Chronic Kidney Disease in Senior Dogs

Chronic kidney disease, also known as chronic kidney or renal failure, is one of the most common age-related conditions in senior dogs. Unlike acute kidney failure (occurring suddenly, it’s mainly caused by the ingestion of a toxic substance like antifreeze or by an inadequate flow of blood to the kidneys), chronic kidney failure is a progressive disease in which a dog’s kidney function declines over months, even years, before any symptoms appear.

Small breed dogs may show early signs of kidney damage at 10 to 14 years of age, whereas large breed dogs with shorter life spans will show signs earlier. While the damage to their kidneys is irreversible, supportive treatment can often improve a dog’s quality of life and slow the disease’s progression.

In healthy dogs, the kidneys act as filters to excrete the body’s toxic waste products. They concentrate and eliminate the waste in urine and then return water and salts to the body to maintain normal hydration and electrolyte balance. In most cases of chronic renal failure, the kidneys simply “wear out” as part of the aging process, drastically reducing their ability to filter these wastes from the blood. Most dogs, however, only show signs of renal failure when 70 to 75 percent of their kidney function has been lost.

The result is a vicious cycle. A dog’s kidneys become less effective at excreting his body’s wastes and less effective at retaining water, producing large quantities of very dilute (poorly concentrated) urine and building up toxins in his bloodstream. To compensate for the increased fluid loss in his urine, he’ll drink more and more water.

Two of the earliest and most easily recognizable signs of kidney failure are increased thirst (polydipsia) and increased urination (polyuria). Other signs include the need to urinate at night (nocturia), loss of appetite, weight loss, bad breath, oral ulcers, pale gums, weakness, poor hair coat, vomiting, blood in his vomit, diarrhea, black, tarry stool, and behavioral changes. These symptoms tend to worsen as the disease progresses.

If your dog exhibits any or all of these signs, see your vet immediately. A correct diagnosis of renal failure requires the following: blood tests to determine the levels of two waste products, urea and creatinine, normally excreted in the urine (elevated concentrations suggest kidney failure), and a urinalysis to measure your dog’s urine-specific gravity (very dilute urine helps confirm the diagnosis).

Once a diagnosis of chronic kidney failure has been made, it’s crucial to provide your dog with round-the-clock access to fresh, clean water -- mainly to prevent dehydration due to the large amount of water passing out of his body -- and put him on a diet high in moisture, with a reduced amount of high-quality protein and a low phosphorus content. You must also carefully and consistently monitor the amount of food and water he consumes each day, and weigh him at least once a week to insure that he’s getting enough calories to maintain his weight and enough water to maintain the proper levels of hydration in his body.

Many dogs benefit from the administration of fluids under their skin. Subcutaneous (SQ) fluids dramatically increase daily water consumption and help keep their kidneys functioning as efficiently as possible. Your vet or veterinary technician will teach you how to administer these fluids to your dog at home, and while it may sound difficult, most people find the procedure easy and most dogs tolerate it well.

Potassium is often added either to the SQ fluids or to your dog’s diet to safeguard against muscle weakness and heart rhythm disturbances that result from low electrolyte levels. In some cases, IV fluids may also be required.

Because hypertension is a common and dangerous complication of chronic renal failure, your dog’s blood pressure should be closely monitored to help prevent further damage to his kidneys. Left untreated, high blood pressure not only accelerates the progression of the disease but can also damage his retinas, resulting in sudden blindness. And so, certain medications may be added to his regime.

The success of your dog’s treatment for chronic kidney failure depends then, in large part, on you. Your reward for carefully monitoring his diet, water intake and blood pressure, and administering his medications will be an improved quality of life for him and the possibility of a longer, loving future together.