The anal sacs are glands located near the anus (rectum) that produce secretions that are normally expressed during defecation. The secretions from these glands are normally pungent (in fact, very smelly) and straw-colored with brown flecks. Anal sac contents may also be expressed in times of fright (producing a terrible odor in the area).
Dogs are more commonly affected with anal sac disease than cats, and small breed dogs are more commonly affected with anal sac impaction than large breed dogs. Older female dogs are more commonly affected with anal sac tumors.Types of anal sac disease include: Impaction, which can lead to inflammation or infection of the anal sacs
Infection or abscess formation
Tumors of the sac or related glandular tissues
What to Watch For
Scooting or dragging the anus on the ground or carpet
Frequent licking of the anus or tail base
Reluctance to sit or sitting asymmetrically to avoid pressure on the painful anal sac
Straining to defecate, difficulty defecating, production of ribbon-like stools
Painful swelling at the 4 o'clock or 8 o'clock locations around the anus
Similar signs can be seen in dogs with a different disease called perianal fistula, a severe condition that causes draining tracts around the anus. The breeds that most commonly develop perianal fistulae are German shepherd dogs and Irish setters.