Canine Urinary Tract Infections (UTI)

Posted by  on June 15, 2010

If your dog is having trouble urinating or is going more often than normal, it’s possible he or she has a urinary tract infection.  Read on to find out all of the symptoms, causes, and treatment options to help your dog overcome this sometimes painful condition.

Urinary Tract Anatomy and Function

The upper portion of a dog’s urinary tract consists of the kidneys and ureters, while the lower tract is comprised of the bladder and urethra.  In males, the urethra is surrounded by the prostate gland.  The urethra of females is shorter and wider, making them more susceptible to UTIs.  Older dogs, especially if they are spayed, are especially vulnerable.

The purpose of the kidneys is to filter out waste products from the blood and remove excess water from the body.  The products left in the kidney tubules after filtration are sent to the ureters, which convey the urine to the bladder.

The bladder is a sort of holding tank that stores urine until the dog is taken outside to do his business, under the best of circumstances.  If your dog has an infection, he or she may not make it outside in time.  When the bladder gets too full, or if it is irritated, its smooth muscles contract, expelling the urine to the urethra, which is a tube that carries the urine to the outside of the body.

Names and Causes of Urinary Tract Infections

The urinary tract is supposed to be completely free from bacteria, but in about 2 – 3% of dogs, it can be invaded by something that causes infection.  Most commonly, bacteria enter the urinary tract through the urethra and travel up along the tract.  Depending on when the infection is discovered and how effectively it is treated, the infection may be stopped along the lower portion of the tract, or it may travel on as far as the kidneys at the top of the urinary tract.

An infection may involve several parts of the urinary tract, or it may settle in just one area.  The name of the infection is determined by the portion of the tract where the primary infection resides, as shown below:

  • Urethra:  urethritis
  • Prostate:  prostatitis
  • Bladder:  cystitis
  • Ureters:  ureteritis
  • Kidneys:  pyelonephritis

When bacteria is being shed in the urine, the condition is known as bacteriuria.

Other than infections traveling up from the urethra, your dog could also be infected by other means.  For example, a kidney stone is seen by the dog’s body as a foreign object.  The dog’s immune system reacts to it by mounting an immune response similar to that seen in a bacterial infection.

Conversely, infections can cause the urine to crystallize and form into stones anywhere in the urinary tract.  As the infection progresses, inflammation causes the urethra to become narrow, allowing less urine to pass through.  The urine that remains behind becomes stagnant and begins to crystallize into urinary stones.

In the lower urinary tract, obstructions and birth defects can cause infections by allowing urine to pool and become stagnant.  Although infections of the lower tract are uncomfortable for your dog, they are not as dangerous as upper tract infections, which can harm the kidneys and permanently impair kidney function.

Leaving urine in the bladder for an extended period of time can cause the urine to fester, creating an infection.  Your dog should be encouraged to empty his or her bladder several times each day.  If you can’t be home, be sure to provide an area indoors for elimination or hire someone to walk your dog during the day.

How do I know if my dog has a urinary tract infection?

Although the symptoms of urinary tract infections vary, they share the characteristic that they all have names designed to confuse the average pet guardian.  You may hear your veterinarian talk about dysuria, pollakiuria, polyuria, polydipsia, pyuria, hematuria, or even crystalluria.  Confused yet?  Below is a handy-dandy guide to UTI symptoms from

Dysuria: pain on urination or difficulty passing urine

Pollakiuria: increased frequency

Polyuria: increased volume

Polydipsia: excessive thirst

Pyuria: pus in the urine

Hematuria: blood in the urine

Crystalluria: crystals in the urine.

Your dog may show dysuria by pacing and whining near the door where he or she is used to being let out, even if the dog has just come in from outside.  Your dog will be embarrassed by breaking his house-training, but he or she may not be able to help it.  It is likely he or she will seek an out-of-the-way place to empty the bladder such as under your bed or in a corner.  If it is unlike your dog to urinate in the house, it can be an important indicator of a urinary tract problem.

Other common symptoms of urinary tract infection are a tender lower abdomen, foul-smelling urine, and lower back pain, which your dog may show by having trouble standing up or shying away from you when you try to pet him or her.

Your vet’s job is to distinguish between infections and other diseases that can cause these same symptoms such as kidney stones, urinary tract cancers, benign prostate growth, diabetes, and urinary obstruction.  Part of the diagnosis depends on the age and breed of the dog, as different diseases are more common in certain breeds and at different ages.

Diagnosis of UTI

The diagnostic evaluation of a dog with urinary symptoms generally starts with a urinalysis.  Even if you can’t see it, dogs with an infection might have microscopic traces of red blood, white blood cells, or pus in the urine.  Your vet may ask you to bring a urine sample, and collecting one can be difficult particularly if your dog has short legs.

The easiest way to collect urine is to carry a large serving spoon and a plastic cup while you follow your dog around the yard or on a walk.  As soon as the dog squats or lifts his leg, position the spoon to catch the urine stream.  Fill the spoon as much as possible, then dump it into the cup.  Your vet will not need very much urine to test, so one spoonful should be fine.

Your vet will also ask you questions about how often your dog is urinating, whether or not he or she seems to be in pain when passing urine, and when you first noticed the symptoms.

He will feel the bladder through the dog’s abdominal wall, examine the dog’s genitalia, and possibly feel inside the dog’s rectum to check the urethra and prostate. If kidney stones are suspected, he may want to do some X-ray studies to look for them.

Treatment and Prevention of Canine UTI

Traditional treatment for urinary tract infections involves one of two common types of antibiotics:  sulfonamides or fluoroquinolones.  Each is effective against different types of bacteria, and each has specific side effects that may or may not be tolerable for your dog.  Homeopathic, natural remedies are also available.

At home, make sure your dog has access to clean, healthy food and fresh water to help prevent urinary tract infections.  The more your dog drinks the better, as excess liquids will travel through the urinary tract, helping to flush out bacteria.  Mixing fruit juices, especially cranberry juice, with your dog’s water may help to make the urine more acid which can help prevent infections and urinary stones.

Walking and playing also stimulate your dog’s bladder, encouraging him or her to eliminate urine.  The more frequently urine is passed, the less likely it is to sit and become infected anywhere along the urinary tract.

If your dog begins to show signs of painful urination, or if you notice blood in the urine, you might try a day or two of home treatment such as frequent walking, cranberry juice, and encouraging him to drink a lot of water.  However, if the symptoms persist for longer than a day or two, professional treatment including antibiotics is warranted to prevent the infection from getting worse, as well as to keep your dog happy and reduce his or her pain.