A cat’s kidneys have several important jobs. Their main role is to filter waste products from the body, but they also regulate fluids and minerals, help maintain blood pressure, and support red blood cell production.
You might hear terms like chronic renal failure (CRF), chronic kidney disease (CKD), or renal insufficiency. They all refer to the same long-term condition: a gradual decline in kidney function.
CKD progresses slowly over time. Cornell University notes that it’s one of the most common diseases in older cats, affecting up to 40% of cats over age 10 and as many as 80% over age 15. There’s no cure, but with the right management at home and veterinary support, progression can often be slowed. Many cats maintain a good quality of life for a long time after diagnosis.
Exactly how kidney disease begins is hard to pin down. When veterinarians look at affected kidneys under a microscope, they often find inflammation and scarring. But that’s the end result, not the beginning. Many different things might contribute, such as repeated urinary tract infections, blockages, viral or bacterial infections, lymphoma, amyloidosis (abnormal protein deposits), or inherited conditions in certain breeds. Age remains the most consistent risk factor. There’s also some discussion about body condition, increased thirst and urination (PU/PD), and hydration status playing a role in detecting or predicting CKD.
Most major organizations recommend routine veterinary checks every three to six months for older cats. That’s how many cases are caught, through bloodwork and urine tests during those visits. Because diagnosing CKD relies heavily on observing changes in lab values over time, having baseline data is extremely valuable.
There isn’t a single test that definitively measures how well the kidneys are working. Instead, veterinarians use a combination of findings. An increased creatinine level combined with urine that is less concentrated than it should be (low USG) often suggests reduced kidney function. Blood Urea Nitrogen (BUN) and phosphorus are also considered alongside the rest of the blood panel. Still, interpretation isn’t always straightforward. A saying we have on the Feline Diabetes Message Board that applies here, “Every Cat is Different” (ECID).
CKD is categorized into four stages. Staging is based primarily on creatinine ranges and clinical signs. Stage 1 is below 1.6 mg/dL (140 µmol/L), Stage 2 ranges from 1.6 to 2.8 mg/dL (140–250 µmol/L), Stage 3 ranges from 2.8 to 5.0 mg/dL (250–440 µmol/L), and Stage 4 is anything above 5.0 mg/dL (440 µmol/L). Staging matters because prognosis and treatment recommendations differ based on where a cat falls. There are also substaging components based on proteinuria (protein in urine) and blood pressure.
Managing CKD focuses on quality of life (QoL) and longevity. Our furry companions really did draw the short straw when it comes to kidney resilience, but there is a lot we can do to support them.
Hydration is king. Kidneys need enough fluid for proper filtration. Ensuring your cat has easy access to fresh water, using fountains, adding flavor to water, or feeding wet food can help. In more advanced stages, additional hydration methods like feeding tubes or subcutaneous fluids may be needed. These are more involved and should always be guided by your veterinarian with your cat’s IRIS stage.
Diet is another major piece of the puzzle, a second king or queen. Renal diets generally restrict phosphorus and sometimes protein. There’s debate in the research about how much protein restriction is appropriate. Recent information suggests being cautious about restricting protein too much, since that can cause or worsen muscle loss. There is stronger evidence supporting the benefit of lowering phosphorus to improve longevity. Not all cats like the taste of renal diets, especially if they already feel mildly nauseous. Phosphate binders provide another way to reduce phosphorus, but too-low phosphorus is also harmful, so binders should only be used with careful veterinary guidance and monitoring.
Monitoring blood pressure is another important part of managing CKD. High blood pressure isn’t necessarily an independent cause of CKD, but it can damage the kidneys, eyes, and heart. Depending on blood pressure readings, the ISFM guidelines outline specific actions a vet may recommend.
Nausea, vomiting, and reduced appetite are extremely common in chronic kidney disease. This is caused by toxin buildup that healthy kidneys would normally clear. Poor appetite then spirals into problems with hydration, protein intake, and general energy. From both the ISFM guidelines and years of experience on the Feline Diabetes message board, ondansetron and maropitant (Cerenia) are frequently used for nausea and vomiting, while mirtazapine helps stimulate appetite. A general rule of thumb from the FDMB is to treat nausea before stimulating appetite, which makes sense. If you as a human were nauseous and hungry at the same time, forcing yourself to eat wouldn’t feel good either.
Often CKD cats are older and have other conditions present. One thing to be mindful of is medication safety as it relates to CKD progression. Some drugs used for unrelated conditions can complicate CKD, especially medications that are cleared through the kidneys. According to ISFM, drugs metabolized by the liver are often preferred in CKD cats, but this should always be discussed with your vet.
Hyperthyroidism is another common condition that interacts with CKD. It can mask kidney disease or contribute to its progression, and treating hyperthyroidism in a CKD cat requires careful medication choices.
The main source I analyzed for this information was the guidelines from the International Society of Feline Medicine (ISFM). They are a global organization dedicated to improving the health and wellbeing of cats through research, education, and veterinary guidelines. Their guidelines are evidence based and create practical recommendations for veterinarians and caregivers. Their CKD guidelines seem to be the go-to resource for vets and caregivers managing a CKD cat.
