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Protein Losing Nephropathy in Dogs and Cats: Signs, Treatment, and What to Expect

Golden Retriever named Benny who has PLN and IBD.

What Is Protein Losing Nephropathy in Dogs and Cats?

Protein losing nephropathy (PLN) is a condition where the kidneys lose protein into the urine. This happens when the kidney filters (called glomeruli) become damaged.

Normally, these filters keep protein in the body. With PLN, protein leaks out. This loss can harm the kidneys and the rest of the body over time.

PLN is not one single disease. It is a group of conditions that affect how the kidneys work. Some cases may involve immune-related or infectious causes, while others do not.

As PLN progresses, many pets also develop high blood pressure. This can further damage the kidneys if not treated.

Signs of Protein Losing Nephropathy

Many pets with PLN show few signs early on. As the condition worsens, you may notice changes like:

Early and Common Signs

  • Weight loss
  • Decreased appetite
  • Lethargy
  • Swelling in the legs or abdomen
  • Increased thirst or urination

Serious Complications

  • Blood clots
  • Fluid in the chest (trouble breathing)
  • Progressive kidney failure

If your pet shows trouble breathing, weakness, or collapse, seek veterinary care right away.

How Veterinarians Diagnose PLN

Your veterinarian will use a combination of tests to diagnose PLN. These may include:

Diagnostic Testing

  • Urine protein-to-creatinine ratio (UPC)
  • Urine Culture
  • Bloodwork (kidney values, proteins, electrolytes)
  • Blood pressure measurement
  • Infectious disease testing (if needed)

Some pets may need additional testing if there is concern for underlying causes.

Treatment for Protein Losing Nephropathy

Treatment focuses on slowing disease progression and protecting your pet’s quality of life. Because PLN is complex, treatment should always be guided by a veterinarian.

Most pets require a combination of diet, medications, and regular monitoring. Your veterinarian will tailor this plan to your pet’s specific condition.

Kidney Diets

Veterinarians often prescribe therapeutic kidney diets that are:

  • Low in protein
  • Low in phosphorus
  • High in omega-3 fatty acids

These diets reduce the workload on the kidneys. While you may not see immediate improvement, they play a critical role in slowing disease progression.

Because these diets can vary, your veterinarian will help you choose the right option for your pet.

Omega-3 Fatty Acids

Omega-3 fatty acids can help reduce inflammation in the kidneys.

Only use supplements recommended by your veterinarian, as dosing and product quality can vary widely.

Medications to Reduce Complications

Pets with PLN are at risk for serious complications, including blood clots and high blood pressure.

Your veterinarian may prescribe medications such as:

  • Anti-clotting medications
  • Blood pressure medications

These medications require careful dosing and monitoring. They should never be started without veterinary guidance.

Monitoring and Long-Term Care

PLN is a complex condition, but with veterinary guidance, many pets can be managed successfully and maintain a good quality of life. It requires ongoing monitoring and follow-up care.

Regular Rechecks

Your veterinarian will recommend:

  • Blood pressure checks
  • Bloodwork
  • Urine testing
  • Urine cultures to screen for infection

Most pets need rechecks every 3–6 months once stable.

Risk of Urinary Tract Infections

Pets with PLN are more prone to infections, even without symptoms. Routine urine cultures help detect these early.

Prognosis: What to Expect

PLN will worsen over time, but early and consistent care can slow progression.

There are three main ways PLN may progress:

1. Kidney Failure

Gradual decline in kidney function over time.

2. Blood Clots

Can cause sudden, life-threatening complications.

3. Nephrotic Syndrome

Severe protein loss leads to fluid buildup, including around the lungs.

While progression is expected, proactive care can help maintain quality of life for as long as possible.

When to See a Veterinary Internal Medicine Specialist

Your primary care veterinarian can manage many PLN cases. However, referral to a specialist may help when:

  • Diagnosis is unclear
  • The disease progresses quickly
  • Blood pressure is hard to control
  • Complications develop

Sunstone Veterinary Specialists offers advanced internal medicine care. If your veterinarian suspects PLN or refers you for further evaluation, our team can help guide diagnosis and treatment.

Learn More About Protein Losing Nephropathy

For more information, we recommend these trusted resources:

These provide both general and more detailed overviews for pet owners who want to learn more.

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