Protein in Dog Urine: What Does It Mean?

Published on 10/24/2023

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Suppose your veterinarian told you they noted protein in your dog’s urine. What does that mean exactly? Does it mean there is a problem with your dog’s kidneys? And is protein in dog urine dangerous?

In this article, we will take an in-depth look at what causes protein in dog urine, the symptoms of too much protein in a dog’s urine, and what veterinarians recommend for treatment.

Protein in Dog Urine: What is it?

Typically, a healthy dog’s urine should have very little to no protein in it. Protein is a precious resource in a healthy body and must be conserved. When blood is filtered through the kidneys, the kidneys resorb protein, vitamins, and minerals back into the bloodstream. At the same time, these vital organs excrete metabolic by-products, toxins, and excess water into urine, to be eliminated from the body. If the kidneys aren’t working correctly or there is bleeding or inflammation anywhere in the urinary or reproductive tract, that can be picked up on a urine test as protein in the urine, also known as proteinuria in dogs.

A complete urinalysis is one of the most common laboratory tests run in veterinary hospitals. This is a dog urine test to check the health of the urinary system and other related body systems. A veterinarian may run this test during routine annual examinations or when a dog is sick. It is usually a paper strip dipped in urine and then evaluated for things like sugar in the urine, blood, infections, etc. The test also checks for protein in the urine.

If proteinuria is detected on the screening test, your veterinarian will examine the urine under a microscope for evidence of red blood cells or a urinary tract infection, which can falsely elevate protein readings on urinalysis dipstick tests.

Your veterinarian may also recommend a more specific test called a urine protein: creatinine ratio (UPC) to accurately determine how much protein is in your dog’s urine. Here is how UPC ratios are measured:

UPC less than 0.2 is considered normal
UPC between 0.2-0.5 is considered borderline proteinuria
UPC greater than 0.5 in dogs indicates that your dog has an abnormal amount of protein in their urine

These ratios can vary, and most veterinarians will repeat a UPC a few times over a few weeks to determine persistent proteinuria before moving on to more testing or treatment.

Causes of Protein in Dog Urine

There are many causes of proteinuria in dogs, and it isn’t always kidney disease. Proteinuria is grouped into three main categories: pre-renal (caused before the kidneys), renal (kidney in origin), and post-renal (caused after the kidneys).

Pre-renal causes of proteinuria in dogs include:

Hemolysis (widespread destruction of red blood cells)
Severe muscle injury
Cushing’s Syndrome
Fever
Heat stroke
Seizures
Strenuous exercise

In all these conditions, the kidney is overwhelmed by protein and filters excessive protein from the blood into the urine.

Renal (kidney) causes of proteinuria in dogs include kidney disease of any kind. Kidney disease impairs the kidney glomeruli, which are the thousands of mini-filtration apparatus in the kidney that filter the blood and make urine. This damage may be reversible if caught early but often creates permanent scarring. If the glomeruli are damaged, microscopic holes are punched in the filter, which lets protein escape into the urine.

Kidney disease in dogs can be caused by:

Bacterial infections
Parasitic infections, including heartworm
Cancer
Immune-mediated disease
High blood pressure
Cushing’s Syndrome
Pyometra
Chronic inflammation of any kind, including obesity

Post-renal causes of proteinuria in dogs include:

Lower urinary tract inflammation, such as is seen with urinary tract infections, cancer, or urinary stones

Inflammation in the lower urinary tract will be detected as protein on the urine test.

If your dog has proteinuria, it is considered abnormal, and it will be important to work with your veterinarian to determine the cause and eliminate it if possible.

Symptoms of Proteinuria in Dogs

Moderate to severe proteinuria can cause the following symptoms:

Weight loss
Decreased or increased appetite
Lethargy
Swollen paws or belly (edema)

Dogs that have proteinuria due to kidney disease often have the following symptoms:

Peeing a lot
Drinking a lot
Weight loss
Decreased appetite

If you notice any of the symptoms in either of the above lists, make an appointment to have your dog seen by a veterinarian as soon as possible.

Mild to moderate proteinuria does not usually cause clinical symptoms in dogs unless they have clinical signs associated with the underlying cause. For example, dogs with proteinuria due to a urinary tract infection may also have bloody urine, increased urge to urinate, and may be straining to urinate. These dogs need to be seen by a veterinarian.

Diagnosing the Cause of Excess Protein in Dog’s Urine

If your dog has had a confirmed diagnosis of elevated urine protein by multiple UPCs or if your dog is sick and has an elevated UPC, then it is time to run some additional tests to determine the cause of proteinuria. These tests can include:

Blood tests (complete blood count, serum chemistry, thyroid, tests for Cushing’s if suspected)
Imaging tests such as abdominal radiographs (X-rays) and/or abdominal ultrasound
Blood pressure monitoring
Urine culture and sensitivity
Kidney biopsy if urine proteinuria is thought to be kidney in origin

Protein in Dog Urine Treatment

Treatment of excess protein in dog urine varies depending on the underlying cause. For example, if the cause is pre-renal (fever, heat stroke, Cushing’s Syndrome, etc.), treatment focuses on fixing those issues. If the cause is post-renal (urinary tract inflammation), the treatment can be antibiotics for infections or surgery, or food therapy for urinary stones and crystals. Proteinuria should resolve once the underlying cause is identified and eliminated, and no further treatment should be necessary.

Proteinuria due to kidney disease has a range of treatments that may include:

ACE inhibitor medication to reduce proteinuria
Medication to lower blood pressure
Omega 3 fatty acids from high-quality fish oil (ask your vet for a dose)
Low-dose aspirin to prevent blood clots
Low protein therapeutic food formulated for pets with kidney disease

The prognosis for dogs with kidney disease varies. While it is usually not cured by treatment, there are reports of spontaneous remission. If your dog is diagnosed with kidney disease, it is important to work closely with a veterinarian you trust, follow their recommendations, and give medications as prescribed.

How to Prevent Protein in Dog Urine

Because mild to moderate proteinuria often has no accompanying symptoms, it can be helpful to have your dog’s urine tested each year by your veterinarian, as most diseases associated with proteinuria have a better prognosis if caught early.