Glomerulopathies are one of the most important causes of kidney disease and kidney failure in dogs. Glomerulonephritis is the most common type of canine glomerular disease diagnosed.
Glomerulonephritis in dogs is a kidney disease which results from inflammation within the glomeruli (a functional part of the kidney) which leads to abnormal filtration and protein loss through the kidneys. Glomerulonephritis is a process which is different from that which causes azotemia or uremia, conditions in which waste products produced by the body build up within the blood stream. Though uremia can be present concurrently, glomerulonephritis may also occur without the presence of azotemia or uremia.
Causes of Glomerulonephritis and Other Glomerulopathies Which May Cause Kidney Disease in Dogs
Inflammation is the primary cause of damage to the glomeruli which ultimately causes glomerulonephritis. Chronic inflammation in particular is often involved and may result from a number of different sources, including:
- bacterial infections, such as Lyme disease, ehrlichiosis, brucellosis and others
- viral infections, such as adenovirus
- protozoal infections, such as trypanosomiasis and babesiosis
- parasitic infections, such as heartworms
- autoimmune diseases, such as systemic lupus or lupus nephritis, and
- cancers, such as lymphosarcoma, carcinoma, leukemia and other cancers.
Infections resulting in glomerulonephritis may originate in:
- the skin,
- the ears,
- the uterus (pyometra),
- the intestinal tract (inflammatory bowel disease),
- the pancreas, or
- may be the result of dental disease (gingivitis and other dental infections).
Some breeds of dog may also be predisposed to an inherited or congenital form of glomerular disease, including:
- Bernese Mountain Dogs
- Bull Terriers
- Cocker Spaniels (especially English)
- Dalmation
- Doberman Pinscher
- Newfoundland
- Shar Pei
- Soft-coated Wheaten Terrier
Symptoms of Kidney Disease Caused by Glomerulopathies in the Dog
Symptoms of kidney disease which result from glomerulonephritis vary depending on the cause and the severity of the disease. Some dogs may appear to be normal and healthy, while others may be lethargic and suffer from weight loss. Other dogs may suffer ascites (fluid within the abdominal cavity) or swelling of the limbs. Still others may develop symptoms consistent with kidney failure, including increased thirst, increased urine volume, vomiting, lack of appetite and foul breath. In some situations, symptoms may be more indicative of the underlying disease, as in heart failure with dogs infected with heartworms.
Nephrotic Syndrome is a Severe Complication of Kidney Disease Caused by Glomerulonephritis
Nephrotic syndrome is a serious complication of glomerulonephritis which results from the loss of excessive amounts of protein. Dogs with nephrotic syndrome will experience swelling in the legs and/or ascites, hypertension (high blood pressure) and an abnormal tendency to produce blood clots leading to thromboembolic disease.
Diagnosing a Glomerulopathy and/or Glomerulonephritis in a Dog
Finding protein in the urine is the hallmark of diagnosing glomerulonephritis and/or glomerulopathy in dogs. However, inflammation within the lower urinary tract must also be ruled out as a cause of the protein in the urine. Blood in the urine from lower urinary tract disease will also affect the measurement of protein in the urine.
Urinalysis (examination of the urine for specific types of cells, chemicals and other substances) is one of the most commonly used tests. However, the measurement of urine protein:creatinine ratios may be necessary to more accurately measure the amount of protein present in the urine in relation to the amount of water consumption and the relative concentration of the urine.
Routine blood testing may reveal low blood protein levels, particularly albumin (a specific type of protein). Other abnormalities seen may include elevated blood cholesterol levels, anemia and clotting abnormalities, including decreased thrombocyte (blood platelet) counts. Elevations in blood urea nitrogen (BUN), elevations in blood creatinine levels, and elevated blood phosphate levels are also possible.
Blood pressure should also be monitored in dogs suffering from glomerulonephritis or any other type of kidney disease as hypertension is a common finding in canine kidney disease.
Renal biopsy may be necessary to provide a definitive diagnosis as to the cause of kidney disease, but may not advisable in all cases.
Treatment of Canine Glomerulonephritis
Where possible, treatment of the underlying disease is the most important step in treating glomerulonephritis.
Specific treatment for glomerulonephritis may include:
- angiotensive-converting enzyme (ACE) inhibitors, such as enalapril and benazepril
- feeding of a kidney diet, which may involve restricted protein, salt and phosphorus levels and addition of omega 3 fatty acids
The use of immunosuppressive medications, such as glucocorticoids, azathioprine or cyclosporine, is controversial and generally not recommended except in the case of immune-mediated diseases which are responsive to immunosuppression.
Glomerulopathy and Glomerulonephritis is a Frequent Cause of Canine Kidney Disease and Renal Failure
Glomerulopathies, most often caused by glomerulonephritis, are a common cause of kidney disease in dogs. Canine glomerulonephritis may also cause kidney failure and there are many different disease processes which may result in glomerular damage and disease.
Sources:
Vaden, SL, "Glomerulopathy in Dogs", American College of Veterinary Internal Medicine Conference Proceedings, 2003.
Sykes, J. "Mechanisms of Renal Injury by Infectious Agents", American College of Veterinary Internal Medicine Conference Proceedings, 2003.
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