Urinary Tract Infection

Urinary Tract Infection

Urinary tract infections (UTIs) are common in both dogs and cats. Urinary tract infections are only one of the many health concerns involving the urinary tract and many of these concerns involve the same symptoms. If you think your pet is suffering from a UTI, an exam, urinalysis and urine culture will be needed to determine if it is truly a urinary tract infection.




Some of the commonly noted symptoms of a pet with a urinary tract infection include:

  • frequent urination, usually only small amounts of urine is produced each time they urinate
  • blood in the urine
  • inappropriate urination or incontinence (unable to make it to the litter box or outside to go)
  • urine produced has a strong smell

These symptoms are also common symptoms for other urinary health concerns, including urinary blockages, bladder stones and bladder tumors.


Diagnosis of a urinary tract infection usually begins with running a urinalysis on a sample of your pet’s urine and then sending the urine to the outside laboratory for culture and sensitivity testing.

Urine Collection

There are various ways of collecting the sample, but in the case of a UTI, a sample obtained by cystocentisis is ideal. This is when the urine is collected by using a needle and syringe directly into the bladder. By collecting the urine this way any bacteria present is true to being in the urine, and not from outside source contamination. If a cystocentisis is not possible urine can also be collected by free catch or in male dogs, by catheter.


Running a urinalysis on your pet’s urine sample consists of 4 parts: the gross examination, specific gravity, urine chemistry stick and sediment evaluation.

Refractometer, urine sample, urine chemistry sticks, sediment slide

Refractometer, urine sample, urine chemistry sticks, sediment slide

Gross Examination: This evaluates the physical appearance of your pet’s urine. The color, odor and turbidity of the urine sample is recorded. Urine from a pet with a UTI will usually have urine that is turbid (not clear), smelly and may have a green or brown tinge to it.

Specific Gravity: The specific gravity is measured using a refractometer. The specific gravity of your pet’s urine gives an indication of your pet’s kidney function. It lets the veterinarian know how well (or not well) your pet is able to concentrate their urine. If the UTI is affecting the kidneys as well, the specific gravity may be lower than normal.

Urine Chemistry Stick: The chemistry stick analyses the chemical properties of your pet’s urine. The presence of white blood cells, red blood cells, nitrite, urobilinogen, protein, pH, ketones, billirubin and glucose are all checked with the chemistry stick. In the case of a urinary tract infection the chemistry stick will usually be positive for white blood cells and protein.

Sediment Evaluation: After the urine is spun down in the centrifuge, the sediment can be evaluated. The centrifugation allows us to concentrate things in the urine for evaluation under the microscope. We look for the presence and amount of white and red blood cells, epithelial cells, crystals, casts and bacteria. When evaluating the sediment from an infected urine sample white blood cells, bacteria and possibly red blood cells will be seen.

Urine Culture and Sensitivity

Urinary tract infections can sometimes be difficult to treat and bacteria can become resistant if treatment is not effective from the beginning. Therefore, if a UTI is seen on the urinalysis, a culture and sensitivity test will be recommended. By sending the urine sample to the lab they will culture (grow) the bacteria and test it against a bunch of varying antibiotics.  The report will let us know what type of bacteria is present and what antibiotics the bacteria is sensitive and resistant to.  This will allow us to pinpoint an exact antibiotic that the bacteria is sensitive to in order to treat the infection effectively.

Treatment and Monitoring


Initially treatment is started by prescribing a broad spectrum antibiotic. Our hope is that the bacteria is sensitive to the chosen antibiotic. Once the culture and sensitivity results are received the veterinarian will decide whether or not to extend the current antibiotic prescription, change antibiotics or add in a second antibiotic to the treatment. Treatment with antibiotics is usually 2-3 weeks, however persistent infections may take up to 6 weeks to treat.

Repeat Urinalysis and Culture

After the course of antibiotics is complete, we recommend waiting 2-4 days, then repeating the urinalysis and culture. This will let us know if the infection is cleared up or still persisting. If it is cleared up, great! No further treatment is needed. If the UTI is still persisting, then the prescription of antibiotics will be extended or changed to another antibiotic that the bacteria is sensitive to.

Some pets are more prone to urinary tract infections than others, these include:

Female animals: They have shorter and wider urethral openings, making it easier for bacteria to enter the urinary tract.

Pets with other urinary tract disorders: The presence of bladder stones or bladder cancer can predispose them to developing UTIs.

Diabetes and Cushing’s Disease: If your pet has either of these diseases, they might have increased levels of sugar in their urine. This is the perfect environment for bacteria to grow and flourish, making your pet at risk for re-occurring urinary tract infections.

Suppressed immune system: Pets with a suppressed immune system from either taking immuno-supressive drugs, old age or other health concern can be more susceptible to urinary tract infections since their immune system is not functioning at 100%.