Urinary Tract Infections (UTIs) in Dogs

By Courtney Barnes, BSc, DVMMalcolm Weir, DVM, MSc, MPH; Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP

My dog suddenly started asking to go outside very frequently. A sample of urine revealed a bladder infection. How did this happen?

Urinary tract infections (UTIs) are fairly common in dogs. Dogs with UTIs generally attempt to urinate frequently, whenever they go outside. They also may strain to urinate, or cry or whine when urinating, as it can be painful. Sometimes blood may be visible in their urine. Dripping urine, or frequent licking of the genitals, may also signal that a UTI is present. Urine that has a very strong odor can also be a sign that your dog has an infection.

A break in house training is a red flag that something is wrong in the bladder. If this happens to your previously well-mannered dog, a UTI may be to blame.

Generally, a UTI occurs when bacteria travel up the urethra (the tube through which urine exits the body) and into the bladder. Urine in the bladder is sterile, but once bacteria find their way there, they can grow and reproduce, causing a UTI. Additionally, some dogs will develop bladder stones in conjunction with their UTI, which opens the door for additional health issues.

What does a urinalysis look at?

If your dog presents to your veterinarian with urinary signs, your veterinarian will first perform a urinalysis. There are several urinary tract disorders that can mimic the signs of a UTI, so it is important to do this test. The urinalysis reveals important information about the urine. Your veterinarian will look at the following:

  • urine-specific gravity (how well the dog is concentrating their urine)
  • pH (certain pH levels can indicate infection or other problems)
  • ketones (sometimes seen in cases of diabetes or body-wasting)
  • glucose (sugar in the urine, usually a sign of diabetes)
  • bilirubin (a breakdown product of blood)
  • blood
  • protein

Once these levels are measured, the urine sample is “spun down” in a machine called a centrifuge to allow cells and other debris to accumulate at the bottom of the sample tube. That debris can then be evaluated under a microscope.  This examination can reveal the presence of red blood cells, white blood cells, bacteria, and crystals.

What is seen under the microscope’s magnification can lead to the next steps in assessing the dog’s urinary tract disease. For example, if there are crystals in the urine, your veterinarian may recommend X-rays or an ultrasound of the abdomen to look for bladder stones.

My veterinarian sent a urine sample to a laboratory for a culture and sensitivity test. What is this test?

All urinary tract infections are different. The most common organism to cause UTIs in dogs is Escherichia coli (a bacteria found in feces), but there are many other possibilities. Sometimes there is more than one type of bacteria involved in the infection. The only way to identify which bacteria is involved is to grow it in a laboratory. At the same time, the lab can also test which antibiotic is best suited to treat the infection.

The only way to identify which bacteria is involved is to grow it in a laboratory."

Often, a veterinarian will prescribe an antibiotic that should be effective against most common bacteria (first line drug) to try to provide immediate relief to the dog. Pain medication may also be prescribed, as UTIs can be uncomfortable, and a diet change may be recommended.

Once the culture and sensitivity results are received, your veterinarian may change the antibiotic if a more appropriate medication is identified. After the course of antibiotics is completed, it is important to recheck the urinalysis to confirm that the infection is resolved. If it is not, then it is important to investigate additional issues that may contribute to a persistent UTI.

If the infection is not treated, your dog will experience ongoing discomfort. Complications can also occur, such as bladder stones or a kidney infection called pyelonephritis.

Are some dogs predisposed to UTIs?

Female dogs are more prone to UTIs than male dogs due to their smaller, wider urethras. Older female dogs, young puppies, and obese dogs are more represented among dogs with UTIs, though dogs of any age and sex can be affected.

"If predisposing factors are not addressed, UTIs can become difficult to resolve and may be a recurring problem."

Certain medical conditions can predispose a dog to UTIs, including diabetes mellitus (sugar diabetes), kidney disease, hyperadrenocorticism (Cushings’s disease), bladder cancer, incontinence, and immunosuppression. Dogs with bladder stones are also more prone to recurrent UTIs.

The variety of underlying causes of UTIs highlights the importance of getting a complete diagnosis whenever there is evidence of disease in the urinary tract. Bladder stones must be removed or dissolved to restore bladder health.

Certain anatomic issues can also predispose a dog to UTIs, such as ectopic ureters or, in female dogs, a recessed vulva (the vulva is covered by skin folds). If predisposing factors are not addressed, UTIs can become difficult to resolve and may be a recurring problem.

What can I do to prevent a UTI from occurring in the future?

Your veterinarian will inform you if anything can be done to prevent your dog’s UTI from recurring. Often, a diet change may be recommended. They may also recommend some medications or supplements that can make it harder for an infection to take hold. It is best to discuss UTI prevention and bladder health with your veterinarian to enact an effective plan.

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