Most Likely Causes (Ranked)
Anal glands (also called anal sacs) are two pea-to-grape-sized glands located at roughly 4 o'clock and 8 o'clock positions just inside your dog's anus. They produce a thin, brownish fluid with an intensely fishy or metallic smell that serves as a scent marker (it's why dogs sniff each other's rear ends). Normally, the pressure of firm stool empties these glands with each bowel movement. When stool is too soft, the glands don't get enough pressure to express, and the fluid accumulates. Small and medium breeds are more prone to this than large breeds.
When anal glands stay full for too long, the accumulated fluid can become thick, impacted, and infected. Bacteria enter through the duct and multiply in the warm, stagnant fluid. An infected anal gland produces an even worse smell than a normal one — stronger, more pungent, and sometimes with a yellowish or greenish discharge rather than the normal brown. If left untreated, an infected gland can abscess and rupture through the skin beside the anus.
In female dogs, a urinary tract infection can produce a strong fishy odor, especially around the vulva area. Bacterial infections in the urinary tract can change the smell of urine and cause discharge that carries a fishy scent. Older spayed females and dogs with recessed vulvas (a condition called vulvar fold dermatitis) are more susceptible.
Severe dental disease in dogs — especially advanced periodontal disease with infected gums — can produce a fishy or rotten smell from the mouth. This is technically a different source than you might expect when the dog "smells fishy," but because dogs lick themselves, the smell can end up on their fur and bedding, making it seem like a body odor issue.
Yeast infections on the skin (Malassezia dermatitis) produce a distinctive musty, sweet, or sometimes fishy odor. These are common in skin folds, ears, between toes, and on the belly. Bacterial skin infections can also produce fishy or sour odors. Dogs with allergies, chronic moisture in skin folds, or those that swim frequently are most susceptible.
How to Fix It
Get the Anal Glands Expressed
$20-50 (vet or groomer)This is the most common fix. Most groomers and all veterinary clinics offer this service.
- 1Book an appointment with your vet or groomer for anal gland expression. Many groomers include this as part of a bath package. Vet techs can do it during a routine visit — just ask.
- 2External expression (what groomers do) applies pressure from outside to squeeze the glands. Internal expression (what vets do with a gloved finger) is more thorough and recommended if the glands are frequently problematic.
- 3After expression, the smell should improve immediately. If the fluid is thick, dark, or gritty (rather than thin and brown), mention it to the vet — this can indicate early impaction.
- 4Most dogs need expression every 4-8 weeks if they don't self-express naturally. Some dogs never need it. If your dog needs it more often than every 3-4 weeks, discuss long-term options with your vet.
Add Fiber to Firm Up Stool
$5-15/monthFirmer stool puts more pressure on the anal glands during bowel movements, helping them empty naturally. This is the best long-term prevention.
- 1Add plain canned pumpkin (not pie filling) to your dog's food — 1-2 tablespoons per meal for medium dogs. Pumpkin is high in fiber and most dogs love the taste.
- 2Alternatively, add psyllium husk powder (Metamucil, unflavored) — 1/2 teaspoon per 10 lbs of body weight, mixed into wet food.
- 3Make sure your dog drinks enough water when increasing fiber — fiber without adequate water can cause constipation rather than firmer stool.
- 4Give it 1-2 weeks to see results. If your dog's stool becomes firm and well-formed, the anal glands may start self-expressing and the fishy smell will resolve on its own.
Treat Anal Gland Infection (Vet Required)
$100-400If the glands are infected or abscessed, this is not a DIY situation. Your vet needs to treat it.
- 1The vet will sedate or anesthetize your dog (if needed) and manually express and flush the infected gland.
- 2Antibiotics will be prescribed — typically oral antibiotics for 10-14 days and sometimes topical antibiotic ointment infused into the gland.
- 3Pain medication may be prescribed for the first few days, especially if an abscess was present.
