Kidney failure, or chronic kidney disease, is a progressive disease that gradually diminishes the kidneys' ability to remove waste from the body. Kidney failure is a disease of aging in dogs as it often occurs as a result of the organs' tissue wearing away. Other diseases and conditions might also cause damage resulting in kidney failure.
Symptoms of chronic kidney disease rarely present until the disease has progressed irreversibly. Though kidney failure is incurable, treatment is available to slow the progression of the disease and to relieve accompanying symptoms.
The primary role of the kidneys in the body is to remove waste from the bloodstream. Waste, including toxins, by-products of metabolism, and old cells, is excreted from the body in urine. Kidneys also regulate minerals, water, and sodium in the bloodstream and aid in the formation of red blood cells.
The kidneys are composed of thousands of microscopic filters called nephrons. Each kidney contains a finite reserve of nephrons that replace those that die through the natural aging process or due to damage.
Chronic kidney disease is characterized by the kidneys' inability to remove waste from the bloodstream adequately. As nephrons gradually die, kidney damage occurs progressively. Symptoms of kidney disease, however, don't typically present until 75% of nephrons have died. By this time, the many vital functions of the kidney are affected, and the damage is irreversible.
Chronic kidney disease in dogs stems from several other diseases and conditions as well as the normal aging process. Diseases and conditions include pervasive infection in the kidneys, high blood pressure, immune system disease, and acute kidney disease.
The root cause of chronic kidney disease is often unknown, however. By the time the disease is discovered, the underlying disease or condition has resolved, and the dog has progressed into kidney failure.
Increased water intake and urination, and sometimes incontinence, are often the earliest symptoms of chronic kidney disease in dogs. A dog may also experience gastrointestinal upset, decreased appetite and accompanying weight loss, anemia, weakness, and depression.
Less common but more grave symptoms may include bone fractures, blindness, bruising, and abdominal bleeding.
Chronic kidney disease is often diagnosed during a dog's regular veterinary exam or a visit following the appearance of abnormal behavior. A blood test and urinalysis are necessary to diagnose CKD. Elevated levels of creatinine and blood urea nitrogen in the blood and increased protein and phosphorus in the urine reveal evidence of impairment in the function of the kidneys.
Veterinarians stage kidney failure according to the International Renal Interest Society, or IRIS. Stages range from 1 to 4, with 4 representing the most progressive stage of kidney failure. The stages correspond to the levels of creatinine in the blood and protein in the urine, and blood pressure. Staging kidney failure assists veterinarians in choosing the most appropriate treatment option.
Chronic kidney disease in dogs is incurable, but the disease's progress can be slowed, and symptoms can be treated. Treatment is administered in phases, with the second phase depending on the success of the first. Phase one treatment consists of flushing the build-up of waste from the kidneys and bloodstream with intravenous fluids. If phase one is successful, the remaining nephrons will resume normal function in the kidneys.
The purpose of the second phase of treatment is to support the function of the kidneys, stave the disease's progress, and manage symptoms. This involves a specialized diet, fluid therapy, and medicines.
Adherence to a special diet is essential in prolonging the functioning of a dog's kidneys and slowing further damage. A dog in kidney failure should eat a diet low in phosphorus, sodium, and protein. Omega-3 fatty acids may counter the decline in kidney functioning. Kidney failure may put a dog at risk for acidosis, so the diet must also be non-acidifying.
A dog's prognosis depends on the stage of kidney failure, response to the first phase of treatment, and home care. If a dog responds well to treatment in this phase and receives ongoing treatment and care, it may live for several years following diagnosis. With proper follow-up care at home, a dog with chronic kidney disease can maintain a relatively high quality of life.
Staging the disease allows the veterinarian to determine the dog's prognosis.
Committed and thorough care at home is vital to a dog's survivability and quality of life in kidney failure. This includes sticking to the specialized diet prescribed by a veterinarian and maintaining regular appointments to monitor the disease. Ensuring a comfortable and stress-free environment for the dog is absolutely essential, as well.
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