How Vets Diagnose UTIs in Dogs
There are many ways to tell if a dog has a UTI and to investigate the underlying causes for why an infection occurred in the first place. It’s important to obtain a definitive diagnosis whenever there is evidence of urinary tract disease, or else UTIs may come back.
Here are the ways that veterinarians test for UTIs in dogs.
Urine Collection
There are four methods by which your vet may collect your dog’s urine for UTI testing:
-
Free catch is when the urine is caught directly as your dog pees.
-
Tabletop is collecting urine after your dog pees a surface, such as a table.
-
Cystocentesis is sterilely collecting urine via a needle, suctioning it directly from the bladder. (Oftentimes, this is guided by an ultrasound.)
-
Urethral catheterization is urine collection via a catheter that’s inserted sterilely.
The best option is cystocentesis, as the most sterile way to obtain a urine sample is directly from the bladder. Remember: Because a large number of bacteria normally live in the environment and on a dog’s external genitalia, tabletop and free-catch sampling may reveal other bacterial contamination that makes it difficult to determine if there is truly a UTI.
Urine Testing
There are two main ways your vet can test your dog’s urine for UTIs.
1. Urinalysis
Urinalysis is an important screening tool for dogs, whether a UTI is suspected or not. It is often part of the baseline testing performed on your dog during their annual health examination.
Urinalysis is a general screening test, which examines urine for the following:
-
pH
-
Specific gravity (a measurement of the concentrating ability of the kidneys)
-
Protein
-
Blood
-
White blood cells
-
Glucose (sugar)
-
Ketones (compounds produced by fat breakdown in the body)
-
Particles such as cells, bacteria, and crystals
Most commonly, vets diagnose UTIs in dogs by finding elevated counts of white blood cells, blood, and protein in the urine, and a low urine specific gravity. Bacteria are not always seen in urine samples in the early stages of a UTI, as the white blood cells can ingest them, effectively hiding them from microscopic sight.
2. Urine Culture and Susceptibility (or Sensitivity) Test
A urine culture and susceptibility test is the gold standard for UTI diagnosis and the only test that can truly confirm a UTI in dogs. If your vet suspects your dog has a UTI, they should obtain a sterile urine sample by cystocentesis and send it out for a culture and sensitivity test.
To perform this test, vets incubate a small amount of the urine sample on a special medium plate and monitor it for bacterial growth over 1-3 days. Any growth of bacteria on the medium plate confirms a UTI.
Culture and susceptibility tests also reveal the type and amount of bacteria in the sample. Once this is confirmed, your vet performs antibiotic sensitivity testing to determine which antibiotics are best to treat the type of bacteria present.
Diagnosing Acute UTIs
For acute UTIs, many veterinarians will start with a urinalysis and will sometimes even treat it with a broad-spectrum antibiotic. A urine culture and sensitivity test is more reliable, though, and your vet should conduct it before treatment if there is any doubt as to whether a UTI is present.
Treatment with an inappropriate antibiotic or giving your dog an antibiotic without a diagnosed UTI can be detrimental, as it can lead to antibiotic resistance in the future.
Diagnosing Chronic UTIs
For chronic UTIs, your dog will undergo both urinalysis and a urine culture. Often, your vet will perform even further diagnostic testing to investigate underlying causes for the recurrence of the UTI. These tests may include:
-
Full bloodwork to help to rule out kidney disease, Cushing’s disease, and diabetes mellitus as possible contributing factors.
-
Abdominal radiographs (x-rays), which can reveal certain types of bladder stones. However, some stones are not visible on x-rays.
-
Abdominal ultrasound to evaluate the bladder wall thickness and to identify bladder stones, urethral stones, kidney disease, kidney stones, prostate issues, tumors and benign polyps of the bladder, and prostate issues.
-
Cystoscopy, which provides direct visualization of the urethra and bladder lining through a sterile procedure performed under general anesthesia. Biopsies of any masses and/or the bladder wall can also be obtained via cystoscopy.