not discussed in this blog.
Regardless, increased appetite in a dog or cat can indicate serious disease and a physical examination and routine blood tests by your primary care veterinarian is the first step. If not taken care of in a timely fashion many of these diseases may results in a life-threatening situation.
-Dr. Robert Runde