Why Dogs Get UTIs
Most urinary tract infections (UTIs) are caused by bacteria ascending through the urethra into the bladder — most commonly Escherichia coli, followed by Staphylococcus, Proteus and Enterococcus. The bladder's natural defences (frequent urination, an intact mucous lining, urine acidity) usually keep bacteria at bay, but certain conditions can tip the balance.
Risk Factors
- Sex: female dogs are more susceptible due to their shorter urethra.
- Age: older dogs have weakened immune function and, in females, lower oestrogen.
- Hormonal status: spayed females lose oestrogen that helps maintain urethral tone.
- Underlying disease: diabetes mellitus (glucose in urine feeds bacteria), Cushing's syndrome, chronic kidney disease and immunosuppressive drugs all raise risk.
- Bladder stones: create microtrauma that bacteria exploit.
- Anatomical anomalies: vulval fold pyoderma, ectopic ureter, persistent hymen.
Recognising the Symptoms
- Straining to urinate (dysuria) or vocalising during urination.
- Frequent urination in very small amounts (pollakiuria).
- Blood-tinged urine (haematuria) — from pink to frank red.
- Excessive licking of the vulva or prepuce.
- House-training accidents in a previously reliable dog.
- Fever, lethargy, loss of appetite, back pain → possible kidney involvement (pyelonephritis — more urgent).
Diagnosis
Your vet will collect a urine sample — ideally by cystocentesis (a sterile needle directly into the bladder) to avoid contamination. Tests include:
- Urinalysis: check for white blood cells, red blood cells, bacteria, pH and protein.
- Urine culture and sensitivity: identifies the bacteria and determines which antibiotic will work. Do not skip this step — random antibiotic use drives resistance.
- Abdominal ultrasound or X-ray: rules out bladder stones, masses, or anatomical anomalies especially in recurrent cases.
Treatment
Antibiotics are the cornerstone treatment, selected based on culture results — commonly amoxicillin-clavulanate, trimethoprim-sulphamethoxazole or enrofloxacin. Duration is typically 7–14 days for simple cystitis and 4–6 weeks for complex infections. Always complete the full course. A follow-up urine culture 5–7 days after finishing antibiotics confirms resolution.
Increase water intake (wet food, a drinking fountain, extra water bowls) to encourage more frequent urination and flush the bladder.
Recurrent UTIs
More than two infections per year warrants a thorough work-up: imaging for stones or masses, checking for underlying conditions (diabetes, Cushing's), and review of anatomy. Some dogs benefit from urinary antiseptic supplements (D-mannose, cranberry extract) as prevention — the evidence is modest but they carry little risk.
When to Go to the Emergency Vet
- Complete inability to urinate (urinary obstruction — more common in male cats but can occur in dogs).
- Fever above 39.5 °C combined with urinary symptoms.
- Visible distress, crying when touched near the lower back/abdomen.
- Blood clots in the urine.
Log your dog's urinary health — episodes, dates, lab results and treatments — in Purzi. Having this history to hand at the vet visit saves time and helps spot patterns in recurrent cases.