Kidney Disease in Dogs – Nephrotic Syndrome: A Potential Complication in Glomerulonephritis or Renal Amyloidosis

Canine nephrotic syndrome is a result of damage to the kidneys of the dog. Kidney disease and/or kidney failure is the primary cause of nephrotic syndrome. Nephrotic syndrome is relatively rare in dogs but can be life-threatening and even fatal when it occurs.

Diagnosis of Canine Nephrotic Syndrome

Nephrotic syndrome in dogs is diagnosed by the presence of:

  • low albumin levels in the blood
  • high levels of urea nitrogen in the blood
  • abnormally high levels of protein in the urine
  • high blood cholesterol levels

Urine protein:creatinine ratios help quantify protein levels found in the urine in relationship to the water consumption of the animal. Urine cultures test for urinary tract infections which may also affect the protein levels found in urine. These tests may be necessary to determine whether protein found in the urine is the result of kidney disease or other urinary tract disease. Routine blood screens will quantify albumin blood levels, blood urea nitrogen levels and cholesterol levels in the blood. Edema (swelling of tissues) and other abnormal fluid accumulation may occur in canine nephrotic syndrome due to osmotic abnormalities resulting from protein loss.

Kidney Disease Causes Nephrotic Syndrome in Dogs

Canine nephrotic syndrome results from damage to the kidneys and is usually the result of:

  • glomerulonephritis – inflammation in the kidney resulting in excessive protein loss through the kidney.
  • renal amyloidosis – deposition of amyloid (a glycoprotein) within the architecture of the kidney which leads to renal disease and protein loss through the kidneys.

Both glomerulonephritis and renal amyloidosis can have many causes. Approximately 15% of dogs with glomerulonephritis develop nephrotic syndrome. However, nephrotic syndrome may be more commonly encountered in dogs suffering from renal amyloidosis, although renal amyloidosis is a relatively rare condition.

Symptoms of Nephrotic Syndrome Caused by Protein Loss Resulting from Kidney Disease or Failure

Symptoms of nephrotic syndrome are the direct result of the protein loss which occurs in kidney disease or kidney failure. Hypercholesterolemia (elevated blood cholesterol levels) can also play a role in the development of symptoms.

Symptoms commonly seen with canine nephrotic syndrome include:

  • swelling, especially in the legs
  • abnormal accumulation of fluid in body cavities
  • hypertension (high blood pressure)
  • thromboembolic disease (abnormal blood clots)
  • disseminated intravascular coagulation, also known as DIC (a disorder causing abnormal bleeding deficits)

Treatment of Nephrotic Syndrome in Dogs

Nephrotic syndrome is a serious complication to kidney disease and can be difficult to treat. Treatment involves treating the underlying cause of the protein loss, which can be difficult in some cases to determine.

Diuretics such as mannitol or dextrose solutions, or even furosemide (Lasix®) may be necessary in treating nephrotic syndrome in order to decrease the metabolic wastes and improve the kidney function.

Other treatments frequently necessary in treating kidney disease and/or kidney failure may also be necessary in treating nephrotic syndrome and may include:

  • antibiotics, if infection is present
  • fluid therapy, to correct dehydration and replace potassium and proteins as necessary
  • dietary restrictions, such as salt, phosphorus and sometimes protein restriction
  • aspirin (low dose aspirin therapy to control thromboembolism, as necessary)
  • phosphate binders, such as aluminum hydroxide and many others, if phosphate levels are elevated
  • antiemetic medications to control vomiting, if necessary
  • medications to reduce gastric acidity, modify gastrointestinal motility and protect against gastrointestinal ulceration, as necessary
  • medications to control hypertension, as necessary
  • angiotensin converting enzyme (ACE) inhibitors, such as enalapril and benazepril
  • vitamin B complex and vitamin C supplementation
  • calcitriol to decrease levels of serum parathyroid hormone (PTH), in some cases
  • peritoneal dialysis
  • usage of immunosuppressive medications, such as glucocorticoids, azathioprine and cyclosporine is controversial but used in some situations

Renal Disease and/or Kidney Failure and Nephrotic Syndrome in Dogs

Nephrotic syndrome is a serious complication to kidney disease in dogs, usually resulting from glomerulonephritis or renal amyloidosis. The resultant kidney disease and/or kidney failure results in renal damage which allows excessive protein loss through the urine. Though rare, the syndrome is life-threatening and potentially fatal.