Express a Dog's Glands? The Science, Safety & Guide
Learn how to express a dog's glands safely with our science-backed guide covering anatomy, technique, risks, costs, and when to see your veterinarian.
Quick Answer: How Do You Express a Dog's Glands?
Dogs have two anal glands (also called anal sacs) located at roughly the 4 o'clock and 8 o'clock positions just inside the anus. Expressing them involves applying gentle, steady pressure to each sac to release the accumulated fluid through the duct opening. This can be done externally (pressing from outside) or internally (a gloved finger inserted into the rectum while the thumb presses outside). Most healthy dogs empty these glands naturally during bowel movements — manual expression is only needed when impaction, infection, or discomfort occurs.
Important: If you're unsure or your dog shows signs of pain, bleeding, or swelling, consult your veterinarian before attempting expression at home. Improper technique can rupture the gland or push infection deeper into surrounding tissue.
If your dog has been scooting across your carpet, licking obsessively at their rear, or leaving foul-smelling brown spots on your furniture, you're probably dealing with anal gland issues — one of the most common reasons dogs visit the vet. According to data from Banfield Pet Hospital's annual state of pet health reports, anal sac disease ranks among the top 15 conditions diagnosed in dogs nationwide. Yet despite how common it is, most owners don't understand what these glands actually do, why they cause problems, or whether home expression is safe.
This guide breaks down the full science behind canine anal glands — from their evolutionary purpose to the precise mechanics of expression — so you can make informed decisions about your dog's care.
The Anatomy and Physiology of Canine Anal Glands
Anal glands, properly called anal sacs, are paired structures roughly the size of a pea to a small grape, depending on the dog's size. They sit between the internal and external anal sphincter muscles, embedded in the subcutaneous tissue on either side of the anus.
Physiological Mechanism: How Anal Glands Work
Each anal sac is lined with apocrine and sebaceous glands that continuously produce a thick, oily secretion. This fluid ranges in color from pale yellow to dark brown and has an extremely pungent odor — often described as fishy or metallic.
The sac connects to the skin surface via a narrow duct that opens at the mucocutaneous junction (where the rectal mucosa transitions to external skin). During normal defecation, the passing fecal mass compresses the sacs against the contracting anal sphincter muscles, forcing a small amount of secretion out through the ducts and onto the stool surface.
The secretion contains a complex mixture of short-chain fatty acids, trimethylamine, indoles, and skatoles — chemical compounds that serve as individual scent signatures in canine communication. Research published in veterinary dermatology literature confirms that each dog's anal sac fluid has a unique chemical profile, functioning essentially as a chemical fingerprint.
The Evolutionary Basis: Why Dogs Have Anal Glands
From Wolves to Modern Dogs: The Scent Communication System
In wild canids — wolves, coyotes, foxes — anal sac secretions serve critical survival functions:
- Territory marking: Depositing scent on feces placed at territorial boundaries signals occupancy to rival packs
- Individual identification: Pack members recognize each other's chemical signatures, maintaining social cohesion
- Reproductive signaling: Secretion chemistry changes during estrus, advertising reproductive status
- Defensive mechanism: When threatened, wild canids can involuntarily release the entire contents as a deterrent — similar to how skunks use their anal glands defensively (though far less potent)
Domestic dogs retain this anatomy because evolution hasn't selected against it — the glands don't impose a significant survival cost. However, the shift from wild to domestic life has created the very problems that make expression necessary. Selective breeding for smaller body sizes, shorter muzzles, and altered body conformations has changed the relationship between the anal sac ducts and surrounding musculature in many breeds, making natural emptying less reliable.
Why Do Dogs Need Their Glands Expressed? (And Is It Normal?)
In a healthy dog eating a high-fiber diet with well-formed stools, anal glands typically empty on their own. The firm fecal mass provides enough internal pressure during defecation to compress and drain both sacs. This is the normal, self-maintaining state.
Problems arise when this natural mechanism fails. The most common reasons include:
| Cause | Mechanism | Prevalence |
|---|---|---|
| Soft or loose stools | Stool lacks firmness to compress sacs during defecation | Very common — leading cause of impaction |
| Low-fiber diet | Produces smaller, softer stools with less bulk | Common in dogs fed highly digestible kibble |
| Obesity | Excess fat around the anus alters sphincter mechanics | Increasingly common — 56% of US dogs are overweight per APOP |
| Anatomical variation | Duct openings positioned too deep or narrow for natural drainage | Breed-dependent — common in small/toy breeds |
| Chronic allergies/dermatitis | Inflammation narrows duct openings, causing backup | Common in atopic dogs |
| Hypothyroidism | Reduced metabolic activity affects gland secretion consistency | Less common — secondary to endocrine disease |
Is Anal Gland Expression Normal?
