The kidneys consist of many thousand microscopic filtering units called glomeruli that filter water and small substances from the bloodstream. The tubules of the kidney then reabsorb vital substances such as glucose and electrolytes from the filtered fluid leaving unneeded substances and a small amount of water in the urine.
Glomerulonephritis is inflammation of these microscopic filtering units of the kidneys that develops when immune complexes (complexes of antibodies and antigens) become trapped in the glomeruli, leading to activation of the body's inflammatory defense system, which, in turn, damages the glomeruli. The immune complexes often form as a consequence of some other disease process such as infection or cancer. However, in many cats with glomerulonephritis, the inciting cause cannot be found and the problem is said to be idiopathic.
Glomerulonephritis results in excessive loss of protein into the urine (proteinuria). The finding of protein in the urine on urinalysis may be the first indication that your pet has glomerulonephritis. Untreated, the disease can lead to chronic kidney failure.
Cats of any age, breed or gender can develop glomerulonephritis. In many pets, there may be no obvious symptoms of glomerulonephritis.
What to Watch For Swelling of the abdomen
Swelling of the paws, hocks (ankles), face or scrotum
Increased water consumption
Increased urination
Weight loss
Lethargy
Vomiting
Sudden loss of vision
Sudden difficulty breathing
Diagnosis
Diagnostic tests are needed to identify acute glomerulonephritis and exclude other diseases. These may include:
Urinalysis to identify proteinuria or hyaline casts, which are protein molds of the renal tubules.
Complete blood count (CBC) to identify anemia, inflammation, infection or low platelet count
Serum biochemistry tests to identify low blood protein concentration and high blood cholesterol concentration
Urine protein/creatinine ratio to determine the severity of protein loss in the urine
Blood pressure measurement to identify systemic hypertension
Kidney biopsy to identify glomerulonephritis conclusively and differentiate it from amyloidosis, which is another kidney disease that affects the glomeruli
Treatment
The ideal treatment for glomerulonephritis is to identify any underlying infectious, inflammatory or cancerous disease that may be causing production of immune complexes that are being trapped in the glomeruli. Unfortunately, in many cases of glomerulonephritis, no underlying disease process can be identified, or if one can be identified, it cannot be eliminated.
Immunosuppressive drugs can be administered to suppress immune complex formation. Drugs used for this purpose are cortisone-like drugs like prednisone.This is is not common practice as there has been no scientific evidence that this is beneficial.
A very low dose of aspirin may be prescribed to prevent clotting within the glomeruli.
Specialized diets may be used in some instances.
Low protein, low phosphorus diets should be given to pets in kidney failure.
Low sodium diets should be given to pets with hypertension.
Diets supplemented with omega-3 fatty acids to limit the inflammatory response.
Medications may be prescribed to control blood pressure in pets that are hypertensive.
Drugs called angiotensin converting enzyme (ACE) inhibitors like enalapril may be used to minimize protein loss in the urine and to help control blood pressure.
Home Care and Prevention
Administer as directed any medications prescribed by your veterinarian. Follow any dietary recommendations and schedule regular follow-up visits with your veterinarian to monitor your pet's progress.
Observation is important. Make sure your pet's activity level, appetite and attitude remain normal. Watch for difficulty breathing or limb weakness that may indicate development of thromboembolism. Observe your pet for loss of vision that could indicate complications of hypertension. Look for swelling of the paws, hocks or face that could indicate development of subcutaneous edema and for swelling of the abdomen that could indicate fluid accumulation.
Glomerulonephritis is difficult to prevent. Certain infectious, inflammatory and cancerous diseases can lead to development of glomerulonephritis and regular annual examinations by your veterinarian are advised to be certain your pet remains healthy and free of such diseases.
