Anal Glands in Dogs: Blockage, Inflammation, and When to Express Them
Anal Glands in Dogs: Blockage, Inflammation, and When to Express Them
What are anal sacs in dogs?
Anal sacs (anal glands, paranal sinuses) are two small paired glandular sacs in dogs, located at the 4 o'clock and 8 o'clock positions on either side of the anus. They produce a uniquely scented, oily secretion that serves for marking territory and social communication. Normally, anal sacs empty spontaneously during defecation due to the pressure of the fecal bolus on the glands.
Problems arise when the glands can no longer empty on their own—due to secretions that are too watery, stools that are too soft, or anatomical abnormalities. Blocked anal sacs become painful and can become inflamed or form abscesses.
Background + Scientific Context
Fossum (2019, *Small Animal Surgery*) describes the anatomy and surgical relevance of the anal sacs: Each anal sac has an opening (paranal duct) that opens directly next to the anus. The wall consists of glandular epithelium (apocrine and sebaceous glands). The secretion is viscous to pasty, brownish to grayish-yellow. Blockage occurs when the secretion thickens or the duct is mechanically obstructed—resulting in pressure buildup, pain, and inflammation. Abscessed anal sacs can perforate outward—a surgical emergency. Treatment: Flushing and expression under anesthesia; in cases of recurrence, anal sac excision (surgical removal).
Ettinger et al. (2017, *Textbook of Veterinary Internal Medicine*) describe the clinical signs of anal sac disease and differential diagnoses: A classic sign is scooting—the dog drags its hindquarters along the ground in an attempt to relieve pressure and itching through friction. Other signs: intense licking of the perineum, chewing at the base of the tail, sitting down with a groan, perianal odor (fishy and musty). Differential diagnoses: Worm infestation (tapeworms can cause similar symptoms), anal dermatitis, rectal polyps. Diagnosis: Manual palpation of the anal sacs, visual examination of the perineum.
Harvey (1992, *Veterinary Clinics of North America*, https://pubmed.ncbi.nlm.nih.gov/1598748/) describes the epidemiology, risk factors, and prevention: Anal sac disease is more common in small breeds (Dachshunds, Toy Poodles, Chihuahuas, Beagles) due to anatomical narrowing of the excretory ducts. Overweight dogs are at increased risk due to reduced fecal pressure. A lack of fiber in the diet leads to soft stools, which do not exert sufficient pressure on the anal sacs. Increasing crude fiber in the diet and normalizing weight can reduce recurrences in predisposed dogs. Routine prophylactic expression is not indicated in asymptomatic dogs—it can stimulate secretion and cause mucosal irritation.
Vitomalia-Position
Anal glands aren't just "a minor nuisance"—they're a problem that needs to be treated. If you notice your dog scooting, don't try home remedies; instead, have a veterinarian check the anal glands. Preventively expressing healthy anal glands is counterproductive.
When does the topic of anal sacs become relevant?
- Scooting (dragging the bottom): an early sign of constipation or inflammation
- Excessive licking of the perineum or biting at the base of the tail
- A fishy, musty odor around the anus
- Visible swelling near the anus: possible abscess — see a veterinarian immediately
- Dogs with recurrent episodes: Assessment of weight and fiber content in the diet
Practical application
Clinical signs of anal sac disease by severity:
| Severity | Clinical signs | Action |
|---|---|---|
| Constipation | Scooting, perianal odor, light licking | Veterinary Milking |
| Inflammation | Swelling, tenderness, excessive licking | Veterinarian, rinse + antibiotics |
| Abscess | Redness, risk of perforation, severe swelling | Emergency Veterinarian |
| Exstirpation | Recurrence of the disease despite treatment | Surgical removal |
Prevention of recurrent anal sac problems: - Check the dietary fiber content: ensure there is enough fiber for firm stools - Weight management for overweight dogs - Have your pet checked regularly by a veterinarian; do not express the glands yourself (unless instructed to do so) - For small breeds at high risk: veterinary palpation every six months
Common Mistakes & Myths
- "Scratching the floor always means worms." There are several causes of scooting—anal sac issues are more common than worm infestations. Both need to be evaluated by a veterinarian. Even administering deworming medication without a diagnosis is not a solution.
- “Regularly expressing the anal glands helps prevent problems.” Prophylactic expression is not recommended for dogs without symptoms and can stimulate secretion production and irritate the mucous membrane. Express the glands only if clinical signs are present or as directed by a veterinarian.
- “I can express the anal sacs myself.” External expression (pressing from the outside) only partially empties them. Internal expression (inserting a finger into the rectum) is more effective, requires practice, and should be performed by a veterinarian or after receiving proper instruction. Improper expression can cause damage to the mucous membranes.
Current State of Research (2026)
Anal sac disease is well-defined in veterinary medicine. Surgical excision is the standard treatment for recurrent cases and offers a good prognosis. The link between diet (fiber deficiency, obesity) and anal sac impaction is clinically recognized. Antibiotic resistance in bacterial anal sac abscesses (especially Pseudomonas) increasingly requires an antibiogram prior to treatment.
Frequently Asked Questions
Why does my dog drag his butt across the floor?
The most common cause is overfilled or inflamed anal glands—not (as is often assumed) worms. Other causes include anal itching due to parasitic infestation and anal dermatitis. A veterinary examination is necessary to palpate the anal glands and rule out parasites.
How often should anal glands be expressed?
Only if clinical signs are present (scooting, odor, swelling) or as directed by a veterinarian. For dogs without any issues, regular expression is not necessary—it is actually counterproductive. In cases of recurrence, the problem often lies in diet or weight.
Can I express my dog's anal glands myself?
External expression is possible, but it only partially empties the sac. For thorough emptying, the internal method (performed by a veterinarian) is more effective. Do not attempt to express the sac yourself unless instructed to do so by a veterinarian—improper expression can cause injury.
Related terms
Sources & Further Reading
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Fossum, T. W. (2019). Small Animal Surgery (5th ed.). Mosby. ISBN 9780323443449.
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Ettinger, S. J., Feldman, E. C., & Côté, E. (Eds.) (2017). Textbook of Veterinary Internal Medicine (8th ed.). Saunders. ISBN 9780323312110.
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Harvey, C. E. (1992). Anal sac disease. Veterinary Clinics of North America: Small Animal Practice, 22(3), 621–634. https://pubmed.ncbi.nlm.nih.gov/1598748/