Feline Refeeding Syndrome Study Guide

Overview and Clinical Importance

Refeeding syndrome (RS) is a potentially fatal constellation of metabolic and electrolyte disturbances that occurs when nutrition is reintroduced to a severely malnourished or starved patient. The hallmark feature is severe hypophosphatemia, though hypokalemia, hypomagnesemia, thiamine deficiency, and altered glucose homeostasis are also characteristic. Cats are particularly susceptible to RS due to their unique metabolic requirements as obligate carnivores, including high dietary protein and thiamine needs, and their low hepatic glucokinase activity which predisposes them to hyperglycemia and subsequent insulin release during refeeding.

RS typically develops 2-5 days after nutrition is reinstated, though signs can appear within hours or be delayed up to 10 days. The condition is most commonly encountered in cats with hepatic lipidosis, prolonged starvation (greater than 3 weeks missing), severe weight loss, or concurrent diseases causing prolonged anorexia. Without aggressive monitoring and management, RS can result in hemolytic anemia, cardiac failure, respiratory failure, neurological dysfunction, and death.

Pathophysiology

Metabolic Adaptations During Starvation

During starvation, the body undergoes reductive adaptation to conserve energy and maintain vital functions. Key metabolic changes include decreased insulin secretion and increased glucagon levels, stimulating glycogenolysis. Once glycogen stores are depleted (typically within 6-72 hours), the body shifts to gluconeogenesis using amino acids from muscle protein and glycerol from lipolysis. Fat becomes the primary energy source through beta-oxidation and ketone body production.