At Harris Parkway Animal Hospital, we believe strongly in educating our clients so they can be the best possible pet owners. So today, our Fort Worth vets will discuss urinalysis for dogs and cats, as well as how to understand your pet's urinalysis results so you can make the best decisions regarding their medical care.
What is a Urinalysis?
A urinalysis is a simple diagnostic test that determines the physical and chemical properties of urine. It is primarily used to evaluate the health of the kidneys and urinary system, but it can also reveal issues with other organ systems. All pets eight years of age and older should have a yearly urinalysis. A urinalysis may also be recommended if your pet has increased water intake, increased frequency of urination, or visible blood in the urine.
How is Urine Collected?
There are three main ways to collect urine from cats and dogs:
Cystocentesis: A sterile needle and syringe are used to collect urine from the bladder. The urine is not contaminated by debris from the lower urinary tract after cystocentesis. This specimen is ideal for assessing the bladder and kidneys, as well as detecting bacterial infection. The procedure is slightly more invasive than others and is only useful if the bladder of the pet is full.
Catheterization: Catheterization is a less invasive method of extracting urine from the bladder in dogs and is an excellent choice when a voluntary sample is unavailable, particularly in male dogs. A very narrow sterile catheter is inserted into the bladder through the lower urinary passage (called the urethra).
Mid-stream Free Flow: The pet urinates voluntarily, and a sample is collected into a sterile container as the pet urinates. This type of sample is frequently referred to as a "free flow" or "free catch" sample. The benefits of this method include the fact that it is completely non-invasive and that the pet owner can collect a urine sample at home.
Understanding the Results of a Urinalysis
There are four main parts to a urinalysis:
- Assess appearance: color and turbidity (cloudiness).
- Measure the concentration (also known as the density) of the urine.
- Measure pH (acidity) and analyze the chemical composition of the urine.
- Examine the cells and solid material (urine sediment) present in the urine using a microscope.
It is important to analyze urine samples within 30 minutes of collection to ensure the accuracy of the results. This is because various factors, such as crystals, bacteria, and cells, can potentially affect the composition of the urine by dissolving or multiplying. Please return the urine sample to your veterinary clinic as soon as possible if you collect it at home. The timing of urine collection is usually insignificant, unless we are evaluating your pet's ability to concentrate urine or screening for Cushing's disease. For screening Cushing's disease or assessing your pet's urine concentration, a urine sample is required in the morning.
Color & Turbidity
The color of urine can vary from pale yellow to light amber, and it may appear clear or slightly cloudy. Typically, dark yellow urine is a sign that the pet should increase their water intake or may be experiencing dehydration. If your urine is not yellow, such as orange, red, brown, or black, it could be a sign of substances in your urine that are not typically present in healthy urine. This may suggest an underlying health issue.
Cells or other solid materials in the urine cause an increase in turbidity or cloudiness. Presence of blood, inflammatory cells, crystals, mucus, or debris leads to an increase in turbidity. We will examine the sediment to determine its contents and assess its significance.
Think of urine density as a measure of concentration. Dogs and cats with dilute urine may be showing signs of underlying disease, while a healthy kidney produces concentrated urine.
The kidneys eliminate excess water from the body by allowing it to pass out through urine, resulting in a more watery or dilute urine. When water is scarce, the kidneys conserve water by reducing the amount lost in urine, resulting in a more concentrated urine.
Passing dilute urine from time to time in dogs or cats is usually not a cause for concern. If a pet is consistently passing dilute urine, it could indicate an underlying kidney or metabolic disease that needs to be investigated further.
pH & Chemical Composition
Urine acidity is indicated by the pH level. Healthy pets typically have a pH level in their urine that falls within the range of 6.5 to 7.0. Bacteria thrive in environments with either acidic (pH less than 6) or alkaline (pH greater than 7) conditions, leading to the formation of crystals or stones. Urine can vary throughout the day due to the consumption of certain foods and medications. A single urine pH reading is not a cause for concern if the rest of the urinalysis is normal. If the abnormality persists, your veterinarian may want to investigate it further.
Cells & Solid Material (Urine Sediment)
Some of the cells present in the urine can include:
Protein: Protein should not be found in urine on a dipstick test. A positive protein in urine test may indicate a bacterial infection, kidney disease, or blood in the urine.
Sugar: Urine should not contain any sugar. The presence of sugar in the urine may signal the presence of Diabetes mellitus.
Ketones: If your pet tests positive for ketones in its urine, a Diabetes Mellitus workup will be performed. Ketones are abnormal byproducts that your pet's cells produce when they lack an adequate energy source.
Bilirubin: Bilirubinuria is an abnormal finding that indicates that red blood cells in your pet's bloodstream are being destroyed at a faster than normal rate. It has been found in pets suffering from liver disease and autoimmune diseases. Remember that pets with blood in their urine due to a bladder infection can falsely stain the bilirubin pad on the dipstick, raising the possibility of a more serious liver problem.
Urobilinogen: Urobilinogen in urine indicates that the bile duct is open and bile can flow from the gallbladder into the intestine.
Blood: Blood in a dog's or cat's urine can indicate an infection, an inflammatory problem, or stones in the bladder or kidney. The dipstick can detect red blood cells or other blood components, such as hemoglobin or myoglobin, in your pet's urine.
Urine Sediment: This should also be examined when conducting a urinalysis. Urine sediment is the material that settles to the bottom of a centrifuge after spinning a urine sample. Red blood cells, white blood cells, and crystals are the most common things found in urine sediment. Small amounts of mucus and other debris are frequently found in free-catch samples.
Red Blood Cells: Red blood cells may indicate bladder wall or kidney trauma or irritation. In pets with bladder or kidney infections, bladder stones, or interstitial cystitis, the technician will find red blood cells in the urine. It may also be an early sign of cancer of the urinary tract.
White Blood Cells: White blood cells could indicate an infection or an inflammatory process in the bladder or kidney.
Crystals: There are numerous types of crystals that vary in size, shape, and color. Some crystals are one-of-a-kind and can aid in the diagnosis of a specific condition. In more common conditions, such as bladder infections, the crystals provide data that can influence how the disease is treated. Because crystals can form in urine after it has been collected, your veterinarian may want to examine a fresh sample right away.
Bacteria: The presence of bacteria as well as inflammatory cells in the sediment suggests that there is a bacterial infection somewhere in the urinary system. The urine should ideally be sent to a laboratory for culture and sensitivity testing to determine what types of bacteria are present and which antibiotic should be used to treat the infection.
Tissue Cells: Increased cellularity has been linked to several conditions, including urinary tract inflammation, bladder stones, prostate issues, and cancer. Catheterization samples frequently contain an increased number of tissue cells. If the cells appear abnormal, your veterinarian may advise you to have the sediment cytologically prepared. This allows for a more in-depth examination of the tissue cells.