Glomerulonephritis in Cats

The term glomerulonephritis refers to the inflammation and subsequent dysfunction of the glomeruli -- the small mass of capillaries in the kidney that filters waste products from the blood and into the urine so they can be secreted from the body. The most common cause of glomerulonephritis is the deposition and entrapment of antigen-antibody complexes (such as a toxin or enzyme) within the glomeruli. Moreoever, the disease affects both genders, but occurs in more often in males.

Symptoms and Types

Symptoms may vary depending on the underlying cause, like inflammation, infection, or neoplasia. In some cats, the only presenting symptom may be weight loss and weakness. In fact, many times, the condition is discovered incidental to a routine annual health screening, when increased concentrations of proteins are found in the urine. If the protein loss into the urine is severe, the cat may develop an abnormal collection of fluid in the abdominal cavity (ascites).

In cats suffering from advanced disease with kidney failure, there may be symptoms of increased thirst and frequency of urination, lack of appetite, nausea, and vomiting. Those with a severe deficiency of the blood protein albumin (hypoalbuminemia), may suffer from a blockage of the lung's blood vessels, which causes respiratory difficulties or severe panting. High blood pressure, meanwhile, may cause sudden blindness.

Causes

• Inflammation
• Infections
• Idiopathic (unknown)
• Neoplasia (growth of tissue, tumor)
• Diabetes mellitus
• Long-term use of certain drugs

Diagnosis

You will need to give a thorough history of your cat's health, onset of symptoms, and possible incidents that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. The results of the complete blood count test are usually not significant. In severe cases, the biochemistry profile may reveal abnormally low levels of blood protein albumin (hypoalbuminemia) and high levels of cholesterol in the blood (hypercholesterolemia). The presence of blood protein albumin and other proteins in the blood may help your veterinarian in making the initial diagnosis. In cats with kidney failure, the urinalysis will reveal corresponding changes in urine.

Creatinine is a waste product normally excreted by the kidneys, and its presence in the urine is measured as a diagnostic indicator of kidney function. Urine protein testing is also performed, as the amount of protein found in the urine can also be used to evaluate and monitor kidney function.

A more specific test calculates the urine protein and creatinine ratio in order to give your veterinarian an idea of the degree of kidney damage. The extent of protein loss in the urine roughly correlates with the severity of the kidney disease. Therefore, measuring protein and creatinine ratio also helps in assessing treatment response and progression or regression of disease.

Diagnostic imaging can also be used for determining how diseased your cat's condition is, and what treatment needs to be applied. These procedures are helpful in the diagnosis of concurrent diseases and in evaluating the kidney size. Abdominal X-rays and ultrasound can be used to evaluate the kidneys and other abdominal organs, and can be helpful in performing a less invasive type of tissue collection for biopsy purposes. Your veterinarian may take a kidney tissue sample (kidney biopsy) to rule other causes of kidney failure, such as neoplasia or cancer.

Treatment

As most cases of glomerulonephritis involve an immune reaction (interaction of antigen and antibodies), the most specific and effective therapy is the control and elimination of such an immune reaction. However, finding and treating the exact disease process or antigen that is causing such an immune reactions is not always possible. Moreover, once renal failure has developed, the prognosis is often poor. The overall treatment of this disease depends on the cause and severity of the disease at the time of diagnosis.

Living and Management

Your veterinarian will recommend an individualized diet plan for your cat that is tailored toward kidney health. These patients often require low sodium and high quality, low quantity, protein diets. Because most drugs are eliminated through the kidneys, do not give your cat any types of drugs, or change the dosage of any prescribed drugs without consulting your veterinarian beforehand. In follow-up visits, your veterinarian will need to conduct regular laboratory testing in order to monitor the therapy response and progression of the disease, adjusting medications and therapies as necessary.