Chronic Kidney Disease in Dogs
Chronic kidney disease, also known as chronic renal failure, is a progressive loss of kidney function over a period of time. The kidneys have many functions. Overarching, they filter out waste products from the blood stream, regulate ions levels, conserve water, and produce urine. Chronic kidney disease is the kidneys’ inability to remove the body’s waste from the blood efficiently. In dogs, chronic kidney disease is associated with aging, and can be considered as the ‘wearing out’ of the kidney tissues. Kidney tissue cannot regenerate if destroyed. At least 2/3 of the kidneys must be dysfunctional before any clinical signs of kidney disease are seen. This means, in many cases, that the destruction has been occurring for months to years before being detected. The age of onset is relative to the size of the dog. Commonly smaller dogs live longer lives, so the early signs of kidney disease occur at about 10 to 14 years of age. Larger dogs with typically shorter lifespans may start to see signs as early as 7 years of age.
When advanced age or the disease causes the filtration process of the kidneys to become compromised or ineffective, blood flow to the kidneys is increased in an attempt to increase filtration. Because fewer toxins are being removed from the blood each time, the body must increase the amount of blood flowing through the kidneys. This increased flow results in more urine being produced. When the urine output is increased the water intake must also be increased to avoid dehydration. This is why a clinical sign of kidney disease is an increase in a dog’s thirst and urge to urinate. This symptom is referred to as compensated renal failure. As the disease progresses more wastes can be found in the dog’s blood and the clinical signs become more severe including: loss of appetite, depression, vomiting, and bad breath.
Chronic kidney disease can be diagnosed using blood tests and urinalysis. In the blood the levels of blood urea nitrogen (BUN) and blood creatinine (CREA) are examined. Although these levels reflect kidney failure, they cannot predict it. A dog with marginal kidney failure can have normal appearing blood tests.
Treatment of kidney disease is dependent on the degree of deterioration of the kidneys. Unfortunately, in some cases the kidneys are damaged beyond repair before diagnosis. However, with early detection and aggressive treatment dogs with kidney disease can live for many months to years. Treatment is typically a two-step process. The first step is to flush out the kidneys and bloodstream. This process is called diuresis and is done by giving large amounts of IV fluids. This helps the damaged kidney cells to function again by removing the toxic materials and creating a healthier environment. If enough functional kidney cells remain, they may be able to meet the body’s filtration needs. If the first step is successful, the dog can proceed to step two. The second step of treatment is to help keep the kidneys functioning for as long as possible. This can be done though home fluid therapies, special diets and drugs to keep phosphorous levels low, and several other options that can be discussed with your veterinarian.
Life expectancy for a dog living with kidney disease is variable depending on the dog’s response to initial treatment and ability to maintain treatment moving forward. Always discuss all options with your veterinarian. Treatment options can be relatively inexpensive and they have the opportunity to extend length and quality of your dog’s life.
Blog by: Nicole Lathrop