A urinalysis can help your vet detect whether your cat or dog is suffering from an illness or health problem requiring treatment. Our vets in San Mateo explain why it's important for pets to undergo regular urinalysis.
Urinalysis for Pets
A simple diagnostic test called a urinalysis determines your pet's urine's physical and chemical properties. While our specialty and emergency veterinarians most often use urinalysis to assess the health of a cat or dog's urinary system and kidneys, it can also reveal problems with other organ systems.
All senior pets aged eight years and over should have a urinalysis every year. Your veterinarian may also recommend a urinalysis if your pet drinks more water, urates more frequently than usual, or if blood is visible in the urine.
Collecting a Urine Sample
There are three main methods of collecting urine from cats and dogs:
Mid-Stream Free Flow: The sample is collected into a sterile container while your pet urinates voluntarily. Frequently referred to as a "free catch" or "free flow" sample, this method is completely non-invasive and allows the pet owner to collect a urine sample at home.
Cystocentesis: A sterile needle and syringe are used to collect urine from the bladder. The advantage of cystocentesis is that the urine will not be contaminated by debris from the lower urinary tract. This sample is ideal to help your veterinarian evaluate the bladder and kidneys. It can also be used to detect bacterial infection. This procedure is a little more invasive than the others and should only be performed if the animal's bladder is full.
Catheterization: This is a less invasive method of extracting urine from a dog's bladder and is an excellent option when a voluntary sample is unavailable, especially in male dogs. A very narrow sterile catheter will be inserted into the bladder through the lower urinary passage (urethra).
Understanding the Results of a Urinalysis
A urinalysis has four main elements:
- Assess the appearance of the urine, including its color and turbidity (cloudiness).
- Measure the concentration (also known as density) of the urine.
- Measure pH (acidity) and analyze the urine's chemical composition.
- Examine the cells and solid material (urine sediment) in the urine using a microscope.
Urine samples should be analyzed within 30 minutes of collection, as other factors (such as bacteria, cells, and crystals) can alter their composition (by causing them to dissolve or multiply).
If you collect a urine sample at home, please return it to our veterinary hospital immediately. Unless we're assessing your pet's ability to concentrate urine or testing for Cushing's disease, the timing of urine collection is not important. If we are testing for Cushing's disease or assessing your pet's ability to concentrate urine, it's ideal to collect a urine sample first thing in the morning.
Color & Turbidity
Pale yellow or light amber urine, clear or slightly cloudy, is healthy. Dark yellow urine usually indicates that your pet needs to drink more water or is dehydrated. Urine that is not yellow (e.g., orange, brown, red, or black) may contain substances not normally present in healthy urine and may indicate an underlying health problem.
Increased turbidity or cloudiness in your pet's urine indicates the presence of cells or other solid matter. Turbidity increases in the presence of inflammatory cells, crystals, blood, debris or mucus. The sediment will be examined to determine which of these elements are present and if they are significant.
Concentration
Concentration refers to urine density. If your pet's kidneys are healthy, they will produce dense (concentrated) urine, whereas dilute or watery urine in cats and dogs can be a symptom of an underlying disease.
If there's too much water in the body, the kidneys let it pass into the urine, making it more watery or dilute. If there's not enough water in the body, the kidneys reduce the amount of water lost in the urine, making it more concentrated.
A cat or dog whose urine is diluted occasionally is not necessarily a cause for concern. On the other hand, if the animal continually emits dilute urine, this may indicate an underlying metabolic or renal disease that requires further investigation and management.
pH & Chemical Composition
The pH level of the urine indicates its acidity. The pH of urine in healthy pets is usually between 6.5 and 7.0. If the pH is acidic (pH less than 6) or alkaline (pH greater than 7), bacteria can thrive and crystals or stones can form.
Normal variations in urine occur throughout the day, especially when certain foods and medications are consumed. If the rest of the urinalysis is normal, a single urine pH reading is not a cause for concern. If it is consistently abnormal, your veterinarian may wish to investigate further.
Cells & Solid Material (Urine Sediment)
Some of the cells present in your pet's urine can include:
Red Blood Cells: Red blood cells may indicate bladder wall or kidney trauma or irritation. The technician will find red blood cells in pets' urine with bladder or kidney infections, bladder stones, or interstitial cystitis. 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.
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 indicating that red blood cells in your pet's bloodstream are being destroyed faster than normal. 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.
Crystals: Numerous types of crystals vary in size, shape, and color. Some crystals are unique and can aid in diagnosing 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 being collected, your veterinarian may want to examine a fresh sample immediately.
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: 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.
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.