What are the symptoms of kidney disease in cats? A veterinarian explains the symptoms and treatments in detail.

A few years ago, a substance related to kidney disease in cats was identified and reported in the media.

It became known not only to cat owners but also to non-cat owners that cats are prone to kidney disease. Chronic kidney disease is common in older cats, affecting 30-40% of cats over 7 years old and 80% of cats over 15 years old, making kidney disease the leading cause of death in cats.

This time, we will explain cat kidney disease.

What is Feline Kidney Disease?

There are two types of feline kidney disease: acute kidney disease (acute renal failure) and chronic kidney disease (chronic renal failure).

Acute Kidney Disease

Acute kidney disease is a condition where blood does not circulate to the kidneys due to hemorrhage or low blood pressure, preventing waste products from being excreted in the urine. The main cause is reduced blood circulation to the kidneys due to hemorrhage or surgery. It can also be caused by toxins, drugs, or poisonous plants that affect the kidneys. Typical examples include poisoning from ethylene glycol found in old antifreeze or arsenic in rat poison.

Chronic Kidney Disease

Chronic kidney disease occurs when the kidneys are damaged for several months or more. Chronic renal failure progresses gradually and cannot be cured even with treatment, eventually leading to end-stage renal failure or uremia.

Kidney function is evaluated by blood urea nitrogen and creatinine levels in blood tests, but these values only show abnormalities when about 75% of kidney function has been lost. Recently, SDMA has emerged as a new indicator for kidney function. SDMA shows abnormalities when about 40% of kidney function is lost, making it a promising indicator for earlier diagnosis of kidney disease.

Chronic kidney disease is common in older cats over 7 years old and is the leading cause of death. It is also believed that kidney function gradually declines from around 5 years of age. The main cause had been unclear for many years, but it was recently discovered that a substance called "AIM" is involved in kidney aging, and that AIM does not function in cats. AIM is therefore expected to become a potential therapeutic drug for feline kidney disease.

Abyssinian and Persian cats are genetically prone to kidney disease. Polycystic kidney disease is also common in breeds such as Persian and Exotic Shorthair cats, making them more susceptible to chronic kidney disease. Furthermore, prolonged urinary stones or bladder stones can also lead to chronic kidney disease.

What are the Symptoms of Kidney Disease in Cats?

We will explain the symptoms of acute kidney disease and chronic kidney disease separately.

Symptoms of Acute Kidney Disease

Acute kidney disease causes a sudden loss of energy, loss of appetite, vomiting, and diarrhea. Urine output also decreases or stops altogether. Hypothermia is also common.

Symptoms of Chronic Kidney Disease

Chronic kidney disease has four stages, and the symptoms vary at each stage.

Early Stage (Stage I)

There are no symptoms in the early stage. This is a period when no abnormalities are found in blood or urine tests.

Middle Stage (Stage II)

Mild loss of appetite, weight loss, increased thirst, and increased urination begin to occur. Urine specific gravity (concentration of urine) starts to decrease in urinalysis, resulting in dilute urine.

In blood tests, creatinine and urea nitrogen levels are normal to slightly elevated.

Late Stage (Stage III)

In the late stage, blood urea nitrogen and creatinine levels rise. Kidney function is significantly impaired, resulting in dilute urine.

Appetite decreases, and weight loss occurs. Vomiting also begins. Anemia occurs due to a decrease in the hematopoietic hormone (erythropoietin) produced by the kidneys. Even if the cat drinks water, it is not absorbed into the body and is excreted as urine, leading to dehydration. If you pinch the skin on the back, it will be slow to return, which is a sign of dehydration.

Many elderly cats examined at veterinary hospitals are diagnosed with chronic kidney disease stages II and III.

End Stage (Stage IV)

The end stage, also known as the uremic stage, is when symptoms of uremia appear. There is a complete loss of appetite and frequent vomiting. The cat becomes very thin and severely dehydrated. A urine odor is often noticeable from the entire body. Uremia can also cause seizures. Anemia progresses, and the inside of the mouth becomes pale. Stomatitis also tends to occur.

Once the end stage is reached, treatment offers little hope of extending life.

Can Feline Kidney Disease be Cured? What are the Treatment Options?

Treatment methods differ for acute kidney disease and chronic kidney disease, so we will explain each separately.

Treatment for Acute Kidney Disease

Acute kidney disease has a very high chance of improvement if the cause is resolved. Therefore, it is important to thoroughly investigate and identify the cause.

In cases of acute kidney disease, severe dehydration can occur. Intravenous fluids are administered rapidly to correct dehydration. Since the body's ion balance is often disrupted, ion balance correction is also performed. Antiemetics are used for vomiting in acute kidney disease.

Dialysis (peritoneal dialysis) may be performed in facilities that can provide it.

Treatment for Chronic Kidney Disease

Unfortunately, there is no definitive cure for chronic kidney disease at this time. All treatments aim to slow the progression of the disease or manage its symptoms.

Treatment for chronic kidney disease varies by stage.

In the early stages, dietary therapy for kidney disease is implemented.

In the middle stage, dietary therapy remains the main treatment. Additionally, antihypertensive drugs may be used to suppress the progression of kidney disease. Supplements with antioxidant properties are also considered effective.

In the late stage, appetite decreases due to nausea and other symptoms. While dietary therapy remains the basis, fluid therapy also becomes necessary in the late stage. Fluid therapy is generally performed daily. Intravenous fluids improve dehydration, and antiemetics are also used. In cases of severe anemia, hematopoietic agents may be administered.

In the end stage, fluid therapy is the main treatment. If dialysis is available, it is performed. Due to loss of appetite, nutritional support via catheter becomes necessary. As anemia becomes quite advanced, blood transfusions may also be performed.

Summary

Kidney disease can be fatal for cats. Especially in the case of chronic kidney disease, there is no established cure, and the main goal is to slow its progression as much as possible.

Chronic kidney disease often presents with almost no symptoms in its early stages and is usually discovered incidentally during health check-ups. By the time symptoms appear and the cat is taken to the hospital, the disease is often quite advanced.

To detect kidney disease early, annual to semi-annual health check-ups and keen observation by the owner are crucial.