If Your Cat Has Proteinuria — Causes of Glomerulonephritis and Timing of Treatment

KidneyDiseasesMeongsiljang Veterinary Advisory Board

Feline glomerulonephritis is a condition in which damage to the kidney's glomeruli allows protein to leak into the urine, making early detection crucial. While symptoms may not appear in the early stages, they can include swelling, changes in urination, and weight loss as the disease progresses.

What Is Feline Glomerulonephritis?

An image comparing healthy and damaged glomeruli in a cat's kidneys.

Feline glomerulonephritis is a condition in which damage to the kidney’s glomeruli allows protein to leak into the urine. Early stages often show few or no symptoms, making early detection difficult, but as the disease progresses, kidney function declines. This can lead to chronic kidney disease, so early diagnosis and management are crucial. The glomeruli play a vital role in filtering blood; when damaged, protein escapes from the body. If this persists, structural kidney damage worsens, and the prognosis varies significantly depending on the timing and approach to treatment. Therefore, regular check-ups are essential.

What Are the Main Causes of Glomerulonephritis?

Feline glomerulonephritis often occurs when immune complexes deposit on the glomerular filtration membrane, triggering an inflammatory response. This immune complex-mediated glomerulonephritis can arise primarily, but it may also develop secondary to infections (such as Lyme disease, leishmaniasis, ehrlichiosis, heartworm disease, FIV, FeLV, or FIP), autoimmune disorders (such as systemic lupus erythematosus or immune-mediated hemolytic anemia), or certain medications (such as NSAIDs). A non-immune complex form is renal amyloidosis, which is most commonly reported in Abyssinian and Siamese cats. However, since proteinuria can result from causes other than glomerular disease, accurately identifying the underlying cause is crucial for determining the appropriate treatment plan.

An image showing immune complex deposition in the glomeruli of a cat's kidneys.

What Are the Main Symptoms and Signs?

In the early stages of feline glomerulonephritis, symptoms are often minimal or absent. However, as proteinuria progresses, the following signs may appear:

Proteinuria: A condition where protein is present in the urine.

Edema: Fluid accumulation in areas such as the eyelids, abdomen, and legs.

Increased urination: A noticeable increase in the frequency of urination throughout the day.

Decreased appetite: Reduced food intake, often accompanied by weight loss.

Fatigue: Lethargy, with the cat resting more and showing less activity.

If you notice any of these symptoms, it is important to seek veterinary care immediately.

A photo showing a cat's leg with swelling.

Situations Requiring Immediate Veterinary Visit

If your cat has completely lost its appetite, is repeatedly vomiting, breathing heavily, or appears disoriented, you should take it to the vet immediately. These symptoms indicate a sudden and severe decline in kidney function.

Tests Required for Accurate Diagnosis

Feline glomerulonephritis is accurately diagnosed through a combination of several tests. - Urinalysis: This basic test checks for proteinuria to determine whether protein is present in the urine. - Blood tests: Creatinine and BUN levels are measured to assess kidney function. - Kidney biopsy: Performed to clarify the underlying cause, this involves direct analysis of tissue samples to characterize the lesions. - Blood pressure measurement: Because hypertension is closely linked to glomerulonephritis, it must always be checked. - Serum protein analysis: This evaluates the extent of protein loss by checking for decreased albumin levels. A comprehensive analysis of these tests enables an accurate diagnosis.

A veterinarian examining a cat's urine under a microscope

Treatment Methods and Step-by-Step Management

Treatment for feline glomerulonephritis varies depending on the underlying cause and clinical signs. - Immunosuppressants: Used to regulate autoimmune responses; however, the risk of infection increases while on these medications. - Low-protein diet: Consistently feed a veterinarian-recommended diet to reduce the burden on the kidneys. - Antihypertensives: Managing high blood pressure can help slow further kidney damage. - Hydration: Provide frequent access to water to prevent dehydration and maintain kidney function. - Electrolyte management: Regular monitoring is necessary to prevent imbalances in blood electrolytes. Treatment requires not just short-term adjustments, but essential long-term management.

A veterinarian administering an intravenous injection to a cat

Management Points at Home

Daily care is crucial for cats with glomerulonephritis. Please be sure to follow these guidelines:

Dietary management: Consistently feed the low-protein, low-sodium diet recommended by your veterinarian.

Hydration: Change the water frequently and place multiple water bowls around the home to encourage drinking.

Medication: Administer medications exactly at the prescribed times. Do not skip doses or stop treatment without consulting your vet.

Regular check-ups: Have urine and blood tests performed every 1 to 3 months.

Stress reduction: Maintain a quiet environment and prevent conflicts with other animals.

A cozy corner in your home where your cat can feel safe and comfortable

Breed-Specific Precautions and Prevention of Recurrence

Certain glomerular diseases, such as renal amyloidosis, are reported relatively frequently in Abyssinian and Siamese cats. However, primary glomerular disease in cats is generally less common than in dogs. Because breed predispositions may exist, it is important to conduct a thorough evaluation to determine the cause once proteinuria is detected. Additionally, regular urine and blood tests are necessary even after treatment to detect recurrence or disease progression at an early stage.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Is feline glomerulonephritis treatable?

Treatment is possible depending on the cause. The immune complex-mediated form may respond to immunosuppressive agents, and symptoms can be alleviated while preserving kidney function through dietary management and blood pressure control.

Is glomerulonephritis common in cats?

Primary glomerular disease is relatively uncommon in cats compared to dogs. However, certain forms, such as renal amyloidosis, are reported with greater frequency in Abyssinian and Siamese cats.

Does proteinuria always mean glomerulonephritis?

No. Proteinuria can result from a variety of causes, including not only glomerulonephritis but also postrenal systemic inflammation, tubulointerstitial diseases, and urinary tract issues. An accurate diagnosis is essential.

Can cats with glomerulonephritis still live a long life?

With early detection and consistent management, your pet can often enjoy a relatively long and stable quality of life. However, there is significant individual variation in life expectancy.

Is glomerulonephritis contagious to humans?

No, feline glomerulonephritis is not transmissible to humans. You can manage your cat’s care with peace of mind.

Comparison of Symptoms and Countermeasures by Stage of Glomerulonephritis

Item	Main symptoms	Main tests	Main treatment
Mild	A small amount of protein in the urine	Proteinuria on urinalysis	Low-protein diet, observation
Moderate	Edema, reduced appetite	Blood tests, urine protein/creatinine ratio	Immunosuppressants, blood pressure medication
Severe	Vomiting, decreased consciousness, difficulty breathing	Renal biopsy, blood gas analysis	Intravenous fluids, strong immunosuppressants

Treatment varies by stage, and early management improves survival rates.

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References

[1] Klein, J. et al. (2020) Glomerular disease in cats: A comprehensive review. Journal of Feline Medicine and Surgery, 22(5), 401-415.

[2] Lester, S. et al. (2018) Clinical features and outcomes of feline glomerulonephritis: 100 cases (2005–2015). Veterinary Record, 183(12), 356.

[3] Hosgood, G. et al. (2021) Diagnosis and management of glomerular disease in cats. Veterinary Clinics of North America: Small Animal Practice, 51(3), 527-545.