Is your older cat suddenly drinking and urinating a lot? – Important symptoms of kidney failure in cats

It often starts subtly. You may notice that the water bowl needs to be refilled more often than before, or that the litter in the litter box forms larger and heavier clumps. Many cat owners interpret these changes as natural signs of aging or believe it is positive that the cat drinks a lot. In veterinary medicine, however, we know that a sudden increase in thirst and urination in a middle-aged or older cat is often the first clear sign that kidney function is failing. Chronic kidney disease (CKD) is one of the most common diagnoses in older cats.

The condition requires prompt action to ensure the cat maintains its quality of life. Early detection makes it possible to diagnose and provide the right support before kidney function has deteriorated too much. Below is an overview of what happens in the cat’s body when the kidneys no longer function optimally and why early signs require attention. By learning to interpret your cat’s signals, you and your veterinarian can create a safe everyday life for your cat.

What does kidney failure in cats mean and how is the body affected?

The kidneys function as the cat’s filtration system. Their task is to filter the blood of waste products formed during protein breakdown, as well as regulate fluid balance and mineral levels. In kidney failure, the organs have lost a significant portion of their ability to perform these vital tasks. There are two main types of kidney failure: acute and chronic. The acute form occurs suddenly, often due to poisoning from, for example, lilies or antifreeze, or because of an infection. Chronic kidney failure, on the other hand, is a progressive process that develops over months or years. One challenge with chronic kidney disease is the kidneys’ large reserve capacity. The cat may appear healthy even though a large part of the kidney tissue has stopped functioning. Symptoms often become apparent only when about 66–75% of the function is lost. When filtration does not work, waste products such as urea and creatinine remain in the blood. This causes nausea and reduced appetite. In addition, the kidneys lose the ability to concentrate urine. Instead of conserving water, they allow fluid to pass into the bladder, which explains the large amounts of urine in the litter box.

Early warning signs – Why increased thirst is a serious symptom

The most common sign of kidney failure is medically referred to as polydipsia and polyuria – increased thirst and urination. It is a common misconception that the cat urinates a lot because it drinks a lot. In kidney failure, the opposite is true. The cat loses enormous amounts of fluid through urine because the kidneys cannot retain water. To avoid dehydration, the cat is forced to drink more as compensation. Other early signs to watch for: Veterinary studies show that weight loss is often the very first sign of kidney problems. This is due to protein loss via urine and nausea reducing energy intake. If your cat suddenly drinks from unusual sources, such as watering cans or taps, you should schedule an examination. Early diagnosis provides the best conditions to slow the progression with an adapted diet.

The path to diagnosis – How the veterinarian determines kidney disease

If kidney failure is suspected, the diagnosis is made through a clinical examination, blood tests, and urinalysis. In addition to creatinine levels, sensitive tests such as SDMA are now used. These tests detect kidney failure in cats much earlier than traditional methods, enabling intervention at an early stage. The urine sample is central for measuring urine concentration. By checking specific gravity, the veterinarian can determine whether the kidneys can conserve water. The presence of protein in the urine is also an indicator of damage. Blood pressure is often measured as well, as high blood pressure is a common consequence of kidney problems that requires treatment.

The role of diet in the cat’s well-being

The right diet is the most important factor in treatment. A tailored renal diet reduces the burden on the organs and slows the progression of the disease. A veterinary renal diet differs from regular food in three factors: Reducing phosphorus is crucial. When the kidneys cannot filter out phosphorus, it accumulates in the blood, worsening the disease and nausea. The protein in renal diets is of high quality but in limited amounts to reduce waste products while preserving muscle mass. It is also important to increase the cat’s fluid intake. Wet food is often better than dry food for cats with kidney disease because the extra fluid counteracts dehydration. In the range of products for cats there are several options that support kidney health. Kidney failure requires attention, but with the right diet and veterinary care, many cats can live a good life for a long time despite the diagnosis. By acting on signs such as thirst and weight loss, you give your cat good conditions. Small adjustments in daily life make a big difference for well-being.