Anal gland (anal sac) disease is one of the most common conditions seen in veterinary practice. The anal sacs are small scent glands located on either side of the anus that produce a pungent secretion used for scent marking. When they fail to empty normally, impaction, infection, and abscessation cause significant pain and welfare compromise.
Normal Function and Anatomy
Anal sacs sit at approximately 4 and 8 o'clock positions relative to the anus. They open via ducts just inside the anal margin. Secretion is normally expressed during defecation through pressure as firm stool passes. Small-breed dogs, obese dogs, and dogs with soft stools or food sensitivities have higher rates of anal gland problems.
Clinical Signs
- Scooting — dragging hindquarters along the floor — the most characteristic sign of anal gland discomfort
- Licking or biting at the base of the tail
- Difficulty or pain when sitting
- Swelling and redness beside the anus (abscess)
- Foul-smelling discharge from ruptured abscess
Conditions and Welfare Impact
Impaction: Anal sac secretion becomes thick and pasty, blocking normal expression. Mildly uncomfortable — manual expression by veterinarian or trained nurse relieves impaction.
Sacculitis (infection): Bacterial infection of impacted sacs causes intense pain, swelling, and fever. Requires antibiotic treatment (sometimes via infusion into the sac) and anti-inflammatories.
Abscessation: Untreated infection progresses to abscess formation with visible swelling, which may rupture spontaneously. Severe pain, tissue destruction, and welfare emergency. Requires surgical drainage, flushing, and systemic antibiotics. Healing may take weeks.
Treatment and Management
Manual expression of anal glands should be performed only when clinically indicated — routine expression in dogs without clinical signs may cause inflammation. Dogs with recurrent impaction benefit from:
- High-fibre diets — increasing stool bulk promotes natural expression
- Weight management in obese dogs
- Identifying and managing concurrent allergic or GI disease driving soft stools
- Surgical anal sacculectomy (removal of both glands) for dogs with chronic recurrence — eliminates the problem permanently at the cost of a surgical procedure
Welfare Significance
Anal gland disease causes chronic discomfort in affected dogs that owners may not recognise as pain — "scooting" is often treated as amusing rather than as a welfare signal requiring investigation. Early recognition and appropriate treatment prevents progression from impaction to abscess, avoiding significant suffering. Dogs with recurrent disease benefit from proactive rather than reactive management.