Feline Polyphagia Study Guide

Overview and Clinical Importance

Polyphagia (increased appetite) is a clinical sign that can indicate serious underlying disease in cats. Unlike dogs, cats are typically fastidious eaters, making any significant increase in appetite clinically important. The differential diagnosis varies significantly based on whether polyphagia occurs with weight loss (suggesting malabsorption, hypermetabolic states, or maldigestion) or weight gain (suggesting acromegaly or drug-induced causes). This topic is commonly tested on the NAVLE due to its diagnostic complexity and the importance of distinguishing between similar-presenting conditions.

Diagnostic Approach to Feline Polyphagia

The first step in evaluating polyphagia is determining whether the cat is losing or gaining weight. This single clinical finding dramatically narrows the differential diagnosis.

Differential Diagnosis by Weight Change

Hyperthyroidism

Hyperthyroidism is the most common endocrine disease in cats, affecting up to 1 in 300 cats. The median age at diagnosis is 13 years. More than 98% of cases are due to benign thyroid adenoma or adenomatous hyperplasia; thyroid carcinoma accounts for less than 2% of cases.