When we recently reviewed our top performing blogposts, we found something interesting: the oldest post and the only top post specifically about cats focused on chronic kidney disease.
Fourteen years later, the topic remains just as relevant. With World Kidney Day on March 12th highlighting Kidney Health for All, it’s worth remembering that kidney health matters for our feline family members too.
A diagnosis of kidney disease in your cat can sound frightening. But in many cases, especially when detected early, feline chronic kidney disease can be managed for years, allowing cats to maintain an excellent quality of life.
Annual Testing Helps Detect Kidney Disease Early
Early detection is key.
The American Animal Hospital Association Feline Life Stage Guidelines suggest annual blood testing for cats less than 7 years of age and recommends it for cats over 7 years of age. These tests include an assessment of kidney function, creatinine and blood urea nitrogen (BUN). This helps veterinarians evaluate kidney health before obvious clinical signs develop. Because cats are masters at hiding illness, laboratory screening often identifies chronic kidney disease before owners notice changes at home.
Understanding a Diagnosis of Chronic Kidney Disease in Cats
Estimates suggest 1-3% of cats will develop kidney disease during their lifetime, and one in twelve geriatric cats has kidney disease.
To the typical cat owner, a diagnosis of kidney disease sounds ominous—but it’s not always as bad as it sounds.
Take for example my nephew cat, BeeDee. He had a rough start in life, abandoned as a kitten at The Schwarzman Animal Medical Center following a head trauma incident. My sister adopted him and he lived a good life, 21 years, to be exact, despite a diagnosis of chronic kidney disease at age 18.
The diagnosis of chronic kidney disease in a cat like BeeDee is based on:
Elevation in creatinine
Evaluation of urine specific gravity
Urine protein levels
Blood pressure.
Some laboratories also measure symmetric dimethylarginine (SDMA), believed to be an early marker of kidney disease.
In chronic kidney disease:
Urine is often isosthenuric, meaning it is neither concentrated nor dilute because the impaired kidneys no longer can concentrate or dilute the urine.
Creatinine and BUN may also be elevated in disorders other than chronic kidney disease, such as a kidney infection or dehydration, which is why multiple tests are essential to confirm a CKD diagnosis.
Bringing a urine sample to your cat’s annual examination will win you a gold star from your veterinarian, as it allows for a more complete assessment of kidney health.
If you’re unsure how to collect feline urine, here are some suggestions.
IRIS Staging: How Chronic Kidney Disease in Cats is Classified
The International Renal Interest Society (IRIS) has guidelines to grade the severity of chronic kidney disease in cats based on blood and urine tests, plus blood pressure. These guidelines rank kidney disease from stage I to stage IV, with stage IV being the most severe.
Since up to 20% of cats with CKD have hypertension or high blood pressure, your cat’s veterinarian will recommend blood pressure monitoring if your cat has CKD. Blood pressure, urine protein level and organ damage from hypertension all play a role in IRIS staging. As your cat’s IRIS stage increases, so does the need for treatment – but staging helps veterinarians tailor their medical management appropriately.
A Newer Marker: Fibroblast Growth Factor 23 (FG23)
Nutritional management is a cornerstone of CKD treatment. Cats with CKD are often fed a diet restricted in phosphorus to decrease the kidneys’ workload.
Now we have a test to determine if phosphorus is starting to accumulate in the body, before the phosphorous blood test starts to climb. Elevated levels of fibroblast growth factor 23, or FG23, in cats with a normal level of phosphorus in the blood indicates it’s time to start feeding a restricted phosphorus diet. Preventing excessive phosphorus accumulation is important to keeping your cat with CKD feeling well.
What Survival Data Tell Us
Average survival times:
Stage IIb (creatinine >2.3 mg/dL): over 1,000 days
Stage III (>2.8 mg/dL): nearly 800 days
Stage IV (>5 mg/dL): approximately 100 days
These numbers underscore an important point: lower IRIS stages are associated with significantly longer survival times. Early diagnosis truly matters.
The Takeaway: Don’t Assume the Worst
If your cat is diagnosed with low IRIS stage chronic kidney disease, try not to worry. Treatment can help keep your cat around for years to come. I can’t guarantee your cat will do as well as my nephew cat and live to the ripe old age of 21 – but with early detection and appropriate management, a diagnosis of chronic kidney disease does not automatically mean the worst.