By testing your cat or dog's urine your vet can diagnose health conditions and monitor various aspects related to the function of their body. Here, our vets in Los Angeles discuss the purpose of urinalysis for dogs and cats, how urine samples are collected and what we look for in each sample.
Urinalysis for Dogs & Cats
A urinalysis is a simple diagnostic test that assesses urine's physical and chemical properties. It is mainly used to evaluate the health of the kidneys and urinary system, but it can also detect issues with other organ systems. All senior pets aged eight years or older should undergo a yearly urinalysis. Moreover, a urinalysis may be recommended if your pet is drinking more water, urinating more frequently, or has visible blood in their urine.
How Urine Samples are Collected
There are three main ways to collect urine from cats and dogs:
Cystocentesis: A sterile needle and syringe are used to collect urine from a pet's bladder. The advantage of this method, called cystocentesis, is that it ensures the urine sample remains unadulterated by debris from the lower urinary tract. This type of sample is best suited for assessing the bladder and kidneys and detecting bacterial infections. However, this procedure is slightly more invasive than other methods and can only be performed when the pet's bladder is full.
Catheterization: Catheterization is a minimally invasive technique used to extract urine from the bladder of dogs. It is particularly useful when a voluntary sample is not available, especially in male dogs. The process involves inserting a narrow, sterile catheter into the bladder through the urethra, which is the lower urinary passage.
Mid-stream Free Flow: To collect a urine sample from a pet, a sterile container is held in place while the pet urinates voluntarily. This sample type is often called a 'free flow' or 'free catch' sample. The benefits of this method are that it is completely non-invasive and that pet owners can collect a urine sample at home.
What We Learn From Urinalysis for Dogs & Cats
There are four main components to a urinalysis for pets:
- 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.
Your vet will need to examine the sample within 30 minutes of collection. This is because various factors, such as crystals, bacteria, and cells, can alter the sample's composition. If you collect a urine sample at home, it should be done immediately before heading over to the clinic. The timing of urine collection is usually not significant unless we are testing your pet's urine concentration or screening for Cushing's disease. For these specific cases, collecting the urine sample first thing in the morning is best.
Color & Turbidity
The health status of your pet can be preliminarily indicated by the color of their urine. Normally, urine should be pale yellow to light amber, clear to slightly cloudy. However, if your pet's urine is dark yellow, that may indicate that they need to drink more water or they might be dehydrated. On the other hand, if the urine is not yellow but appears to be orange, red, brown, or black, it could mean that there are substances present in the urine that are not typically found in healthy urine, which may hint at an underlying medical condition.
Increased turbidity or cloudiness in the urine indicates the presence of cells or other solid materials. Turbidity increases when blood, inflammatory cells, crystals, mucus, or debris are present. Your vet will examine the urine sediment to get a better idea of what is happening to your pet internally.
Concentration of Urine
When we talk about the concentration of the urine we are referring to the density. A healthy kidney produces dense or concentrated urine. On the other hand, watery or dilute urine in dogs or cats may indicate an underlying disease.
When there is excess water in the body, the kidneys allow it to pass out in the urine, making it more watery or dilute. Conversely, when water is deficient, the kidneys reduce the amount of water lost in the urine, resulting in more concentrated urine.
If a pet occasionally passes dilute urine, it may not necessarily be a cause for concern. However, if your pet consistently passes dilute urine, it could indicate an underlying kidney or metabolic disease. Therefore, it's best to consult a veterinarian for 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 a cause for concern. If it is consistently abnormal, your veterinarian may wish to investigate further.
What we Learn from Cells & Solid Material (Urine Sediment)
When conducting a urinalysis, it is important to examine the urine sediment. Urine sediment refers to the material that settles at the bottom of a centrifuged urine sample. The most common things found in urine sediment are red blood cells, white blood cells, and crystals. Free-catch urine samples often contain small amounts of mucus and other debris.
Some of the cells present in your pet's urine can include:
Red Blood Cells: Your veterinarian may find red blood cells in the urine of pets 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: Your vet should not note protein when performing a dipstick test. A positive protein in urine test may indicate a bacterial infection, kidney disease, or blood in the urine.
Sugar: Like protein, sugar is another material that should not be found when testing the urine. 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 indicates that the 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: The dipstick can detect red blood cells or other blood components, such as hemoglobin or myoglobin, in your pet's urine. Blood in a dog's or cat's urine can indicate an infection, an inflammatory problem, or stones in the bladder or kidney.
Crystals: Crystals can vary in shape and size. 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.
Tissue Cells: The presence of bacteria and inflammatory cells in the urine sediment is a sign of a possible bacterial infection in the urinary system. It is best to send the urine sample to a laboratory for culture and sensitivity testing to determine the specific type of bacteria present and the most effective antibiotic treatment.
Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding people or pets. If you are concerned about your pet's health, contact your veterinarian right away for diagnosis and treatment.