Protein Losing Nephropathy in Dogs

The kidneys are a critical organ responsible for filtering many waste products out of the bloodstream. Occasionally, the kidneys can become damaged or inflamed as a result of diabetes, autoimmune disorders, or blood clots. This can interfere with their normal function, causing stones, bloody urine, or loss of blood components beyond the waste material. Protein-losing nephropathy is a specific kind of kidney ailment that usually affects large-breed dogs, leading to the seepage of protein and blood serum into the urine. This disease often goes undiagnosed and can lead to fatal end-stage kidney failure if not caught and treated promptly.

Dog Breeds Affected

Common breeds affected include:

• Soft Coated Wheaten Terrier (especially common between the years of 2 – 6 years)
• Bernese Mountain Dog
• Labrador Retriever
• Golden Retriever

Females are historically more at risk than the males.

Protein-losing nephropathy is characterized by defects in the filtering system in the kidneys, leading to loss of protein and plasma from the blood rather than only the waste products meant to leave the body. This condition may arise idiopathically and often co-presents with hypertension.

• Abnormal behavior
• Weakness
• Refusal of food
• Vomiting
• Weight loss
• Excessive fluid buildup in tissues
• Abnormally low urine production relative to water intake
• Severe reaction to certain foods, this may include an adverse reaction to corn, tofu, cottage cheese, milk, lamb, and cream of wheat. Adverse reaction symptoms include diarrhea, vomiting, or chronic itching throughout the body.

• Autoimmune
• Diabetes
• Blood clot in kidney
• Parasitic infection
• Genetics
• Food allergy or intolerance

Protein-losing nephropathy can be difficult to diagnose, as the symptoms come on gradually and may go unnoticed for many years. Signs of a problem usually begin with a general lack of energy and decreased appetite, so be prepared to give the veterinarian a detailed account of any changes in your pet’s behavior, eating habits, or urination. The veterinarian will use these observations along with a physical exam to determine what tests to perform. A physical exam may reveal edema, which is the abnormal presence of fluid in your dog’s tissues.

The next line of diagnostic action will be blood and urine testing. These may require you to collect your pet’s urine at home, or for the vet to take a blood sample in the office. Protein-losing nephropathy will often reveal low levels of the protein albumin on a blood test due to the loss of protein through the urine. Excessive blood clotting factors and creatine will also be present.

The veterinarian will use an ultrasound to look for clots, stones, or other abnormalities. This is a non-invasive, real-time imaging system that can be done in even a small clinic. If any stones, clots or damage is found, an x-ray or CT scan may be needed. These often require larger facilities, and so you may be referred to an animal hospital for the images.

There is no real cure for protein-losing nephropathy. Treatment is aimed at preventing further damage to the kidneys, ameliorating the symptoms and fixing the underlying cause, if any. Drugs that inhibit Angiotensin Converting Enzyme (ACE) can be helpful in decreasing the amount of protein lost in the urine. Low doses of aspirin are also prescribed to prevent atypical blood clotting. The high blood pressure often seen in dogs with protein-losing nephropathy may be treated with beta-blockers or calcium channel inhibitors.

Parasitic infections that have become severe enough to cause organ failure are difficult to treat. High doses of antiparasitic medication place even more stress on the animal’s kidneys and run the risk of killing the dog as well as the parasites.

Sometimes the presence of parasites or food allergens can cause the body to attack its own tissue even after the parasite or food has left the body. In these cases, drugs that suppress the immune system can be effective if given in time.

The outlook is generally poor for dogs that have protein-losing nephropathy as the condition has usually advanced to a state beyond what a veterinarian can treat. Even with treatment and diet modification, affected animals only survive a few years.

However, if protein-losing nephropathy is caught early, and the cause is identified, successful treatment with the appropriate medication can save the animal. Diet modification may be needed, as certain foods such as wheat have chemical signatures very similar to the animal’s own body. If an allergic reaction occurs, some of the immune system components sensitized to the food allergen may misidentify the dog’s kidneys or gut lining as foreign. In this case, taking care to keep your dog away from the allergen combined with immunosuppressants carries an excellent prognosis.

Unfortunately, there is no cure for protein-losing-nephropathy. There are, however, a few different drugs that can help treat it. One category of drug that the veterinarian may prescribe is an angiotensin converting enzyme (or ACE) which decreases the amount of protein lost in urine. Enalapril is in the ACE category and can cost between $35 and $85 per 100 ct. Benazepril is another example and can cost between $15 and $55 per 100 ct. The veterinarian may also suggest low dose aspirin to help avoid blood clotting. Buffered aspirin helps minimize the inflammation or irritation while still allowing proper absorption. Buffered aspirin usually costs between $12 and $44 per 100 ct. Finally, the veterinarian may prescribe a beta-blocker or a calcium channel inhibitor that is used to treat high blood pressure that can occur in dogs with protein-losing-nephropathy. Amlodipine Besylate is a calcium channel inhibitor that can cost between $28 and $56 per 100 ct. However, Atenolol is a beta blocker that can cost between $15 and $25 per 100 ct.