🩺 Vet Guide 2025: Glomerulonephritis in Dogs and Cats – Protein Loss, Causes & Treatment 🐶🐱

By Dr Duncan Houston, BVSc

🔍 What Is Glomerulonephritis?

Glomerulonephritis is a form of kidney disease where the primary problem is excessive protein loss in the urine, rather than toxin buildup. Unlike typical kidney failure (uremia), this disease affects the kidney’s ability to retain valuable proteins, especially albumin. 🧪

🧬 The Role of the Glomerulus

The glomerulus is the microscopic filter in each nephron of the kidney. It allows waste and excess fluids to pass into the urine, while keeping essential proteins in the bloodstream. In glomerulonephritis, inflammation damages this filter, causing proteins to leak into the urine. This condition is referred to as proteinuria.

⚠️ Why Protein Loss Matters

Proteins like albumin are vital for:

• 💉 Maintaining blood pressure and fluid balance
• 🧬 Transporting hormones and nutrients
• 💪 Supporting muscle and tissue health

Loss of protein leads to muscle breakdown, weight loss, fluid accumulation (edema), and other complications.

🧪 Common Causes of Glomerulonephritis

It’s often triggered by chronic inflammation or immune system activity from conditions like:

• 🦷 Dental disease
• 🧴 Chronic skin or ear infections
• 🦟 Vector-borne diseases (Lyme, Ehrlichia, heartworm)
• 🎯 Immune-mediated disease or tumors

🩺 Diagnosing Protein-Losing Kidney Disease

1. Routine Urinalysis

Shows the presence of protein in the urine. Results are reported as "+", "++", or "+++". But concentration matters—a small amount of protein in dilute urine can be more significant than in concentrated urine.

2. Urine Protein:Creatinine Ratio (UPC)

This test quantifies protein loss and removes variability due to urine dilution. Results over 0.5 in dogs or 0.4 in cats are considered abnormal. Persistent elevations suggest glomerular disease.

3. Bloodwork

📉 A low albumin level raises concern. It’s critical to determine if the protein is being lost via the kidneys (as in glomerulonephritis), the intestines, or due to liver disease.

📊 Severity & Monitoring

The severity is gauged by:

• 📈 Urine protein:creatinine ratio (UPC)
• 🧪 Creatinine and SDMA (overall kidney function)
• 💉 Blood pressure
• 🩺 Albumin levels

UPC ratios > 3.5 are particularly concerning and require more aggressive diagnostics and treatment. In such cases, a kidney biopsy may be advised to classify the exact type of glomerular disease and whether immunosuppressive treatment is appropriate.

💊 Treatment Approaches

1. Diet Therapy

• 🥣 Low-protein, low-sodium renal diets reduce kidney workload
• 🫒 Omega-3 fatty acids help reduce inflammation and protein loss

2. Medications

• 🩺 ACE inhibitors (enalapril for dogs, benazepril for cats)
• 🧪 ARBs (losartan, telmisartan) – reduce proteinuria and blood pressure
• 🌀 Spironolactone – used in resistant dog cases to manage nephrotic syndrome

3. Monitor & Adjust

• 🔁 Goal: 50% reduction in UPC in dogs, 90% in cats
• 🩺 Recheck labs every 3 months or more frequently for unstable patients

🧨 Severe Complication: Nephrotic Syndrome

Nephrotic syndrome includes:

• 💧 Proteinuria
• 🩸 Low albumin
• 📈 High cholesterol
• 💥 Fluid buildup (edema/ascites)

🧠 This condition has a guarded prognosis, especially if accompanied by high blood pressure and high creatinine levels.

🔬 Kidney Biopsy: Pros & Cons

• 📈 Confirms the exact glomerular disease type
• 🧪 Useful for guiding immunosuppressive therapy
• 💉 Risk of bleeding; transfusion required in 10–17% of cases

A biopsy is typically reserved for high UPC, low albumin, or refractory cases where diagnosis will alter treatment significantly.

🩺 Final Thoughts from Dr Duncan Houston

Glomerulonephritis is a complex but manageable form of kidney disease in pets. Unlike standard kidney failure, the primary challenge is dangerous protein loss, not toxin buildup. Early detection, targeted medication, and consistent monitoring can help many pets live comfortable, fulfilling lives. 🐶🐱

📲 Need Help With Your Pet’s Kidney Health? Ask A Vet Now

If your pet has protein in their urine or is at risk for kidney disease, don’t wait. Download the Ask A Vet app to chat live with Dr Duncan Houston and get a tailored plan for testing, diet, and treatment 🩺🐾.