Urinary tract infection in dogs

Symptoms an owner can spot at home

• Frequent attempts to urinate, producing only small volumes each time
• Straining or obvious discomfort while urinating
• Blood-tinged or unusually strong-smelling urine
• Accidents indoors in a reliably house-trained dog
• Excessive licking of the genital area

When to see a vet

• Straining with little or no urine produced is an emergency; urinary obstruction is life-threatening within hours
• Any urinary sign in a male dog, obstruction risk is higher and the cause list is different
• Fever, vomiting, back or flank pain, or lethargy, these suggest the kidneys are involved (pyelonephritis)
• Visible blood in the urine
• A third urinary episode within a year, recurrence means the workup should widen, not repeat

What it is

Most canine urinary tract infections are ascending bacterial cystitis: organisms from the perineal and lower genital area travel up the urethra and colonise the bladder. Escherichia coli is by far the most frequent isolate, with Staphylococcus, Proteus, Enterococcus, Klebsiella, and Streptococcus species accounting for most of the remainder. Female dogs are affected more often, a consequence of a shorter, wider urethra.

The clinically useful split is sporadic versus recurrent. A sporadic episode in an otherwise healthy dog is treated and closed out. Recurrent infection, generally three or more episodes in a year, is a different problem: it points toward an underlying driver such as urolithiasis, diabetes mellitus or hyperadrenocorticism, an anatomic issue like a recessed vulva, incomplete bladder emptying, or bladder wall disease. Repeating a course of antibiotics without finding that driver produces exactly the pattern owners describe as 'it keeps coming back'.

Subclinical bacteriuria, bacteria in the urine of a dog with no clinical signs, is a separate category again. International guidance is generally not to treat it in most patients, because treatment does not benefit the dog and does drive resistance.

How vets diagnose it

A urinalysis on a properly collected sample is the foundation, with cystocentesis (needle collection directly from the bladder) preferred because free-catch samples pick up contaminants. Urine culture with antimicrobial susceptibility testing identifies the organism and the right drug; ISCAID guidance recommends culture particularly for recurrent, complicated, or treatment-failure cases rather than guessing twice.

• Imaging (ultrasound or radiographs) looks for bladder stones, masses, and prostatic disease.
• Bloodwork screens for the endocrine diseases that predispose to recurrence.
• Urine specific gravity gives an early clue to concurrent renal disease or diabetes.

Treatment overview

This is editorial overview, not a treatment plan; your vet builds the plan. Sporadic bacterial cystitis is treated with a short, targeted antibiotic course; contemporary ISCAID guidance favours shorter durations than the multi-week courses once standard, because they work and they spare selection pressure for resistance. Complicated or upper-tract infections need longer treatment and culture-guided drug choice.

Cranberry-based supplements, D-mannose, and urinary acidifiers are widely sold; evidence in dogs is limited and none of them substitutes for culture-directed therapy in an active infection. Where stones are present, diet becomes therapeutic rather than supportive and is prescribed by stone type.

What owners can do

• Drive water intake up. Dilute urine is the cheapest prophylaxis there is: a clean bowl in every room, a circulating fountain if your dog prefers moving water, and wet food or water added to kibble.
• Increase toilet opportunities. Urine held for a full working day gives bacteria more contact time with the bladder wall.
• Keep the perineal area clean and clipped in long-coated or overweight dogs; a recessed or skin-folded vulva is a genuine risk factor.
• Wash bowls daily and choose stainless steel or ceramic over scratched plastic, which harbours biofilm.
• Finish the full prescribed course even after signs disappear, and never reuse leftover antibiotics from a previous episode.
• Log the episodes with dates. Three in twelve months is a threshold that changes the workup, and only a written record makes it visible.