A fishy smell coming from your dog almost always traces back to one of a few specific sources: anal glands, dental disease, a skin infection, or a reproductive/urinary issue. The fix depends entirely on where the smell is coming from, so the first step is figuring out the source. Most commonly, the culprit is your dog’s anal glands, two small sacs on either side of the anus that produce a distinctly foul, fish-like fluid used for scent marking.
Anal Glands: The Most Common Cause
Dogs have two small glands just inside the anus, each connected to a tiny duct that releases fluid during bowel movements. This secretion is how dogs leave scent information behind and why they sniff each other’s rear ends when they meet. Normally, the pressure of a firm stool passing through naturally squeezes the glands and empties them. You’d barely notice the smell.
Problems start when that natural emptying process fails. If your dog’s stool is soft or inconsistent, the glands don’t get enough pressure to express on their own. Over time, the fluid inside thickens and builds up, making expression even harder. The result is a persistent fishy odor, and you might also notice your dog scooting across the floor, licking their rear end excessively, or showing discomfort when sitting. In some cases, impacted glands can become infected or even rupture, causing visible swelling or drainage near the anus.
How to Fix an Anal Gland Problem
If the smell just started or seems intense, your dog likely needs a manual gland expression. A veterinarian or experienced groomer can do this in a few minutes. Some dogs only need it once, while others with chronic issues may need it every few weeks or months. If the glands are infected or abscessed, your vet will need to treat the infection directly.
The longer-term fix is getting your dog’s stool firmer and more consistent so the glands empty naturally. Adding fiber to your dog’s diet is the most effective approach. Pumpkin puree (plain, not pie filling) is a popular option. Commercial fiber supplements designed for dogs typically contain oat bran and psyllium. When introducing fiber, start with about a quarter of the recommended amount and increase gradually over a week to avoid digestive upset. Dietary changes alone can sometimes eliminate the need for manual expression entirely, or at least reduce how frequently it’s needed.
If your dog is on a low-quality food that produces soft stools, switching to a higher-quality diet with adequate fiber can make a significant difference. Look for foods that produce firm, well-formed stools rather than soft or loose ones.
Fishy Breath Points to Dental Disease
If the fishy smell is coming from your dog’s mouth rather than their backside, dental disease is the likely cause. Periodontal disease produces a rotten or fishy odor as bacteria accumulate on the teeth and below the gum line. Other signs include red or swollen gums, yellow or brown buildup on the teeth, and excessive drooling.
You can slow plaque buildup at home with dental chews, water additives, and regular tooth brushing using a dog-safe toothpaste. But once periodontal disease has set in, a professional dental cleaning under anesthesia is typically the only way to address it fully. Left untreated, the bacteria can spread to other organs, so a persistent fishy mouth odor is worth getting checked.
Skin and Ear Infections
Yeast overgrowth on your dog’s skin can produce a strong, musty, fishy odor. Yeast naturally lives on healthy dog skin, in ear canals, between toes, and in skin folds. When conditions shift (allergies, moisture, immune problems), yeast multiplies and causes infection. The skin becomes itchy, crusty, and may thicken over time to a rough, elephant-like texture. The smell can be intense, especially from ears, paws, and any deep skin folds.
Bathing with a medicated antifungal shampoo can help manage mild yeast infections. For ears, a veterinary ear cleaner used regularly can keep yeast in check. But recurring yeast infections usually signal an underlying issue like allergies or hormonal imbalance that needs to be addressed, or the infections will keep coming back.
Urinary and Reproductive Issues in Female Dogs
In female dogs specifically, a fishy odor from the genital area can signal a urinary tract infection, vaginitis, or a uterine infection called pyometra. UTIs cause fishy-smelling urine due to bacterial overgrowth in the bladder or kidneys. Watch for excessive water drinking, frequent urination, accidents in the house, straining to urinate, or changes in urine color. Severe kidney infections can cause lethargy, vomiting, decreased appetite, or fever.
Vaginitis, an inflammation of the vagina caused by bacteria or yeast, also produces a fishy smell. It can affect dogs of any age, including puppies, and is more common in breeds with certain structural features like English Bulldogs, which are prone to a hooded vulva that traps moisture and bacteria. Both vaginitis and pyometra require veterinary treatment. Pyometra in particular is a medical emergency in unspayed females.
Immediate Odor Removal at Home
While you work on the underlying cause, you can reduce the smell on your dog’s coat and bedding with a few practical steps. If your dog has expressed their anal glands on furniture or their fur, the oily secretion clings stubbornly to surfaces. A bath with a deodorizing dog shampoo will help on the coat. For fabrics, an enzymatic cleaner (the same type used for pet urine) breaks down the organic compounds in the secretion rather than just masking them.
Wipe your dog’s rear with unscented pet wipes after bowel movements if they tend to retain residue. For dogs with skin fold odor, keeping folds clean and dry with daily wipe-downs prevents yeast and bacteria from thriving. Wash your dog’s bedding in hot water weekly if odor is an ongoing issue.
When the Smell Signals Something Serious
Rarely, a persistent fishy smell from the anal area can be associated with anal sac tumors. These are sometimes detected during a routine rectal exam before any obvious symptoms appear. Warning signs include visible swelling near the anus, straining to defecate, constipation, lethargy, decreased appetite, increased thirst and urination, or weakness and swelling in the hind legs. If your dog has a fishy smell that doesn’t resolve with gland expression and dietary changes, or if you notice any of these additional symptoms, a veterinary exam can rule out more serious causes.