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Protein-Losing Nephropathy

Protein-Losing Nephropathy (PLN): An Overview

Protein-Losing Nephropathy (PLN) is a disease where the filtering mechanism of the kidneys is defective and the dog loses protein through urine. Because protein is such an essential nutrient to the body its loss is a very serious problem. Protein-losing diseases are complicated conditions rarely seen in general veterinary practice.

Certain breeds have a genetic predisposition to PLN and other protein losing diseases such as Protein-losing Enteropathy(PLE), especially the Soft Coated Wheaten Terrier. Veterinarians usually test Wheatens that exhibit symptoms. Most Wheatens affected by protein-losing disease are between the ages of two and six years; however, it has been diagnosed in dogs as old as eleven years. Females seems to be at more risk than the male. Other breeds at risk include the Bernese Mountain Dog, Labrador Retriever and Golden Retriever.

Affected dogs often have adverse reactions to food (diarrhea, vomiting, or intense itching). Most commonly implicated foods include corn, tofu, cottage cheese, milk, cream of wheat, and lamb.

Causes of Protein-Losing Nephropathy (PLN)

The exact cause or causes of PLN are still unknown. However, there is strong evidence that protein-losing diseases are genetically transmitted, but the exact mode of inheritance is not completely understood. In addition, infections and toxic substances may be potential causes. Another possibility is that affected dogs may be producing antibodies against their intestines and kidneys. A food allergy, particularly to glutens (the protein in wheat and other cereal grains such as rye, barley, or oats) in the diet may cause stimulation and thus the production of these antibodies.

Preventing Protein-Losing Nephropathy (PLN)

There is no way to prevent PLN, but blood and urine tests can determine whether or not a dog is clear of signs of disease, and help to establish baseline values for future comparison. Early detection can offer more choices for treatment and can often provide longer and better quality of life.

Symptoms of Protein-Losing Nephropathy (PLN)

One of the first signs of PLN in dogs is increased urination and drinking. Other signs include:

  • Listlessness/depression
  • Decreased appetite
  • Vomiting
  • Weight loss
  • Changes in skin and haircoat
  • Poor growth in young dogs
  • Ascites (accumulation of fluid in the abdominal cavity), edema (swelling,) pleural effusion (accumulation of fluid in the lining of the lungs and chest cavity)
  • Thromboembolic phenomena (obstruction of a blood vessel) and hypertension (high blood pressure, but is less common)

If your dog displays any of these signs or symptoms have him checked by your veterinarian as soon as possible. Wheatens with PLN may have serious thromboembolic events (such as pulmonary embolism) before symptoms or kidney failure start, even before there is increased serum creatinine or BUN.

Diagnosing Protein-Losing Nephropathy (PLN)

Diagnosing PLN is difficult. Your veterinarian can check for signs and perform blood and urine tests as follows:

  • Biochemical profile, including total protein (TP), albumin (Alb), globulin, creatinine (Cr), blood urea nitrogen (BUN), cholesterol (Chol), sodium (Na), potassium (K+), phosphorus (Phos), and complete blood count (CBC)
  • Routine Urinalysis, including specific gravity, dipstick and urinary sediment
  • Urine Protein/Creatinine Ratio
  • ERD or MA test for microalbuminuria (if doing UPC, these tests are not necessary)
  • Fecal API test

Laboratory abnormalities will include:

  • Hypoalbuminemia
  • Elevated serum creatine
  • Eosinophilia (high concentration of certain infection-fighting proteins in the blood)
  • Hypocholosterolemia (low cholesterol)
  • elevated urine protein/creatine ratio
  • hypercoagulopathy (excessive blood clotting)

Treating Protein-Losing Nephropathy (PLN)

Treatment of PLN is aimed at managing symptoms and slowing disease progression and kidney failure. Angiotensin converting enzyme (ACE) inhibitors, such as analapril are frequently used to decrease the degree of proteinuria (protein in the urine). Dogs that have serum albumin of < 2.0 g/dl should be given a low-dose of aspirin to help prevent thromboembolic disease. Systemic hypertension must be controlled. Dogs with PLN should be fed a gluten-free (no wheat) diet that is moderately reduced in protein. Protein sources should come from fish, venison, or other protein source not common in commercial dog food, including chicken.

Caring for Dogs with Protein-Losing Nephropathy (PLN)

There is no cure for PLN, and the prognosis is poor. However there are things you can do to improve your dog's life and lifespan in addition to administering medications. Limit any environmental stressors your dog may experience. Do not breed affected females not only because the disease is hereditary, but also because whelping will exacerbate the disease. Provide a healthy diet and do not make frequent dietary changes.

The AKC Canine Health Foundation and Protein-Losing Nephropathy (PLN)

Three grants have been funded by CHF to study the mode of inheritance and genetic causes of Protein-Losing Nephropathy (PLN) in the Soft Coated Wheaten Terrier.

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