TL;DR
The main symptoms of a urinary tract infection (UTI) in dogs are peeing often, straining, passing only small amounts, blood in the urine, accidents in the house, licking the genitals and a strong smell. Most UTIs are bladder infections (bacterial cystitis), and E. coli is the most common cause. A vet confirms it with a urine test, ideally a culture, because the same signs also come from bladder stones, crystals, bladder tumors and diabetes. International guidelines (ISCAID 2019) recommend a short course of antibiotics for a simple bladder infection and usually no antibiotics for bacteria found in the urine of a dog with no signs. Stones matter too: in 10,444 stones analyzed in the US, 47.0% were calcium oxalate and 43.6% struvite. Cranberry has not been shown to prevent UTIs in dogs. A dog that strains and produces no urine at all needs a vet immediately.
Symptoms of a UTI in dogs
| Symptom | What you might notice |
|---|---|
| Peeing more often | Asking to go out again and again |
| Straining | Squatting or lifting the leg for a long time |
| Small amounts | A few drops each time |
| Blood in the urine | Pink, red or brown urine, or spots on bedding |
| Accidents | Peeing indoors in a house-trained dog |
| Licking | Frequent licking of the genital area |
| Smell | Strong or unusual urine smell |
| Discomfort | Whining or restlessness when peeing |
Some dogs, especially older dogs and dogs on steroids, show no signs at all, and the infection is only found on a routine urine test.
Signs of a more serious infection
A kidney infection (pyelonephritis) or prostate infection can cause fever, lethargy, poor appetite, vomiting and back pain. These need prompt treatment.
Emergency: straining with no urine
A dog, especially a male, that strains but produces no urine may have a stone blocking the urethra. This is an emergency: a blocked bladder can rupture and the kidneys can fail within a day or two.
What causes UTIs?
Bacteria from the skin and gut travel up the urethra into the bladder. E. coli is the most common culprit. Things that make infection more likely:
- Being female. A shorter, wider urethra makes it easier for bacteria to get in.
- Diabetes. In a UK study of 439 diabetic dogs, a diagnosis of UTI was positively associated with diabetes.
- Cushing's disease and long-term steroid use.
- Bladder stones, which irritate the bladder and harbor bacteria.
- Skin folds around the vulva, common in overweight dogs.
- Incontinence and problems emptying the bladder fully, for example after spinal disease.
- Older age.
Bladder stones: the look-alike
Stones cause the same signs as an infection, and the two often go together.
In 10,444 stones from dogs analyzed at UC Davis between 2006 and 2018:
- Calcium oxalate: 47.0%
- Struvite: 43.6%
- Cystine: 2.7%, rising from 1.4% to 8.7% over the period, mostly in intact males
The type matters for treatment. In dogs, struvite stones are usually caused by infection and can often be dissolved with a special diet and antibiotics. Calcium oxalate stones cannot be dissolved and have to be removed.
A small-animal vet Morty has known for years, who asked us not to use their name, sees stones most in Schnauzers: "Once a stone has formed, it most likely needs surgery to remove; it will not go away on its own. Prevent it: plenty of water, plenty of exercise, and don't make them hold their urine." See Miniature Schnauzer lifespan.
How vets diagnose a UTI
- Urinalysis: looks for blood, white cells, bacteria and crystals.
- Urine culture: grows the bacteria and shows which antibiotic will work. The ISCAID guidelines recommend culture, especially for recurrent infections.
- X-rays or ultrasound: to look for stones, tumors or other problems if infections keep coming back.
- Blood tests: to look for diabetes, Cushing's or kidney disease in dogs with recurrent UTIs.
The best urine sample for culture is taken straight from the bladder with a fine needle (cystocentesis). It sounds alarming but is quick and well tolerated.
Treatment
The ISCAID 2019 guidelines, written by an international panel of specialists, recommend:
- Simple bladder infection (sporadic cystitis): a short course of antibiotics, typically 3 to 5 days, plus pain relief.
- Recurrent infections: a urine culture and a search for the underlying cause.
- Bacteria in the urine without any signs (subclinical bacteriuria): usually no antibiotics, because treatment does not help and breeds resistance.
- Kidney infection: a longer course of antibiotics.
Does cranberry help?
Not on current evidence. A 2026 systematic review found only three studies, covering 106 dogs and 16 cats, and none showed an effect of cranberry on preventing or treating urinary infections.
How to lower the risk
- Plenty of fresh water, in several bowls around the house.
- Frequent toilet breaks. Don't make your dog hold its urine for long periods.
- Keep your dog lean, which reduces skin folds around the vulva and diabetes risk. See senior dog food for weight loss.
- Keep the genital area clean in long-haired and older dogs.
- Treat the underlying cause in dogs with diabetes, Cushing's or stones.
FAQ
What are the first signs of a UTI in a dog?
Peeing more often, straining, passing small amounts and having accidents indoors. Blood in the urine and licking the genitals are also common.
Can a dog UTI go away on its own?
Mild infections occasionally clear, but it is not worth the risk: an untreated infection can spread to the kidneys, and the same signs can come from stones or tumors. A urine test gives the answer.
How long does it take antibiotics to work for a dog UTI?
Most dogs feel better within a day or two. International guidelines recommend a short course, typically 3 to 5 days, for a simple bladder infection.
Why does my dog keep getting UTIs?
Recurrent infections usually have a cause: stones, diabetes, Cushing's disease, skin folds, incontinence or a problem emptying the bladder. A urine culture and imaging help find it.
Does cranberry prevent UTIs in dogs?
There is no good evidence that it does. A 2026 systematic review found no effect in any of the three studies available.
References
- Weese JS, et al. International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. The Veterinary Journal. 2019. PMID: 30971357
- Kopecny L, et al. Urolithiasis in dogs: evaluation of trends in urolith composition and risk factors (2006-2018). Journal of Veterinary Internal Medicine. 2021. PMID: 33960543
- Weese JS, Weese HE. Effectiveness of cranberry supplementation for prevention and treatment of infectious urinary tract disease in dogs and cats: a systematic review. Journal of Veterinary Pharmacology and Therapeutics. 2026. PMID: 41676867
- Mattin M, et al. An epidemiological study of diabetes mellitus in dogs attending first opinion practice in the UK. Veterinary Record. 2014. PMID: 24570406
For individual health questions, your veterinarian remains the best partner.
