At Montecito Veterinary Center, we believe in educating our clients so they can be the best pet owners possible. In this article, our Santa Rosa vets discuss urinalysis for dogs and cats, as well as how to understand urinalysis results.
What is a Urinalysis?
A urinalysis is a quick diagnostic test that determines the physical and chemical properties of urine. Urinalysis primarily assesses kidney and urinary system health but can detect issues in other organs. Pets aged eight and above should have an annual urinalysis. It's also recommended if your pet shows increased water intake, frequent urination, or visible blood in the urine.
How is Urine Collected?
Cystocentesis, Mid-stream free flow and Catheterization are the three main ways to collect urine from cats and dogs.
Cystocentesis: Urine is collected from the bladder using a sterile needle and syringe. The benefit of cystocentesis is that the urine is not contaminated by debris from the lower urinary tract. This sample is ideal for evaluating the bladder and kidneys as well as detecting bacterial infection. The procedure is slightly more invasive than others and is only useful if the pet's bladder is full.
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 the urine sample at home.
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).
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.
Urine samples should be examined within 30 minutes of collection to prevent changes in composition caused by factors like crystals, bacteria, and cells. If you collect a urine sample at home, please return it promptly to your veterinary clinic. The timing of urine collection is generally unimportant unless we are specifically testing for the ability to concentrate urine or screening for Cushing's disease. In such cases, a urine sample taken in the morning is preferred.
Turbidity & Color
Healthy urine typically ranges from pale yellow to light amber in color and appears clear to slightly cloudy. Dark yellow urine suggests the need for increased water intake or dehydration in the pet. Unusual colors such as orange, red, brown, or black may indicate the presence of substances not typically found in healthy urine, pointing to an underlying health issue.
Turbidity or increased cloudiness in urine indicates the presence of solid materials like cells or other particles. It is typically caused by factors such as blood, inflammatory cells, crystals, mucus, or debris. The sediment present in the urine will be examined to determine its composition and significance.
Healthy kidneys produce dense (concentrated) urine, while dilute urine in dogs and cats can indicate underlying disease.
When there is an excess of water in the body, the kidneys allow it to be eliminated in the urine, resulting in more watery or dilute urine. Conversely, if water is insufficient, the kidneys conserve water in the urine, leading to more concentrated urine.
Occasional passage of dilute urine in a dog or cat is generally not worrisome. However, if a pet consistently produces dilute urine, it may suggest an underlying kidney or metabolic disease that requires further investigation.
pH & Chemical Composition
The urine's pH level reflects its acidity. In healthy pets, the urine pH typically falls between 6.5 and 7.0. Deviations from this range, such as acidic pH (below 6) or alkaline pH (above 7), can promote bacterial growth and the formation of crystals or stones.
Normal variations in urine pH can occur throughout the day, particularly in response to specific foods and medications. If the rest of the urinalysis appears normal, a single abnormal urine pH reading is generally not a cause for concern. However, if the pH consistently deviates from the normal range, your veterinarian may recommend further investigation.
Some of the cells present in the urine can include:
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.
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.
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.
Tissue Cells: While not necessarily a sign of disease, 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 enables a more in-depth examination of the tissue cells.
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.
Urine sediment: Urine sediment 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.