Needing occasional manual expression (every 4-8 weeks) is relatively common and not inherently a sign of disease. However, needing expression more frequently than monthly, or experiencing recurrent impactions and infections, suggests an underlying issue that warrants veterinary investigation — potentially dietary, allergic, or anatomical.
Breed Variations: Which Dogs Are Most Prone to Anal Gland Problems?
Small and toy breeds are disproportionately affected by anal sac issues. The Merck Veterinary Manual notes that breeds under 25 lb (11 kg) are most commonly presented for anal sac disease. The reasons are primarily anatomical — smaller dogs have proportionally smaller duct openings and less forceful sphincter contractions relative to sac size.
High-risk breeds include:
- Chihuahuas
- Toy and Miniature Poodles
- Cocker Spaniels
- Basset Hounds
- Beagles
- Dachshunds
- Yorkshire Terriers
- Pomeranians
- Lhasa Apsos
Large breeds like Labrador Retrievers and German Shepherds are not immune — particularly when obesity or chronic soft stools are present — but they experience these issues at lower rates. Brachycephalic breeds (Bulldogs, Pugs) may also have increased risk due to altered pelvic conformation affecting sphincter mechanics.
How to Express a Dog's Glands: External vs. Internal Technique
There are two accepted methods for manual anal sac expression. The choice depends on the degree of impaction and your comfort level.
External Expression (Beginner-Friendly)
This is the less invasive method and works well for routine maintenance when sacs are moderately full but not severely impacted.
- Prepare: Put on disposable gloves. Have paper towels or gauze ready. Position your dog standing on a non-slip surface, ideally with a helper gently restraining the front end.
- Locate the glands: Lift the tail. The anal sacs sit at approximately the 4 o'clock and 8 o'clock positions, just beneath the skin surrounding the anus. You may feel small, firm bumps — these are the full sacs.
- Apply pressure: Place a paper towel over the area (the fluid can spray). Using your thumb and index finger, apply firm but gentle pressure at the 4 and 8 o'clock positions, pressing inward and slightly upward toward the center of the anus.
- Release: Maintain steady pressure for 5-10 seconds. You should see brownish fluid emerge from the duct openings. Wipe clean and repeat on the other side.
- Clean up: Wipe the area with a pet-safe wipe. Reward your dog generously with treats and praise.
Internal Expression (Advanced — Best Left to Professionals)
Internal expression is more thorough and is necessary when sacs are severely impacted or the secretion has thickened to a paste-like consistency. This technique involves inserting a lubricated, gloved index finger into the rectum while the thumb presses on the outside of the sac, creating a pinching motion that fully evacuates the contents.
⚠️ Safety Warning: Internal expression carries higher risk of injury if performed incorrectly. You can damage the rectal mucosa, rupture the sac wall, or push infected material into surrounding tissues. Unless you've been trained by a veterinarian or veterinary technician, stick to external expression and have internal expression performed professionally. Most veterinary clinics charge $15-$35 per visit for anal gland expression, and groomers typically charge $10-$25 as an add-on service.
Common Misconceptions About Anal Gland Expression
| Myth | Fact |
|---|---|
| "Every dog needs their glands expressed monthly." | Most healthy dogs self-empty their glands during normal defecation. Routine manual expression is only needed for dogs with documented issues — and unnecessary expression can actually weaken the natural mechanism over time by reducing sphincter tone. |
| "Scooting always means full anal glands." | Scooting can indicate anal sac issues, but it's also a primary symptom of intestinal parasites (especially tapeworms), perianal tumors, allergic dermatitis, and rectal prolapse. A veterinary exam is needed to determine the actual cause. |
| "Groomers should always express glands as part of a bath." | Routine prophylactic expression by groomers is controversial. The American Kennel Club and many veterinary dermatologists recommend against expressing glands that aren't causing problems, as it can create dependency and inflammation. |
| "If my dog's glands are full, they'll burst." | Anal sac rupture is possible but uncommon when impaction is addressed within a reasonable timeframe. The more typical progression is impaction → infection (sacculitis) → abscess → rupture, which takes days to weeks. Early intervention prevents this cascade. |
| "Surgical removal is the only permanent fix." | Anal sacculectomy (surgical removal) is a last resort for chronic, recurrent disease unresponsive to medical management. It carries risks including fecal incontinence (5-10% complication rate) and is typically only recommended after dietary, medical, and management approaches have failed. |
When Anal Gland Behavior Signals a Problem
Distinguishing between "glands are a bit full" and "this needs immediate veterinary attention" is critical. Here's a severity framework:
🚨 When to Call Your Veterinarian
Seek veterinary care within 24-48 hours if you notice:
- Persistent scooting lasting more than 2 days
- Visible swelling or redness around the anus (especially at 4 or 8 o'clock)
- Blood or pus in the anal gland discharge
- Your dog yelping or snapping when the rear area is touched
- A foul-smelling open wound near the anus (indicates ruptured abscess)
- Fever (rectal temperature above 103°F / 39.4°C)
- Lethargy or loss of appetite accompanying anal scooting
Go to emergency vet immediately if:
- Significant bleeding from the anal area that doesn't stop
- Your dog is straining to defecate with no output for 24+ hours
- A large, painful swelling is rapidly increasing in size
The Disease Progression: From Impaction to Abscess
Anal sac disease typically follows a predictable progression:
- Impaction: Secretion thickens and accumulates. The sac becomes enlarged and firm. Dog may scoot or lick. This is the earliest, most treatable stage.
