What is urinalysis for pets?
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.
Why would your pet need a urinalysis?
By performing a urinalysis in the veterinary diagnostics lab, your vet can gain valuable insight into the health and function of your pet's body and organs. Some of the concerns that a urinalysis can help detect and monitor include:
Urinary Tract Infection: Did you know that both dogs and cats are able to get urinary tract infections (UTI)? If bacteria or white blood cells are present in the sample then it means that there is an infection present. A urinalysis is usually requested in the case of cats and dogs that are urinating indoors to determine whether there is a behavioral issue or a medical concern. If the cause is determined to be a UTI the vet will prescribe antibiotics from the veterinary pharmacy to help treat the infection.
Urinary Crystals/Stones: It can be very painful if your cat or dog suffers from crystals in their urine. But that is not the only concern. Crystals can also increase the risk of UTIs and clump together to cause urinary stones. Typical treatment for standard cases includes antibiotics as well as a change in diet to alter the pH of your pet's urine and ultimately dissolve the crystals. These can also be diagnosed with the help of an ultrasound or X-ray and serious cases may require surgical removal of the crystals.
Kidney Disease: The main function of your pet's kidneys is to excrete urine. When your vet performs a urinalysis on your cat or dog they may use a refractometer to measure the density of their urine. This can show whether or not the kidneys are functioning as they should be. Your vet may then use blood tests to confirm this concern then recommend changes to diet and prescribe medications from the vet pharmacy to help manage the symptoms.
Diabetes: If your cat or dog is suffering from diabetes the vet may note excess glucose in their urine sample during urinalysis. Some pets may also have ketones present in their urine if they have diabetes. The ketones in the bodies of diabetic cats and dogs can be attributed to the breakdown of fats.
Urinary Tract Cancer: Certain tumors can be noted due to the presence of epithelial cells on a urinalysis. In this instance, your vet will utilize imaging equipment in the veterinary laboratory to diagnose the tumor.
Liver Disease: When the liver breaks down red blood cells it creates a byproduct known as bilirubin. While it is not out of the ordinary to see minimal amounts of bilirubin in your dog's urine but any excess amount should be investigated as this likely indicates an issue. If any bilirubin is noted in your cat's urine sample your vet will need to investigate immediately as this is unusual for cats.
What is the process for the collection of urine?
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 urine samples at home.
What do the results of the urinalysis mean?
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 read within 30 minutes of the collection because other factors (such as crystals, bacteria, and cells) can alter the composition (dissolve or multiply). If you collect a urine sample at home, please return it as soon as possible to your veterinary clinic. Unless we are evaluating your pet's ability to concentrate urine, or screening for Cushing's disease, the actual timing of urine collection is usually insignificant. But if we are screening for Cushing's disease or evaluating your pet's ability to concentrate urine, we want a urine sample taken first thing in the morning.
Color & Turbidity
Urine that ranges from pale yellow to light amber in color 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 could indicate an underlying health issue.
Increased turbidity or cloudiness in the urine indicates the presence of cells or other solid materials. Turbidity increases 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.
Concentration or Density
The concentration of the urine can otherwise be thought of as the density. A healthy kidney produces dense (concentrated) urine, whereas watery (dilute) urine in dogs and cats may indicate underlying disease.
If there is an excess of water in the body, the kidneys allow it to pass out in the urine, making the urine more watery or dilute. If water is deficient, the kidneys reduce the amount of water lost in the urine, making it 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 using the vet lab.
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 caused concern. If your pet is showing consistent abnormal readings then your vet will likely recommend further testing using the veterinary laboratory.
What do we learn from the cells present in the urine?
Some of the commonly seen cells found in urine might include:
Protein: Your vet should not note any protein when they perform 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. If your vet finds sugar in your pet's urine it could indicate that your pet has developed 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. This can also be caused by an infection which may also indicate a more serious issue.
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.
What about the sediment that appears during the urinalysis?
Some of the forms of sediment that may be present in the urine sample include:
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 is also possible for red blood cells to be an indicator of cancer which should be investigated further.
White Blood Cells: White blood cells could indicate an infection or an inflammatory process in the bladder or kidney. Your vet will recommend further testing utilizing equipment in the pet laboratory.
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 veterinary diagnostics lab 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.