How is Kidney Failure in Pets Diagnosed?

Mary McMahon

Chronic renal failure is common among older pets, and there are two major diagnostic tools which are used to identify it: blood testing, and a urine sample. Renal failure is also known as kidney failure, and older animals should be regularly tested for early signs of kidney failure so that the issue can addressed. Usually, the onset of kidney failure is slow, and often difficult for pet owners to identify. In cases of acute kidney failure such as that caused by ingestion of toxins like antifreeze and poison, the disease appears very rapidly, and in both cases, kidney failure is difficult to treat once the animal starts to display symptoms.

A veterinarian can help diagnose kidney failure in a pet.
A veterinarian can help diagnose kidney failure in a pet.

The kidneys serve as filters for the body, and also regulate the balance of salts in the body. When the function of the kidneys is disrupted, toxins will start to build up in the blood stream. These toxins can weaken the body, leading to bacterial infection of other organs. Commonly, the first sign of kidney failure which pet owners notice is an increased tendency to drink water, combined with copious urination. The animal is drinking more water because the higher concentration of toxins in the blood fools the brain into thinking that not enough water is being ingested. However, the toxins are not flushed with the increased water, because the kidneys are not functioning properly. Other signs of kidney failure include lethargy, decreased appetite, depression, and muscle weakness.

A urine sample is taken when kidney failure is suspected.
A urine sample is taken when kidney failure is suspected.

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If kidney failure is suspected, a blood sample is taken along with a urine sample. Both samples must be analyzed for an accurate diagnosis. The urine is tested for blood area nitrogen, urea, and creatinine, and the concentration of the urine is also measured. Dilute urine with abnormal levels of these substances is a sign of kidney failure. If the blood test reveals high levels of metabolic toxins, the veterinarian can be fairly certain that the animal is suffering from kidney failure, and treatment options can be discussed.

In most cases, kidney failure is irreversible. Treatments can help to slow the process, but not to stop it altogether, unless it has been caused by a bacterial infection. Some medications can be used to control it, along with intravenous administration of fluids and dialysis. Some veterinary hospitals may remove a diseased kidney, and specialized hospitals offer kidney transplants. Changes in the animal's diet may also help. Animals with chronic kidney failure may have several years of a contented life if the disease is caught early.

Vet inspecting a cat.
Vet inspecting a cat.

Discussion Comments


In an older dog, if the kidneys are worn out there is not much that can be done to save the dog.

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