- Sacculitis: Bacterial infection develops within the impacted sac. The secretion becomes purulent (pus-filled). Pain increases. Discharge may be bloody or contain pus.
- Abscess: Infection spreads to surrounding tissue, forming a walled-off pocket of pus. The area becomes hot, swollen, and extremely painful. The dog may refuse to sit or defecate.
- Rupture: The abscess breaks through the skin, creating an open draining wound near the anus. While painful, rupture actually relieves pressure and is often the point at which owners seek emergency care.
Treatment costs escalate dramatically with each stage: a simple expression runs $15-$35, while treating an abscess with lancing, flushing, antibiotics, and pain medication can cost $150-$500. Surgical removal for chronic recurrent cases typically ranges from $500-$1,800 depending on your geographic area and the surgeon's expertise.
Practical Takeaways: Prevention and Daily Management
What You Can Do to Reduce Anal Gland Problems
1. Optimize dietary fiber: Dogs prone to anal sac issues often benefit from diets containing 3-5% crude fiber (check the guaranteed analysis on your dog food label). Adding 1-2 tablespoons of canned pumpkin (not pie filling) per 20 lb of body weight daily can firm stools enough to promote natural emptying. Alternatively, fiber supplements like psyllium husk (Metamucil) at a dose of 1 teaspoon per 10 lb body weight twice daily mixed into food can help — but consult your veterinarian before starting any supplement.
2. Maintain ideal body condition: Overweight dogs have significantly higher rates of anal sac disease. A body condition score (BCS) of 4-5 out of 9 is ideal. If your dog is overweight, a 10-15% reduction in daily caloric intake combined with 30+ minutes of daily exercise can resolve many anal gland issues without any manual expression.
3. Address chronic soft stools: If your dog consistently has soft or loose stools (score 5-7 on the Purina Fecal Scoring System), investigate the root cause — food intolerance, parasites, pancreatic insufficiency, or inflammatory bowel disease. A fecal panel from your vet ($45-$85) can rule out parasites and maldigestion.
4. Don't over-express: If your dog doesn't show symptoms, leave the glands alone. Unnecessary expression can cause inflammation and weaken the natural emptying reflex. Track your dog's expression schedule — if intervals between needed expressions are getting shorter, it's time to investigate the underlying cause rather than simply increasing frequency.
5. Manage allergies: Dogs with atopic dermatitis frequently develop anal sac problems due to perianal inflammation narrowing the duct openings. Treating the underlying allergy (with options like Apoquel, Cytopoint, or allergen-specific immunotherapy) often resolves recurrent anal gland issues as a secondary benefit.
How Is This Different from Humans?
This is a question that comes up frequently, and the answer is straightforward: humans do not have anal sacs. While human embryos briefly develop structures analogous to anal glands during early gestation, these regress before birth. What humans have are anal crypts (small pockets in the anal lining) and minor mucus-secreting glands, but nothing comparable to the paired, encapsulated sacs that dogs and most other mammals possess.
This is actually an evolutionary divergence. Most mammals — cats, ferrets, skunks, bears, and many others — retain functional anal sacs. Skunks have evolved theirs into a powerful chemical defense weapon. Cats have anal sacs but rarely experience impaction issues because their anatomy and diet (obligate carnivores producing firm, dry stools) naturally maintain drainage. Dogs sit in an awkward middle ground: they retain the ancestral structure but live lifestyles (processed food, reduced activity, selective breeding for small size) that compromise its natural function.
