Appetite Changes

Introduction: Changes in appetite can involve either an increase or a decrease in appetite. Changes in food preference or in behavior while eating are also common.

Increase in Appetite:
Increased appetite (medical term: polyphagia) is usually noted by owners when the animal begins to beg for food more often or begins to acquire food from outside sources, like the garbage can. Sometimes a previously finicky pet will become ravenously hungry and devour its food with a vigor that may surprise the owner. Increased appetite may or may not indicate a medical problem; however, any noted or perceived increase in appetite should always be reported to the petís veterinarian. 

Drastic increases in appetite are usually fairly obvious and pose no challenge in detection. The subtle appetite increase, however, creates a more difficult situation to diagnose. The important element in discovering a subtle appetite increase is knowing how much a pet normally eats. This concept is given more attention in the nutrition discussion on page A575. Unfortunately, many pet owners have only a vague idea of how much food their pet eats daily. The problem is compounded when two or more pets eat together, often unobserved. Occasionally, when a pet is brought in for a checkup because of perceived weight loss or appetite increase, the owner finds that another pet in the household is the culprit, eating more than it should and depriving the first patient of its normal amount. Knowing how much a pet should be eating, making available that amount regularly, and observing that petís daily appetite are essential in maintaining a healthy pet.

Conditions which may lead to polyphagia include the following:

  1. Behavioral abnormalities
  2. Growth
  3. Pregnancy
  4. Diabetes
  5. Overdosage of insulin to a diabetic
  6. Hyperadrenocorticism (Cushingís disease)
  7. Pancreas malfunction
  8. Cancer (some types)

Decrease in Appetite:
Decreased appetite (medical term: hyporexia or anorexia) is one of the most common problems encountered by veterinarians. The list of possible causes is much longer for an animal with a decrease in appetite than it is for an increase in appetite; therefore, anorexia sometimes creates a diagnostic challenge.

The following are several reasons why it is important not to wait too long before consulting a veterinarian when an animalís food intake decreases:

First, an animal cannot properly communicate exactly what hurts, how long it has been going on, or what it may have eaten. Many animals are masters at hiding their discomfort until a problem has progressed to a possibly dangerous level. This is not always the case, but it is always best to see a professional sooner than later. "Waiting a couple of days to see" often compounds the problem.

Second, healing from any insult or injury to the body requires a great deal of energy. This energy is usually supplied to the tissues from ingested food.

With a few exceptions, episodes of illness are the worst possible times for anorexia to occur. Not eating compounds the problems the body must overcome. Waiting will delay the healing process in many of these cases simply due to the lack of good nutrition and energy.

Third, some diseases are zoonotic in nature, which means they may be contagious to the petís owners and other people. Waiting any time at all increases the risk of exposure and spreading of the disease to family members.

Some of the conditions which may lead to hyporexia/anorexia include the following:

  1. Olfactory disorders (inability to smell food)
  2. Unpalatable diet (food that is not eaten due to taste, texture etc.)
  3. Stress
  4. Behavioral problems (petís manipulation of owner to obtain treats/human food)
  5. Oral pain and diseases (including dental disease, oral infections, and others)
  6. Systemic illness (infection, degenerative disease, cancer, toxicity, trauma, or autoimmune disease)

Diagnosis: A thorough history and physical exam are often the first place to start. At this point, the doctor may recommend additional testing, or begin some type of treatment. Additional testing can include CBC, blood (serum) chemistry profile, and urine analysis; along with imaging studies such as radiographs, ultrasound, or endoscopy. For more information on the above tests, refer to Section D of this manual.

Treatment: The treatment of anorexia and polyphagia depends wholly on the underlying condition. The best strategy for solving these problems is to diagnose and treat the primary cause of a change in appetite. Some medications which stimulate appetite do exist; however, these are only used occasionally.