Causes of Chronic Renal Failure in Dogs
The term “chronic” in chronic renal failure means that the process has been ongoing, is progressive, and unfortunately, cannot be reversed. For some dogs, the disease could have occurred after a serious kidney injury such as from a severe infection (i.e., leptospirosis, pyelonephritis) or ingestion of a toxic substance such as anti-freeze, grapes, or raisins, and certain antibiotics.
For others, it could be inherited, such as with glomerular disease (a specific type of renal kidney disease) and amyloidosis (a rare organ disease) as seen in breeds like the Bernese Mountain Dog and Shar-pei.
For others, it could be attributed to underlying immune-mediated diseases, stroke-like events, or even from clotting disorders. In cases for newly diagnosed dogs the underlying cause will likely remain unknown.
Symptoms of Chronic Renal Failure in Dogs
Clinical signs are often related to the severity of the CRF stage, meaning there are additional and more severe signs noted with stages III and IV than there are with stages I and II. Dogs often exhibit symptoms including:
Some dogs may show muscle wasting and signs attributed to high blood pressure, such as vision loss and weakness.
Diagnosing Kidney Disease in Dogs
It is important to know that chronic kidney disease signs typically do not appear until the disease has progressed to a certain point. This is why it is so important to bring your dog to the vet for routine exams and follow your vets recommendations for routine lab work. Screening healthy dogs allow vets to detect small changes over the years. Kidney disease may be detected early, and treatment can begin before your dog even gets sick.
If you notice signs of kidney disease or any other signs of illness, it is essential that you take your dog to the veterinarian right away for a physical examination. Next, your vet will likely recommend laboratory tests including:
The results of these tests can usually give your vet enough information to diagnose kidney disease. When kidney disease is present, the BUN and creatinine will be elevated. These chemicals build up when the kidneys arent filtering the blood properly. Blood phosphorus levels may also be high. The urine is often diluted and may have excess protein—an indication that the body is losing protein because the kidneys cannot properly filter. Anemia might be noted on the CBC as this is sometimes caused by kidney disease.
Once a diagnosis of kidney disease has been made, further tests may be warranted to determine how severe the disease has progressed. Blood pressure measurement is an important test because hypertension is common in dogs with kidney failure. Your vet may also recommend abdominal radiographs (X-rays) and/or abdominal ultrasounds.
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Once your vet has a complete picture of your dogs health, a treatment plan will be developed based on your specific dogs condition. Lab tests must be repeated often. Treatments are adjusted according to the results, which usually change over the course of the illness.
Dogs being treated for acute renal failure may need lab work one or more times per day. For dogs with chronic kidney failure, lab tests are usually repeated every few weeks to months (depending on how the dog is doing).
Fluid therapy is the cornerstone of kidney disease treatment. Intravenous (IV) fluid diuresis is necessary to treat acute renal failure. It may also be used when a chronic kidney is first diagnosed. IV fluids are administered through an IV catheter at a rate to flush the system of toxins. Care is taken to avoid a fluid rate high enough to negatively impact the dogs heart. Dogs with kidney disease may need to be on IV diuresis for several days, during which they must stay in the hospital.
Dogs with chronic kidney disease are often maintained on subcutaneous fluids given by the owner at home. This involves placing a needle under the loose skin between the shoulder blades and infusing a set amount of fluid. This may need to be done daily or only a few times a week. Your veterinarian will show you the simple process for giving your dog fluids at home, which maintains hydration and provides extra fluid to support the kidneys.
Therapeutic diets are often used to manage chronic kidney disease. It is believed that adjusting the levels of certain components in the diet can lower the burden on the kidneys. Therapeutic kidney diets are often low in protein, phosphorus, calcium, and sodium. Palatability is a common issue with these diets, but several commercial brands are available to try.
Medications and supplements are used for a variety of reasons. Phosphate binders taken with food can decrease the amount of phosphorous the body absorbs, lessening the burden on the kidneys (which normally filter phosphorous out of the blood). Antacids are used to reduce the excess acid produced in the stomach (this occurs when the pH is not well-regulated by the kidneys). Antiemetics help relieve nausea and vomiting often caused by kidney disease, sometimes improving appetite. ACE inhibitors can control protein loss through the kidneys and help regulate blood pressure. Additional blood pressure medications may be necessary. Certain vitamins and supplements may be recommended based on your dogs needs and your vets opinion.
Dialysis is not commonly used due to its expense and scarcity. This treatment involves the use of a machine that filters the blood. Dialysis is generally only offered at certain large specialty hospitals. Dogs with acute renal failure may benefit most from dialysis if it is available.
A kidney transplant is rare. This expensive, high-risk procedure is only performed by certain veterinary surgeons.