Which endocrine disorders are noted as extra-GI causes of chronic diarrhea?

• A. Diabetes mellitus
• B. Addison's disease (dogs) and hyperthyroidism (cats)
• C. Hypothyroidism
• D. Cushing's disease

Answer: (B)

Endocrine disorders can affect gut function from outside the digestive tract, leading to chronic diarrhea through changes in motility, absorption, and fluid balance. In dogs, Addison's disease (hypoadrenocorticism) often causes persistent watery diarrhea due to electrolyte disturbances (low sodium, high potassium) and dehydration that impair intestinal function and mucosal perfusion. In cats, hyperthyroidism increases metabolic rate and gut motility, which can lead to diarrhea from accelerated transit and malabsorption. Other endocrine disorders like hypothyroidism typically slow the gut and cause constipation rather than diarrhea, while Cushing’s disease and diabetes mellitus are less classic causes of chronic diarrhea.