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Urinalysis is a diagnostic tool that can provide insights into a horse’s overall health. By examining the appearance and composition of urine, veterinarians can assess kidney function, hydration status, and the presence of certain toxins. Although urinalysis is not used as often as bloodwork or imaging, it plays an important part of a complete diagnostic workup.
A standard urinalysis evaluates physical traits such as color, clarity, and odor, as well as chemical properties like pH, and the presence of protein, glucose, and blood in the urine. A urinalysis can also involve examining cells, crystals, and other sediment under the microscope.
These findings can help veterinarians detect conditions such as urinary tract infections, bladder stones, kidney disease, and systemic illnesses such as metabolic disorders. Whether your horse is showing obvious urinary symptoms or experiencing vague changes such as weight loss or poor performance, a urine test can guide treatment and management.
Read on to learn everything you need to know about the basics of urinalysis in horses, how samples are collected, what results mean, and when this test is most beneficial for your horse.
Urinalysis for Horses
Urinalysis is the process of examining urine in a laboratory setting. This procedure allows veterinarians to identify abnormalities that may indicate disease processes occurring in the horse’s body.
Although more commonly performed in dogs and cats where sample collection is simple, urinalysis can also provide important insights in horses.
Veterinarians can obtain an equine urine sample by passing a catheter into the bladder, or waiting until the horse urinates on their own. Catheterization is often preferred as it can be performed any time.
Common reasons a veterinarian may perform urinalysis include: [1]
- Diagnosing acute or chronic kidney disease
- Identifying urinary crystals contributing to urolithiasis
- Evaluating the severity of dehydration
- Identifying muscle proteins in the urine, indicating muscle damage
- Evaluating electrolyte loss in the urine to diagnose the cause of renal dysfunction
When to Use Urinalysis in a Horse?
Signs that indicate a horse may need a urinalysis as part of a diagnostic workup include: [2]
- Abnormal urine color
- Weight loss
- Lethargy
- Changes in urination frequency
- Changes in urine volume
- Increased thirst
- Urinary incontinence or evidence of urine scalding
- Inability to urinate
- Pain during urination
- Fever
- Poor performance
Equipment
Most veterinarians prefer to catheterize a horse to collect a urine sample. Not only does this limit the waiting time before a sample is gathered, it also reduces sample contamination by bacteria, dirt, and other foreign objects on the horse’s skin.
Male and female horses require a slightly different set of equipment and procedure, as males have a much longer urethra. For male horses, veterinarians use a long “stallion catheter” that is 150 cm (60 in) in length. For mares, smaller catheters up to 40 cm (16 in) are preferred. [3]
Other equipment includes: [3]
- Soap to clean the skin around the penis or vulva
- A large syringe
- A sterile specimen cup to store the collected urine
- Lubricant
Most horses require restraint during the procedure for the safety of their handlers and the veterinarian. For male horses, many veterinarians sedate the horse to reduce their movement. They may also have a handler apply a twitch to provide a distraction. [3]
This is particularly important as the catheterization process in males requires the veterinary team to be “under” the horse to access the urethra.
“Urinalysis gives us valuable information that might not appear on bloodwork. By looking at the color, concentration, and chemistry of a horse's urine, we can detect early signs of kidney disease, metabolic disorders, or urinary tract infections.”
— Dr. Jennifer Skaggs, DVMEquine Veterinarian
Docile mares, particularly those who are used to frequent palpation or other reproductive procedures, often do not require sedation when collecting a urine sample. [3] In this case, the veterinarian places the mare in stocks for restraint and to reduce the risk of getting kicked. [3] If the mare is more spirited, they may choose to sedate them for the procedure.
Once urine is collected, the veterinary team processes the sample using dipstick tests and a refractometer, a piece of equipment that uses light to measure the concentration of urine. They also evaluate a sample of urine under a microscope. [4]
What's your top priority with your horse's health?
Procedure
The catheterization process differs slightly between male and female horses.
