Feline Anal Sac Disease Study Guide

Overview and Clinical Importance

Anal sac disease encompasses a spectrum of conditions affecting the paired cutaneous diverticula located at the 4 o'clock and 8 o'clock positions lateral to the anus. While anal sac disease is significantly less common in cats compared to dogs (incidence of only 0.4% in cats versus 15.7% in dogs), it remains an important differential for any feline patient presenting with perianal discomfort, scooting, or excessive grooming of the hindquarters.

The anal sacs are lined by both sebaceous and apocrine glands in cats (unlike dogs which have only apocrine glands), and they secrete a foul-smelling, oily fluid that serves as a territorial marker and communication tool. Understanding the anatomy, pathophysiology, and treatment of feline anal sac disease is essential for the NAVLE, particularly in differentiating benign impaction from malignant neoplasia.

Anatomy and Physiology

Anatomical Location and Structure

The anal sacs are paired, balloon-like structures approximately pea-sized (5 mm diameter) when normal, located between the internal and external anal sphincter muscles. Each sac connects to the anal canal via a narrow duct that opens at the anocutaneous junction at approximately 120 degrees (4 o'clock) and 240 degrees (8 o'clock) lateral to the mucocutaneous junction.