A fishy smell coming from your dog’s urine usually points to a urinary tract infection, anal gland issue, or vaginal infection in female dogs. The smell isn’t normal, and in most cases it signals bacteria producing odor compounds somewhere in or near the urinary tract. The good news is that the most common causes are treatable, often resolving within a week or two.
Urinary Tract Infections Are the Most Common Cause
Bacterial urinary tract infections are the number one reason dog urine takes on a strong, fishy, or foul odor. Bacteria multiply in the bladder and break down compounds in the urine, releasing sulfur-based chemicals that create that distinctive smell. You might also notice your dog urinating more frequently, straining to pee, or having accidents indoors.
UTIs in dogs are confirmed through a urinalysis, which checks for white blood cells, blood, and protein in the urine. In a healthy dog, there should be very few white blood cells present. When infection sets in, that count rises significantly, and blood and protein typically show up alongside it. Your vet will likely also run a urine culture to identify the specific bacteria involved, which helps guide treatment.
Uncomplicated UTIs are typically treated with a course of antibiotics lasting about 7 days, though some cases require up to 14. Most dogs show improvement within the first few days, and the fishy odor fades as the bacteria are cleared out.
It Might Not Be the Urine at All
Here’s something many dog owners don’t realize: the fishy smell may not actually be coming from the pee. Dogs have two small anal glands, one on each side of the anus, that produce a thick, oily secretion with an intensely fishy odor. These glands can leak or express when your dog squats to urinate, making it look and smell like the urine itself is the problem.
Anal gland fluid can drip onto the fur around your dog’s rear end and mix with urine on the ground, creating confusion about the source. If you notice your dog scooting across the floor, licking their rear end excessively, or if the fishy smell seems to come and go (rather than being present every single time they pee), anal glands are a strong suspect. Impacted or infected anal glands need to be expressed or treated by a vet, and chronic issues sometimes require changes in diet to add more fiber.
Vaginal Infections in Female Dogs
If your dog is female, a vaginal infection called vaginitis can produce discharge with a fishy smell that gets mixed in with urine during squatting. Common signs include frequent urination, licking the vaginal area, and discharge that may appear as mucus, pus, or occasionally blood. Some dogs will also scoot or rub their rear on the ground, similar to what you’d see with anal gland problems.
A more serious condition in unspayed female dogs is pyometra, an infection of the uterus that can produce foul-smelling discharge. Pyometra is a medical emergency. If your unspayed female dog has smelly discharge along with lethargy, loss of appetite, vomiting, or excessive thirst, she needs veterinary care immediately.
Bladder Stones and Recurring Odor
Bladder stones can create conditions where fishy-smelling urine keeps coming back even after treatment. In dogs, the most common type of bladder stone (struvite) is typically caused by UTIs and bacteria that change the chemical environment of the bladder. As these stones grow, bacteria get trapped between layers of the stone itself, making infections harder to fully eliminate with antibiotics alone.
If your dog has been treated for a UTI but the smell returns quickly, bladder stones may be harboring bacteria and reseeding the infection. Diagnosis usually involves an X-ray or ultrasound. Depending on size and type, stones may dissolve with a prescription diet or require surgical removal.
Kidney Problems Smell Different
Some dog owners worry that fishy urine means kidney failure, but kidney disease produces a different kind of odor. Dogs with failing kidneys develop breath and urine that smells strongly of ammonia, not fish. That ammonia smell comes from waste products building up in the blood that the kidneys can no longer filter out. Other signs of kidney trouble include very pale gums, mouth ulcers, and in advanced cases, blood in the urine. A fishy smell specifically points more toward bacterial infection or anal gland secretions than kidney disease.
What to Watch For
A one-time fishy smell after your dog pees isn’t necessarily an emergency, but persistent odor changes deserve attention. Certain signs alongside the smell mean you should get to a vet sooner rather than later:
- Straining to urinate without producing much urine, or crying while trying to go
- Blood in the urine, which may appear pink, red, or dark brown
- Inability to urinate at all, which is a true emergency requiring care within hours to prevent dangerous complications like a ruptured bladder
- Excessive thirst that seems impossible to satisfy, paired with frequent urination
- Lethargy, vomiting, or collapse alongside any urinary changes
If the fishy smell is the only symptom and your dog is otherwise acting normally, eating well, and urinating on a regular schedule, it’s still worth mentioning at your next vet visit. A simple urinalysis can rule out infection quickly and give you a clear answer about what’s going on.