What is Kidney Disease?
Kidney disease in cats is the progressive and irreversible loss of kidney function. Chronic kidney disease (CKD) is the most common type of kidney disease diagnosed in cats. Kidney disease is determined to be chronic when the disease has been present for at least three months.
Chronic kidney disease is also known as chronic kidney or renal failure (CRF) or chronic kidney or renal insufficiency (CKI). As the kidneys are damaged and lose function, the body retains toxins in the bloodstream. Red blood cell production and hormones are affected, the cat’s drinking and urinary habits change, and blood pressure increases. There are also gastrointestinal side effects and many different electrolytes, mineral, and protein abnormalities in the blood and urine. The kidneys can’t keep up with their job, and as a result, many bad things happen.
What are the Causes of Kidney Disease
There are many causes of kidney disease in cats. Some common ones are:
- Toxins: Certain toxic medications, plants, and other toxins.
- Inflammation: Conditions such as pyelonephritis (a bacterial infection of the renal pelvis) and glomerulonephritis (a specific type of kidney disease) involve inflammation and infection in the kidneys.
- Congenital and Inherited Disorders: Examples are polycystic kidney disease and various kidney malformations (dysplasias) such as hypoplasia.
- Cancer: A common cancer affecting the kidneys is lymphoma.
- Viral Infections: Retroviruses such as Feline Leukemia Virus and Feline Immunodeficiency Virus and Feline Infectious Peritonitis Virus.
- Bacterial Infections: Pyelonephritis and Leptospirosis are bacterial infections that can affect a cat’s kidneys.
- Obstructive Disease: Upper urinary tract obstructions such as kidney stones or stones in the ureters can cause kidney disease.
- Immune-Mediated Disease
- Various Metabolic and Endocrine Disorders
- Idiopathic: This refers to an unknown cause.
What are the Symptoms of Kidney Disease?
The clinical signs and manifestations of kidney disease depend on how advanced the disease is and how much kidney function is lost. Initial symptoms are subtle and will develop and progress over time. Typically, owners will see the following signs:
- Polydipsia: Drinking more than normal
- Polyuria: Urinating more than normal
- Anorexia: Loss of appetite
- Weight Loss
- Dehydration: Despite drinking more
- Vomiting and Nausea
- Muscle Weakness and Loss
- Halitosis: Bad Breath
- Ulcers in the Mouth
- Pale Gums Due to Anemia (Low Red Blood Cells)
- Lethargy: Decreased Energy and Increased Weakness
- Hypertension: High Blood Pressure
How Is Kidney Disease Diagnosed?
If kidney disease is suspected in your cat, they should be taken to see a veterinarian right away. A veterinarian will perform a physical examination as well as blood and urine tests and abdominal imaging. Two kidney values are measured in the blood, blood urea nitrogen (BUN) and creatinine (CRE). With kidney failure, toxins are built up in the blood, causing these values to increase. This is known as azotemia.
Another blood test, symmetric dimethylarginine (SDMA), is also useful for determining kidney function. Consequences of kidney disease include changes in electrolytes such as potassium, minerals such as phosphorus, and blood cells such as red blood cells. These values are also monitored with blood tests. Urine tests show signs of kidney disease through poorly concentrated urine, protein loss in the urine, bacterial infections, and crystal or stone formation.
Imaging of the abdomen with radiographs (X-rays) and ultrasound help determine the size, structure, and other anomalies associated with kidney disease.
How Is Kidney Disease Treated?
There is no targeted treatment or cure for chronic kidney disease. The disease doesn’t just develop overnight. It is a progressive and chronic loss of kidney function, so once it is gone, we can’t get it back. If there are specific causes such as an infection or inflammation, treatment should be started for these conditions. Typically, even once these conditions are treated, the kidneys are left permanently damaged and have decreased function. This leaves symptomatic treatment and supportive care as the methods to manage and slow the progression of kidney disease.
Making sure your cat is hydrated, eating, and pain-free are key factors in supportive care. Hydration is an essential aspect of supportive therapy. By increasing fluid intake in CKD patients, the kidneys get flushed of toxins, the cat feels better, and sometimes eats better too. The goal should be maintaining a good quality of life.
Other supportive care aspects vary from patient to patient and may include treatment for anemia, hypertension, protein in the urine, low potassium, high phosphorus, and gastrointestinal complications such as nausea, vomiting, diarrhea, anorexia, and weight loss.
What to Feed Cats with Kidney Disease?
Diet therapy is highly recommended for cats with kidney disease. Therapy is typically through prescription diets with decreased amounts of protein, phosphorus, sodium, and increased fiber, calories, and antioxidants. While prescription diets are important, the most important thing is to make sure the cat eats.
How is Kidney Disease Prevented in Cats?
Unfortunately, there is no way to prevent kidney disease. The key is to catch it early through regular physical exams and diagnostic screening.
What is the Life Expectancy for Cats with Kidney Disease?
Kidney disease is most commonly diagnosed in older cats, typically over ten years of age. The life expectancy for cats with kidney disease varies greatly because it depends on certain factors like:
- What the underlying cause is
- How quickly the disease progresses
- How well the cat responds to supportive therapy
- Other consequences of kidney disease your cat is suffering from
- What stage of kidney failure the cat is in
Cats can live for weeks, months, and even years with kidney disease.
When Should You Euthanize A Cat with Kidney Disease?
Determining when to euthanize a cat is a personal decision between the cat owner and veterinarian. The cat’s quality of life is the most important factor in deciding when to euthanize.
A good quality of life is typically when the cat is comfortable and pain-free, eating and drinking on its own, and their symptoms and secondary conditions related to kidney failure are under control. Poor quality of life occurs when the cat is uncomfortable or in pain, not eating or drinking on its own, urinating and defecating on itself or not making it to the litter box, and suffering from unmanaged side effects of kidney disease. When the bad days outweigh the good days, it might be time to talk to your veterinarian about euthanasia.
Dr. Amanda Jondle is a veterinarian who practices small animal medicine and surgery. Growing up on a small farm, she knew from a very young age that she wanted to work with animals and started spending time at a local vet clinic at 11 years old. In addition to working full time at an animal hospital, she now enjoys helping pets and educating clients through writing and editing articles to inform pet owners on how to best care for their pets. She and her husband currently have 4 rescue dogs and 3 cats of their own and are often fostering pets with health issues until they find their forever homes.