A urinalysis is a crucial part of routine care for your cat or dog. It can be used to ensure that your pet's systems are working as they should be. Here, our San Angelo vets talk about what a urinalysis performed in our diagnostics lab can show us and how we use this information.
What is a urinalysis?
A urinalysis tests the physical and chemical properties of urine. It can be used as part of regular preventive care and for diagnosing the cause of specific symptoms.
Why would a vet perform a urinalysis?
Your vet will use a urinalysis to detect the overall health of the kidneys and urinary system. It may also be used to determine issues in other organs such as the liver.
How is urine collected for urinalysis?
There are three different ways that your vet may collect your pet's urine sample:
Cystocentesis: This process uses a sterile needle and syringe to puncture the abdominal wall and collect the urine directly from the bladder. This method allows the urine to be collected without possible contamination from debris within the lower urinary passage. Cystocentesis is most commonly used when detecting bacterial infections and other issues with the kidneys and bladder. Unfortunately, this method can only be used when your dog has a full bladder and is cooperative.
Catheterization: This method of urine collection uses a catheter passed through the urethra and up into the bladder to extract urine. This option may be easier than cystocentesis as it is less invasive and easier to use. The downside is the possible irritation that may occur in the urethra and the chance of bacteria moving from the urethra and into the bladder during the process.
Mid-stream free flow: Collecting your dog or cat's urine as they relieve themselves is the easiest method of collection. It is called mid-stream free flow because it is recommended that the urine is collected halfway through their voiding. You can even collect the urine in your own time. There is the possibility, however, that the sample could become contaminated during collection.
What happens during the urinalysis?
There are four distinct parts of urinalysis, they are:
- The assessment of the urine for cloudiness.
- Measuring the concentration of the urine.
- Gauging the acidity or PH of the urine.
- Microscopic examination of the cells and solid material present in the urine.
Generally, the urine will be examined as a whole specimen just as it was collected. However, if your vet decides to complete a microscopic examination of the cells and solid material, they will need the urine sample to be concentrated or sedimented. To create a concentrated urine sample, your vet will place the sample of your pet's urine in a tube and run it through the centrifuge at very high speeds. This will cause the heavier materials to move to the bottom of the sample for analysis using a microscope.
How will the vet perform a chemical analysis?
A chemical analysis is completed using a dipstick. A dipstick is a small strip of plastic that holds a series of individual test pads. The pads used in the dipstick are designed to change color depending on the concentration of different elements in the urine. The dipstick is dipped into the urine, and after a short waiting period, the color of the test pads is compared to a chart that translates the intensity of the color to an actual measurement.
What are the different substances found in urine?
- Protein: The presence of protein in urine is called proteinuria. While trace amounts of proteinuria found in concentrated urine may not cause your vet to worry, proteinuria in dilute urine should be considered dangerous since it may indicate kidney disease. The significance of proteinuria is often determined by doing a second test called the protein creatinine ratio test.
- Glucose: Your vet should not find any glucose in your pet's urine. The presence of large amounts of glucose usually indicates your pet has diabetes. Small amounts of glucose in the urine may also be found in pets with kidney disease.
- Ketones: When your pet's body begins to break down stored fats as an energy source, it can result in the presence of ketones. This occurs most frequently in diabetes, but can also be found in healthy animals during prolonged fasting or starvation.
- Blood: If blood is found in the sample, it means that your dog or cat is experiencing bleeding somewhere within their urinary system. Sometimes this is due to how the sample was collected. For example, small amounts of blood are often found in samples collected by cystocentesis or catheterization. Blood in the urine is associated with diseases such as bacterial infection, bladder stones, trauma, or cancer. So if the blood in the urine does not appear to be due to the sampling method, further investigation is recommended.
- Hemoglobin: If your pet has hemolytic anemia, it can result in blood in the urine. Hemolytic anemia is when red blood cells are destroyed and a protein called hemoglobin is released. Hemoglobin passes into the urine and causes the blood test pad to show positive, even though there is no actual bleeding in the urinary system.
- Myoglobin: There is also the chance that blood may be present if your pet is experiencing trauma such as a torn muscle or ligament. This is because damaged muscle fibers release a protein called myoglobin, which is very similar to hemoglobin. Myoglobin will also cause the blood test pad to show positive, even though there is no actual bleeding in the urinary system. A specific test for myoglobin can be done if muscle injury is suspected.
- Urobilinogen: The presence of urobilinogen in urine indicates that the bile duct is open, and that bile can flow from the gallbladder into the intestine.
- Bilirubin: Bilirubin is a substance produced in the liver and normally excreted in the bile. Bilirubin is not found in the urine of healthy cats but may be found in small quantities in the urine of healthy dogs. Abnormal amounts of bilirubin in the urine are associated with liver disease or red blood cell destruction (called hemolysis), and should always be investigated.
What can be found in the urine sediment?
Urine sediment is commonly made up of red blood cells, white blood cells, crystals, bacteria, and tissue cells from different parts of the urinary system. There may be small amounts of other particles, including mucus, present in this sediment. Your vet may even discover parasitic eggs.
- Red Blood Cells: Small numbers of red blood cells are often found in urine collected by cystocentesis or catheterization, but large numbers of red blood cells usually indicate bleeding. This may be caused by conditions such as bladder stones, infection, coagulation problems, trauma, cancer, and much more.
- White Blood Cells: Small numbers of white blood cells in a free-catch sample may not be significant, but a large number of white blood cells indicate inflammation somewhere in the urinary system. Inflammation is often secondary to bacterial infection.
- Bacteria: The presence of both bacteria and inflammatory cells in the sediment indicates there is likely bacterial infection somewhere in the urinary system. Ideally, the urine should be sent to the laboratory for culture and sensitivity testing to find out what types of bacteria are present. This also helps determine what antibiotic should be used to treat the infection.
Crystals. There are many different types of crystals and they vary in size, shape, and color. The significance of crystals also varies. Some crystals are unique and help to pinpoint a specific diagnosis. In more common conditions such as bladder infection and bladder stones, the crystals provide information that can influence how the disease is managed.
Crystals in the urine do not always indicate disease. Some crystals form when a pet is given certain types of medications. Crystals can also form in urine after it has been collected, especially if there is a long delay before the urinalysis is done. If this happens, your veterinarian may wish to examine a fresh sample immediately after it has been collected to determine if the crystals are significant.
- Tissue Cells: Increased numbers of tissue cells are often seen in samples collected by catheterization. While this is not a sign of disease, increased cellularity can be seen with a variety of disorders, including urinary tract inflammation, bladder stones, prostate problems (in male pets), cancer, and more.
Urine samples are a crucial part of diagnosis for both determining the cause of particular symptoms and monitoring your cat or dog's ongoing health and bodily function.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.