Weight loss occurs when more calories are expended than are consumed. Healthy animals can experience weight loss, but in a
geriatric cat, a subtle decrease in weight can also be the first indication of illness. For example, cats with small intestinal
disease may lose weight before exhibiting anorexia, vomiting, or diarrhea. Unfortunately, weight changes in older cats are
often attributed merely to aging, so clients may not seek veterinary care or veterinarians may inadvertently delay a diagnostic
workup until marked weight loss is evident or additional clinical signs arise. Starting with a detailed history, work your
way through a complete workup in these patients.
ASK ALL THE RIGHT QUESTIONS
To start narrowing the differential diagnoses (see sidebar titled "Differential diagnoses for weight loss"), collect a complete history. Use open-ended questions to explore the owner's knowledge of the cat's diet, eating habits,
and energy level: What changes have occurred regarding activity? What diet is being fed? How much, where, and how often is
the cat being fed? What treats and supplements are given? How has the diet changed? How is the cat's appetite?
Differential diagnoses for weight loss
The answers to these questions may reveal important clues about the cat's weight loss. For example, in some households, pets
compete for food, and underfeeding results. Clients may feed a weight-loss diet and continue it even after an optimal weight
has been achieved. An arthritic or visually impaired cat may not be able to make it to food bowls that are difficult to access,
such as on a countertop or in a dark basement. And an inability to smell food, the administration of certain medications,
or a systemic illness can result in a decreased appetite, even in cats being fed a high-quality, palatable food.
Keep in mind that a good appetite does not rule out disease, because cats with certain conditions (e.g. hyperthyroidism, diabetes mellitus, malnutrition from malabsorption or maldigestion, internal parasites, exocrine pancreatic
insufficiency, nonsuppurative cholangitis-cholangiohepatitis complex) may have a normal or increased appetite. And if an owner
reports that the cat is interested in food but is unable or reluctant to eat, consider dental disease, oral or pharyngeal
masses or foreign bodies, chronic gingivitis-stomatitis,1 or retrobulbar masses or abscesses.
Detecting weight loss
Remember to ask about travel history; feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) testing, exposure,
and vaccination history; environmental exposures (e.g. second-hand smoke, herbicides); prior anesthesia; and any medications being given. Many medications can cause gastrointestinal
(GI) distress. Common examples are nonsteroidal anti-inflammatory drugs, glucocorticoids, chemotherapeutics, fluoroquinolones,
amoxicillin, ACE inhibitors (e.g. benazepril, enalapril), and digoxin. Medications (notably doxycycline), improper medication administration, and reflux into
the esophagus during anesthesia may cause esophageal stricture.
Next, ask the owner about specific body systems and other clinical signs. Cats with abdominal pain may lie in an unusual position
or object to being held in a way that puts pressure on the abdomen. Vomiting and diarrhea may help localize the problem to
the GI tract, although these are nonspecific signs of many conditions.
Checklist for Diagnosing the Cause of Weight Loss in a Geriatric Cat