Sources:
ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease
Cornell University - Chronic Kidney Disease
PetMD - Kidney Disease in Cats: Signs, Causes, and Treatment
You might hear terms like chronic renal failure (CRF), chronic kidney disease (CKD), or renal insufficiency. They all refer to the same long-term condition: a gradual decline in kidney function.
CKD progresses slowly over time. Cornell University notes that it’s one of the most common diseases in older cats, affecting up to 40% of cats over age 10 and as many as 80% over age 15. There’s no cure, but with the right management at home and veterinary support, progression can often be slowed. Many cats maintain a good quality of life for a long time after diagnosis.
Exactly how kidney disease begins is hard to pin down. When veterinarians look at affected kidneys under a microscope, they often find inflammation and scarring. But that’s the end result, not the beginning. Many different things might contribute, such as repeated urinary tract infections, blockages, viral or bacterial infections, lymphoma, amyloidosis (abnormal protein deposits), or inherited conditions in certain breeds. Age remains the most consistent risk factor. There’s also some discussion about body condition, increased thirst and urination (PU/PD), and hydration status playing a role in detecting or predicting CKD.
Most major organizations recommend routine veterinary checks every three to six months for older cats. That’s how many cases are caught, through bloodwork and urine tests during those visits. Because diagnosing CKD relies heavily on observing changes in lab values over time, having baseline data is extremely valuable.
There isn’t a single test that definitively measures how well the kidneys are working. Instead, veterinarians use a combination of findings. An increased creatinine level combined with urine that is less concentrated than it should be (low USG) often suggests reduced kidney function. Blood Urea Nitrogen (BUN) and phosphorus are also considered alongside the rest of the blood panel. Still, interpretation isn’t always straightforward. A saying we have on the Feline Diabetes Message Board that applies here, “Every Cat is Different” (ECID).
CKD is categorized into four stages. Staging is based primarily on creatinine ranges and clinical signs. Stage 1 is below 1.6 mg/dL (140 µmol/L), Stage 2 ranges from 1.6 to 2.8 mg/dL (140–250 µmol/L), Stage 3 ranges from 2.8 to 5.0 mg/dL (250–440 µmol/L), and Stage 4 is anything above 5.0 mg/dL (440 µmol/L). Staging matters because prognosis and treatment recommendations differ based on where a cat falls. There are also substaging components based on proteinuria (protein in urine) and blood pressure.
Managing CKD focuses on quality of life (QoL) and longevity. Our furry companions really did draw the short straw when it comes to kidney resilience, but there is a lot we can do to support them.
Hydration is king. Kidneys need enough fluid for proper filtration. Ensuring your cat has easy access to fresh water, using fountains, adding flavor to water, or feeding wet food can help. In more advanced stages, additional hydration methods like feeding tubes or subcutaneous fluids may be needed. These are more involved and should always be guided by your veterinarian with your cat’s IRIS stage.
Diet is another major piece of the puzzle, a second king or queen. Renal diets generally restrict phosphorus and sometimes protein. There’s debate in the research about how much protein restriction is appropriate. Recent information suggests being cautious about restricting protein too much, since that can cause or worsen muscle loss. There is stronger evidence supporting the benefit of lowering phosphorus to improve longevity. Not all cats like the taste of renal diets, especially if they already feel mildly nauseous. Phosphate binders provide another way to reduce phosphorus, but too-low phosphorus is also harmful, so binders should only be used with careful veterinary guidance and monitoring.
Monitoring blood pressure is another important part of managing CKD. High blood pressure isn’t necessarily an independent cause of CKD, but it can damage the kidneys, eyes, and heart. Depending on blood pressure readings, the ISFM guidelines outline specific actions a vet may recommend.
Nausea, vomiting, and reduced appetite are extremely common in chronic kidney disease. This is caused by toxin buildup that healthy kidneys would normally clear. Poor appetite then spirals into problems with hydration, protein intake, and general energy. From both the ISFM guidelines and years of experience on the Feline Diabetes message board, ondansetron and maropitant (Cerenia) are frequently used for nausea and vomiting, while mirtazapine helps stimulate appetite. A general rule of thumb from the FDMB is to treat nausea before stimulating appetite, which makes sense. If you as a human were nauseous and hungry at the same time, forcing yourself to eat wouldn’t feel good either.
Often CKD cats are older and have other conditions present. One thing to be mindful of is medication safety as it relates to CKD progression. Some drugs used for unrelated conditions can complicate CKD, especially medications that are cleared through the kidneys. According to ISFM, drugs metabolized by the liver are often preferred in CKD cats, but this should always be discussed with your vet.
Hyperthyroidism is another common condition that interacts with CKD. It can mask kidney disease or contribute to its progression, and treating hyperthyroidism in a CKD cat requires careful medication choices.
The main source I analyzed for this information was the guidelines from the International Society of Feline Medicine (ISFM). They are a global organization dedicated to improving the health and wellbeing of cats through research, education, and veterinary guidelines. Their guidelines are evidence based and create practical recommendations for veterinarians and caregivers. Their CKD guidelines seem to be the go-to resource for vets and caregivers managing a CKD cat.
Sources:
ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease
Cornell University - Chronic Kidney Disease
PetMD - Kidney Disease in Cats: Signs, Causes, and Treatment