- 4If abscesses are recurrent, your vet may discuss surgical removal of the anal glands (anal sacculectomy). This permanently solves the problem but carries a small risk of fecal incontinence (about 2-5%), so it's typically reserved for chronic, severe cases.
When to Call a Professional
You see blood or pus near your dog's anus — this indicates infection or a ruptured abscess. See a vet within 24 hours.
Your dog is scooting excessively and crying out — pain during scooting or defecation suggests impacted or infected glands that need professional attention.
There's visible swelling next to the anus — a swollen lump beside the anus is likely an anal gland abscess. Don't squeeze it — let the vet handle it.
The fishy smell is from the mouth and your dog has stopped eating — severe dental disease in dogs can cause oral pain that prevents eating. This needs veterinary dental care.
The smell is accompanied by frequent urination, straining, or blood in urine — especially in female dogs, this combination suggests a UTI or more serious urinary issue that needs vet attention.
How to Prevent It
Feed a high-fiber, high-quality diet — firm stool is the #1 natural anal gland maintenance tool. Look for dog foods with fiber content above 4% or supplement with canned pumpkin.
Keep your dog at a healthy weight — overweight dogs have more anal gland problems because fat deposits around the glands prevent proper expression during bowel movements.
Schedule regular expression if needed — if your dog doesn't self-express, every 4-8 weeks is typical. Many groomers include this in their services.
Annual dental cleanings — professional dental cleanings ($300-700 under anesthesia) prevent the dental disease in dogs that causes mouth-related fishy odors. Daily tooth brushing is ideal but even 3 times per week helps significantly.
Watch for early signs — scooting, excessive licking, and sitting uncomfortably are all early warning signs that the glands need attention. Addressing it early prevents infection.
What Are Anal Glands, Exactly?
Anal glands (anal sacs) are two small pouches located just inside your dog's rectum, at the 4 o'clock and 8 o'clock positions. Each gland has a tiny duct that opens onto the edge of the anus. The glands produce an oily, brownish fluid with a powerful fishy or metallic odor that's unique to each dog — essentially a scent fingerprint.
In the wild, this scent-marking system helps canines identify each other and mark territory. When a dog has a bowel movement, the firm stool presses against the glands and naturally squeezes out a small amount of fluid. This is why dogs are so interested in sniffing each other's feces and rear ends — they're reading scent information.
Domesticated dogs, especially small breeds, often have anal glands that don't empty efficiently. Soft commercial diets produce softer stool that doesn't provide enough pressure, and selective breeding has changed body proportions in ways that can affect gland positioning. This is why anal gland issues are so common — it's essentially a side effect of domestication.
Frequently Asked Questions
You can, but most people prefer to have a groomer or vet do it. External expression involves placing a cloth over the area and gently squeezing on either side of the anus at the 4 and 8 o'clock positions. The smell is intense and the fluid can spray, so do it in a tub or outside. If you try and nothing comes out, or if your dog is in pain, stop and see a vet — forceful expression can damage the glands. Many groomers charge only $10-20 for this service, making it worth the convenience.
If your dog is self-expressing naturally (no fishy smell, no scooting), the answer is never — don't express glands that don't need it, as unnecessary expression can cause inflammation. If your dog does need it, every 4-8 weeks is typical. Some dogs need it monthly, some quarterly. If you find yourself going more often than every 3 weeks, talk to your vet about dietary changes or other solutions.
Small breeds (Chihuahuas, Toy Poodles, Shih Tzus, Beagles, Cocker Spaniels) have disproportionately small duct openings relative to gland size, making natural expression more difficult. They also tend to produce softer stool on commercial diets. Obesity, which is common in small breeds, further compounds the issue by changing the anatomy around the glands. Larger breeds generally have fewer issues because their larger stool provides adequate pressure.
No. The anal gland fluid is just a scent secretion — it's unpleasant-smelling but not toxic or harmful to humans. It washes out of fabric with regular laundry. The smell on furniture can be cleaned with an enzymatic pet odor cleaner (like Nature's Miracle), which breaks down the proteins in the secretion rather than just masking the smell.