At Animal Care Extraordinaire, we believe strongly in educating our clients so they can be the best possible pet owners. So today, our Stuart 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: 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.
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 the 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.
Because other factors (such as crystals, bacteria, and cells) can change the composition (dissolve or multiply), urine samples should be read within 30 minutes of collection. If you collect a urine sample at home, please return it to your veterinary clinic as soon as possible. The actual timing of urine collection is usually insignificant unless we are evaluating your pet's ability to concentrate urine or screening for Cushing's disease. However, if we are testing for Cushing's disease or assessing your pet's ability to concentrate urine, we will need a urine sample first thing in the morning.
Color & Turbidity
Urine that ranges in color from pale yellow to light amber and is clear to slightly cloudy. Dark yellow urine usually indicates that the pet needs to drink more water or is dehydrated. Urine that is not yellow (for example, orange, red, brown, or black) may contain substances that are not normally found in healthy urine and may indicate an underlying health problem.
Increased turbidity or cloudiness in the urine indicates the presence of cells or other solid materials. Turbidity rises when there is blood, inflammatory cells, crystals, mucus, or debris present. The sediment will be examined to determine what is present and whether it is significant.
Consider concentration to be the density of the urine. A healthy kidney produces dense (concentrated) urine, whereas watery (dilute) urine in dogs and cats may indicate underlying disease.
When there is an excess of water in the body, the kidneys allow it to pass through the urine, making it more watery or dilute. When there is a lack of water, the kidneys reduce the amount of water lost in the urine, causing it to become more concentrated.
If a dog or cat passes dilute urine from time to time, it is not necessarily a cause for concern. If a pet continuously passes dilute urine, there may be an underlying kidney or metabolic disease that requires further investigation.
pH & Chemical Composition
The urine's pH level reveals how acidic it is. Healthy pets typically have urine with a pH of 6.5 to 7.0. Bacteria can flourish and crystals or stones can form in an acidic (pH less than 6) or alkaline (pH greater than 7) environment. Throughout the day, urine typically varies, especially after taking certain foods and medications. A single urine pH reading is unimportant if the rest of the urinalysis is normal. Your veterinarian might want to look into it further if it consistently behaves abnormally.
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 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 associated with a number of diseases, including cancer, bladder stones, prostate problems, and inflammation of the urinary tract, although it is not always a sign of disease. Samples taken during catheterization frequently have more tissue cells than usual. Your veterinarian might recommend having the sediment processed cytologically if the cells seem abnormal. This makes it possible to examine tissue cells more thoroughly.