Male Horses
The veterinarian sedates the horse and allows time for the sedation to come into full effect. They may then ask the handlers to restrain the horse further, such as by putting them in stocks or applying a twitch. [3]
An assistant firmly grasps the horse’s penis to prevent them from retracting it into their sheath. The assistant and veterinarian clean the penis to prevent transfer of bacteria on the skin into the bladder while passing the urinary catheter. [3]
Once prepared, the veterinarian puts on sterile gloves and lubricates the catheter. They pass the catheter into the horse’s urethra until it reaches the bladder.
Once the catheter is seated in the bladder, urine typically flows out freely. If it does not, the veterinarian attaches the syringe and uses it to gently aspirate a urine sample. The assistant collects the urine in a specimen cup for further processing. The veterinarian then removes the catheter carefully. [3]
Female Horses
Catheterization in mares begins by wrapping the tail and thoroughly cleaning the vulva. Many veterinarians also disinfect the vulvar skin with surgical scrub, such as chlorhexidine. Once the mare is clean, they put on sterile gloves and lubricate the catheter. [3]
The catheter is introduced into the vulva and guided down into the urethra by the veterinarian’s hand. Once the catheter reaches the bladder, an assistant attaches a syringe and aspirates a urine sample. [3]
Laboratory Analysis
The most common laboratory analyses performed on urine are visual examination, reagent strip analysis (dipstick analysis), cytology, and refractometry. [4] The veterinary team also examines the overall color, clarity, and odor of the urine.
Visual Examination
Healthy equine urine is yellow, cloudy, and has a slight ammonia odor. [5] Some conditions can cause the urine’s color to change, such as muscle disorders. Protein, crystals, blood, or white blood cells in the urine can alter its clarity. Finally, bacterial infections can increase the ammonia odor of urine in some cases. [5]
Dipstick Analysis
Dipsticks are specialized strips of paper with chemical pads that detect specific compounds in a liquid sample. By soaking these pads in urine, the veterinary team can assess for compounds such as blood, ketones, bilirubin, and glucose. [4]
Cytology
Cytology involves looking at the urine sample under the microscope. A member of the veterinary team places a drop of urine on a slide, then examines it. Through this assessment, they can identify urinary crystals, white blood cells, red blood cells, and urinary casts. [5]
Refractometry
Refractometry is the preferred method of assessing urine specific gravity, or the concentration of urine. [4] The veterinarian places a drop of urine on a refractometer and holds it up to the light. Depending on the degree of refraction (bending of light) that the urine has, it gives an estimate of the urine’s specific gravity. [4]
Interpreting Results
The results of laboratory analysis can provide the veterinary team with clues about what disease process may be occurring in your horse. Some common findings are described below.
Changes in Urine Specific Gravity
Urine specific gravity is the concentration of the urine. This value fluctuates based on the horse’s hydration level and kidney function. [5] Excess water intake leads to hyposthenuria, or very low urine specific gravity. [4]
Dehydration typically leads to hypersthenuria, highly concentrated urine. Horses with kidney disease may lose their ability to alter urine concentration. These horses develop isosthenuria, which is where their urine concentration is the same as their blood concentration. [4]
Proteinuria
Proteinuria refers to protein in the urine. This is an abnormal condition indicating that the kidneys are unable to remove excess protein from the urine. This can occur due to excess protein release into the bloodstream, kidney failure preventing normal kidney function, or inflammation and infection of the urinary tract. [4]
Glucosuria
Glucosuria refers to glucose (sugar) in the urine. Healthy kidneys remove glucose from the urine, preventing loss of this valuable energy source. Horses with hyperglycemia (high blood sugar) may develop glucosuria when the kidneys are unable to keep up with the amount of glucose lost in the urine. This can indicate insulin resistance in horses. [4]
Urinary Crystals
Urinary crystals identified under the microscope can indicate urolithiasis, or urinary stones. Small amounts of urinary crystals are normal in horses, but large quantities may indicate the potential for urinary stone development. [4]
Urinary Casts
Urinary casts are clusters of protein in the shape of a tube, visible under the microscope. They indicate that the renal tubules, the tube-like structures that make up the kidney, are damaged. [4]
Pyuria
Pyuria refers to white blood cells in the urine. This typically indicates that there is an inflammatory or infectious process occurring within the urinary tract. [4]
Although dipsticks often include chemicals for detecting white blood cells, equine veterinarians usually prefer to count these cells under the microscope for accuracy as the dipstick test can give false results. [4]
Hematuria
Hematuria means that there are whole red blood cells in the urine. This can occur due to traumatic injury, kidney infections, tumors, urolithiasis, and other conditions. [4]
Myoglobinuria
Myoglobin is a muscle protein that is released when muscle damage occurs. The kidneys release this red-brown protein into the urine, causing discoloration. [4]
Hemoglobinuria
Similar to myoglobin, hemoglobin is a red-brown protein found within red blood cells. If there is excessive destruction of red blood cells in the body, hemoglobin is released into the urine. [4] Hemoglobinuria can indicate severe diseases, such as hemolytic anemia.
