Why Does My Pet Need a Urinalysis?

At Oakwood Animal Hospital, we treat our client's pets as our own. In this article, our vets discuss urinalysis for dogs and cats, as well as how to make the best decisions regarding their medical care.

Urinalysis: What Is It?

A urinalysis is a quick diagnostic test that determines the physical and chemical properties of urine. It is used to evaluate the health of an animal's 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 urinalysis every year. A urinalysis may also be recommended if your pet has increased water intake, increased frequency of urination, or they have blood in their urine.

How Does Urine Get Collected From Pets?

There are three ways to collect urine from cats and dogs:

Cystocentesis: Urine is collected from bladders using a sterile needle and syringe. During this process, 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. Keep in mind this procedure is 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. This is an excellent choice when a voluntary sample is unavailable, particularly in male dogs. The procedure uses a very narrow sterile catheter, that is inserted into the bladder through the lower urinary passage.

Mid-stream Free Flow: A sample is collected from a voluntary urination directly into a sterile container. 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 Urinalysis Results

There are four parts to a urinalysis:

1. Assess appearance: color and cloudiness.
2. Measure the concentration/ density of the urine.
3. Measure pH and analyze the chemical composition of the urine to understand the acidity.
4. Examine the cells and sediment present in the urine using a microscope.

Urine samples should be read within 30 minutes of the collection because crystals, bacteria, and cells can alter the composition. 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 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 orange, red, brown, or black 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 is also examined to determine what is present and whether it is significant.

Concentration

Concentration refers to the density of urine. A healthy kidney produces dense (concentrated) urine, whereas watery urine in dogs and cats may indicate an 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.

Occasional dilute urine in dogs is not a cause for concern. However, If a pet continuously passes dilute urine, there may be an underlying kidney or metabolic disease that requires further investigation.

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 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 the urine can include:

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.

Sugar: Urine should not contain any sugar. The presence of sugar in the urine may signal the presence of Diabetes mellitus.

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. 

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.

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.

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.