Kidney Disease in Cats

What do the kidneys do?

The kidneys filter waste from the blood into the urine, conserve water, balance minerals such as potassium and phosphorus, help regulate blood pressure, and produce a hormone that drives red blood cell production. When they fail, waste products build up in the bloodstream and every one of those jobs suffers.

What is chronic kidney disease?

Chronic kidney disease (CKD) is the gradual, permanent loss of kidney function over months to years. It is one of the most common diseases of older cats, affecting roughly a third of cats over ten and more than half of very elderly cats. The kidneys have a large reserve, so signs do not appear until about two-thirds of the function is gone, which is why routine screening of senior cats matters.

Acute kidney injury is different: a sudden loss of function from a poison such as lily plants or antifreeze, a urinary blockage, or a severe infection. It is an emergency, and if treated quickly some cats recover.

What are the signs?

• Drinking more and urinating more, often the first thing owners notice
• Weight loss and loss of muscle along the back
• Reduced appetite or pickiness
• Vomiting, especially in the morning
• Bad breath, drooling, or mouth ulcers
• A dull, unkempt coat and lethargy
• Weakness or a plantigrade stance from low potassium
• Sudden blindness from high blood pressure

How is kidney disease diagnosed?

Blood tests measure creatinine, urea, and SDMA, a newer marker that rises earlier than the others. A urine test checks how well the kidneys concentrate urine and looks for protein and infection. Blood pressure is measured because hypertension is common and damages the kidneys further. These results place the cat in one of four stages, which guides treatment and gives a realistic outlook. An ultrasound is sometimes added to look for stones, infection, or a tumor.

How is it treated?

Chronic kidney disease cannot be cured, but its progression can be slowed and most cats feel much better with treatment tailored to their stage:

• Kidney diet. Prescription renal diets are lower in phosphorus and have moderate, high-quality protein. Switching to one is the single most effective step and has been shown to extend life. Introduce it gradually, and never let a cat go hungry over a diet change.
• Hydration. Encourage drinking with fountains, multiple water bowls, and canned food. Many cats do well with fluids given under the skin at home a few times a week; we teach you how.
• Phosphorus binders when diet alone does not control phosphorus.
• Blood pressure medication for cats with hypertension.
• Potassium supplements, anti-nausea drugs, appetite stimulants, and treatment of anemia as they are needed.
• Treating urinary tract infections, which are common in cats with dilute urine.

What is the outlook?

It depends on the stage at diagnosis and how the cat responds. Cats found in the early stages often live comfortably for several years. Regular rechecks, usually every three to six months, let us adjust treatment as the disease changes. Our Cat Chronic Disease Management and Cat Senior Care pages describe how we support cats through this.

Can it be prevented?

The most common form cannot be prevented, but it can be caught early. Yearly blood and urine screening for cats over seven, a fresh-water habit, keeping lilies out of the house entirely, and prompt treatment of urinary problems all help protect the kidneys.

See also: Kidney Disease in Dogs