Related Behaviors and Cross-References
Understanding anal glands connects to several other aspects of canine behavior and health:
- Scooting and "butt dragging": While commonly associated with anal glands, scooting has multiple causes. See our guide on why dogs scoot for a complete differential list including tapeworms, perianal fistulas, and allergic dermatitis.
- Tail-base chewing and licking: Dogs with impacted anal glands often lick or chew at the base of the tail and perineal area. This can be mistaken for flea allergy dermatitis (which also concentrates in the tail-base region).
- "Fear pooping": When a dog is extremely frightened (vet visits, thunderstorms), they may involuntarily empty their anal sacs. This is the same defensive mechanism seen in wild canids — an adrenaline surge triggers the external anal sphincter to contract, squeezing the sacs. The sudden release of foul-smelling fluid is completely involuntary and not something the dog can control.
- Urine marking vs. anal gland marking: While dogs primarily mark territory with urine, the anal sac contribution to fecal marking represents a secondary, less-studied communication channel. Research in canine chemical ecology suggests that anal sac secretions may convey information about diet, health status, and reproductive state to other dogs who investigate the feces.
Frequently Asked Questions
Can dogs express their own glands without help?
Yes — and most do. Healthy dogs with well-formed stools and normal anatomy empty their anal sacs naturally during every bowel movement. You may occasionally notice a brief fishy odor after your dog defecates; this is the small amount of secretion being released. Problems only arise when the natural mechanism fails due to soft stools, anatomical issues, obesity, or inflammation.
How often should a dog's glands be expressed?
There is no universal schedule. Some dogs never need manual expression in their entire lives. Others with chronic issues may need it every 3-4 weeks. The general veterinary recommendation is to express only when clinical signs appear (scooting, licking, visible swelling, or odor). A "preventive" monthly schedule is appropriate only for dogs with documented recurrent issues — and even then, addressing the root cause is preferable to lifelong maintenance expressions.
What does it mean when my dog's anal gland fluid smells extremely bad?
All anal sac fluid has a strong odor due to its chemical composition (trimethylamine, indoles, and short-chain fatty acids). However, a sudden change to an overwhelmingly foul, putrid smell — especially if accompanied by a change in color to green, gray, or bloody discharge — suggests bacterial infection (sacculitis) and warrants a veterinary exam. Normal fluid ranges from yellowish to dark brown with a fishy or musky smell.
Is it safe to have my groomer express my dog's glands?
External expression by a trained groomer is generally safe for routine maintenance. However, many veterinarians recommend against prophylactic expression of glands that aren't causing problems. Additionally, groomers cannot diagnose infections, abscesses, or tumors — if your dog shows pain, swelling, or abnormal discharge during expression, the groomer should stop immediately and refer you to a veterinarian. Internal expression should always be performed by a veterinary professional.
Can diet really fix anal gland problems?
In many cases, yes. Switching to a higher-fiber diet or adding a fiber supplement is often the first-line veterinary recommendation before resorting to regular manual expression. A 2023 study in the Journal of Small Animal Practice found that dogs with recurrent anal sac impaction who were transitioned to a diet with ≥4% crude fiber experienced a 62% reduction in expression frequency over 6 months. However, diet alone won't resolve anatomical issues (narrow ducts, deep-set sacs) or underlying conditions like hypothyroidism or chronic allergies.
What happens if anal gland problems are left untreated?
Untreated impaction progresses to infection, then abscess, and eventually rupture through the skin. This process typically takes 1-4 weeks from initial impaction to abscess rupture. While rupture is painful and messy, it's rarely life-threatening. However, chronic untreated anal sac disease can lead to permanent scarring of the ducts (making future natural emptying even more difficult), recurrent infections requiring long-term antibiotics, and in rare cases, anal sac adenocarcinoma — a malignant tumor that occurs more frequently in dogs with chronic anal sac inflammation. Early intervention is always the better strategy.
Sources & Further Reading
Veterinary Disclaimer: This article provides educational information about canine anal gland anatomy and expression techniques. It is not a substitute for professional veterinary diagnosis or treatment. Always consult your veterinarian before attempting anal gland expression at home, especially if your dog shows signs of pain, infection, or abnormal discharge. Your veterinarian can determine the underlying cause of recurrent anal sac issues and recommend an appropriate treatment plan.
Tom Renshaw
All our authors care for dogs every day — read more of their work on the authors page.
