Kidney failure, also called renal failure, occurs when the kidneys fail to
remove metabolic waste products from the blood. Toxic levels of these waste products accumulate in the blood, creating a condition called uremia and producing signs of illness throughout the body. Kidney failure can occur suddenly (acute renal failure) or develop gradually over several months (chronic renal failure).
Chronic renal failure is the most common form of kidney failure, and the cause is often unknown.
Some causes of acute renal failure include:
- poisoning, especially with antifreeze (ethylene glycol)
- complete blockage of the urinary tract from a bladder or urethral stone
- heat stroke and shock, which result in inadequate blood flow to the kidneys
- infections, such as leptospirosis
- treatment with certain medications, such as aminoglycoside antibiotics; nonsteroidal anti-inflammatory drugs, including ibuprofen, naproxen, and phenylbutazone; and certain anticancer agents.
Signs of kidney failure don’t occur until dogs lose 75 percent of their kidney function.
Risk factors and detection
Kidney failure occurs in dogs of all ages, but it’s most common in older dogs. Dogs who roam freely are at greater risk of developing kidney failure from toxins and infectious agents. Heredity also plays a role, and certain breeds have a higher incidence of kidney failure, including basenjis, beagles, Bedlington terriers, Bernese mountain dogs, bull terriers, Shar-Peis, chows, cocker spaniels, Doberman pinschers, German shepherds, golden retrievers, keeshonds, Lhasa apsos, miniature schnauzers, Newfoundlands, Norwegian elkhounds, Welsh corgis, Samoyeds, Shih Tzus, Soft-coated wheaten terriers, and Standard poodles.
Metabolic diseases that raise the level of calcium in the blood, such as hyperparathyroidism, vitamin D toxicity, and some cancers, also can cause kidney failure.
Signs of kidney failure include:
- increased thirst
- increased urination
- housesoiling or urinating during the night
- dehydration
- inability to urinate
- unexplained weight loss
- appetite loss
- lethargy
- anemia (look for pale gums)
- vomiting.
If you observe any of these signs in your dog, see your veterinarian immediately. Your doctor will ask about your dog’s medical history, changes in his habits or behavior, and his environment. To determine the cause and severity of the disease, the veterinarian will perform a complete physical examination and may recommend blood and urine tests, X-rays, an ultrasound, and a kidney biopsy.
Prevention and treatment
You can prevent toxic and infectious causes of kidney failure by keeping your dog inside. Also, be extremely careful when handling antifreeze to avoid spills—this fluid is sweet and appealing to dogs and is toxic in small doses. Vaccinate your dog against the bacterial infection leptospirosis, and if you have an older dog, request routine blood and urine tests to monitor kidney function. Keep in mind that annual physical examinations, including the blood and urine tests, help your veterinarian detect and treat kidney failure early—before disease progresses.
If your dog suffers from kidney failure, treatment will depend on the cause
(if known), whether the kidney failure is acute or chronic, and whether the kidneys are producing urine. Some treatment options include:
Hospitalization. Your dog will require hospitalization if he has acute kidney failure or is experiencing severe signs of chronic kidney failure. If your dog is producing little or no urine, your veterinarian may administer medications, such as diuretics and vasodilators, to initiate urine production. Peritoneal dialysis may be attempted while waiting for urine to be produced. (Peritoneal dialysis involves putting sterile fluid into the abdomen to draw out waste products from the dog’s blood. The fluid and wastes are then removed from the body.)
Fluid therapy. While your dog is hospitalized, he may receive intravenous fluids to correct dehydration and electrolyte abnormalities. If your dog has chronic kidney failure, he may receive subcutaneous fluids (fluids administered under the skin) periodically to maintain hydration.
Dietary management. Many dogs with kidney failure benefit from eating an
easily digested food with restricted levels of protein and phosphorus. These foods reduce the amount of metabolic waste products that the kidneys must handle. Your veterinarian will give you specific instructions for feeding your dog either a therapeutic diet or a homemade food that meets the special needs of kidney-failure patients.
Antibiotics. If the cause of kidney failure is a specific bacterial infection, your dog will begin antibiotic therapy. If your dog’s immune system is suppressed, your veterinarian also may prescribe antibiotics to treat other infections that occur while your dog is in a weakened state.
Antitoxins. If your veterinarian diagnoses antifreeze toxicity in your dog, he or she will recommend treatment with ethanol. An alternative treatment for dogs is 4-methylpyrazole, a commercially available drug.
Complications
Other treatments are aimed at controlling complications from kidney failure and uremia, such as:
Vomiting and gastritis (stomach inflammation). Kidney failure increases the stomach’s acidity and makes patients more susceptible to stomach ulcers and bleeding. Such patients often require an antacid, such as cimetidine or ranitidine, or a stomach protectant, such as sucralfate. Medications such as metoclopramide or chlorpromazine help control vomiting.
High blood pressure (hypertension). Many dogs with kidney failure develop dangerously high blood pressure. The drug enalapril can control the problem.
High blood phosphorus levels. Many dogs with kidney failure have abnormally high levels of phosphorus in their blood, which contributes to lethargy and poor appetite. These dogs should eat a low-phosphorus diet. And they may benefit from oral phosphate binders, which lower the amount of phosphorus absorbed through the digestive tract.
Anemia. A reduction in the number of red blood cells or quantity of hemoglobin in the blood is a serious complication in many patients. Treatment includes administering erythropoietin and anabolic steroids to stimulate red blood cell production. Unfortunately, some dogs can’t take erythropoietin long-term because the immune system recognizes the drug as "foreign" and makes antibodies to fight it.
Appetite loss. If your dog has kidney failure, you may have to entice him to eat. Heating the food or switching to a moist food might make the diet more appealing.
Prognosis
Some cases of acute kidney failure are reversible. However, most acute cases are severe, and dogs who produce little or no urine usually die. A dog who survives acute kidney failure may need four to 12 weeks to regain kidney function.
Dogs with chronic kidney failure have a progressive, irreversible disease. No cure exists, but with proper management, many of these dogs live comfortably for years.