Fractional Excretion
Fractional excretion is a test where the amount of different electrolytes in the bloodstream is compared to the amount present in the urine. It is primarily used for evaluating renal dysfunction. [4]
Preparing Your Horse for Urinalysis
There are no specific steps you must take to prepare your horse for urinalysis.
Work with your veterinarian to determine what restraint protocol is most appropriate for your horse based on their temperament and level of training.
Complications
Urinary catheterization is a safe procedure with few complications. One study evaluating complications in urinary catheters during recovery from surgery showed that only 1.4% of horses developed complications. [6]
Possible complications include traumatic injury to the urinary tract and bladder infections. [3][6] Minor traumatic injuries typically resolve on their own without further intervention, however a stricture (tight band of scar tissue) may develop at the damaged site. [6]
Improper sterilization of the skin surrounding the urethra may allow bacteria to contaminate the catheter and enter the bladder. Veterinarians treat these cases using antibiotics that pass into the urine, allowing for targeted treatment of the urinary system.
Frequently Asked Questions
Here are some frequently asked questions about urinalysis in horses:
Urinalysis is a diagnostic test that examines a horse's urine for information about kidney function, hydration status, and possible health issues. It typically includes evaluating urine color, odor, clarity, specific gravity, pH, and the presence of substances such as protein, glucose, blood, or crystals.
A urinalysis may be recommended if your horse shows signs of urinary problems (such as frequent urination, straining, or abnormal urine color), unexplained weight loss, poor performance, dehydration, or systemic illness. It is also used to monitor kidney and urinary tract health in horses with known conditions.
Urine can be collected from horses in two ways: free-catch (collecting mid-stream as the horse urinates) or catheterization (inserting a sterile tube into the bladder).
Urinalysis can provide information about your horse's hydration, kidney function, and metabolic health. Abnormal findings, such as the presence of blood, protein, sugar, or unusual crystals, may point to conditions like urinary tract infections, bladder stones, kidney disease, or metabolic disorders.
No special preparation is usually required for urinalysis in horses.
Summary
Urinalysis in horses is the process of evaluating a urine sample to diagnose conditions affecting the horse's body.
- Urinalysis is an important component of diagnostic workups where dysfunction of the urinary tract is suspected
- A standard urinalysis includes evaluating the urine's visual appearance, a dipstick test, refractometry, and cytology
- Veterinarians primarily use urinalysis for diagnosing kidney disease, however it can also diagnose other conditions
- Most veterinarians prefer urinary catheterization to collect a urine sample
References
- Savage. C. J. Urinary Clinical Pathologic Findings and Glomerular Filtration Rate in the Horse. Veterinary Clinics of North America: Equine Practice. 2008.
- Schott. H. C. Chronic Renal Failure in Horses. Veterinary Clinics of North America: Equine Practice. 2007.
- Costa. L. R. R. and Paradis. M. R. Manual of Clinical Procedures in the Horse. Wiley Blackwell, Hoboken. 2018.
- Gratwick. Z. An Updated Review: Laboratory Investigation of Equine Renal Disease. Equine Veterinary Education. 2021.
- Whitbread. T. et al. Urinalysis - Clinical Pathology and Procedures. Merck Veterinary Manual. 2025.
- Quinn. C. Incidence of Complications from Perioperative Urinary Catheterisation in Horses. Australian Veterinary Journal. 2025.
