Chronic kidney disease in cats

Chronic kidney disease (CKD) is the progressive, irreversible deterioration of kidney function. Veterinarians estimate that up to half of cats over the age of 15 will develop renal failure, making CKD a leading cause of death in older cats. However, CKD commonly develops in much younger cats as well, so regular vet exams are important to monitor your cat’s kidney function.

Chronic kidney disease (CKD) involves the loss of kidney function over time. The kidneys are the body’s filter and are responsible for:

• Helping maintain fluid balance in the body
• Producing certain hormones
• Regulating electrolytes in the body
• Excreting waste products via urine
• Removing toxins from the blood
• Maintaining normal blood pressure

When the kidneys fail to work properly, waste products and toxins begin to build up in a cat’s body. Although CKD is not curable, appropriate support can improve your cat’s quality of life and slow the disease’s progression. The rate of decline with CKD varies, so your cat may be able to live comfortably for years.

CKD is generally classified into one of four stages based on laboratory tests and clinical signs. But first, here are some terms you should know, since your veterinarian will likely use these terms when discussing the progression of your cat’s kidney failure:

• Blood urea nitrogen (BUN). A cat’s body disposes of the nitrogen components in the food they eat through their urine. While a buildup of nitrogen doesn’t damage the kidneys, it can make your cat feel nauseous and not want to eat.
• Creatinine. Creatinine is a waste product produced through normal muscle cell cycles. The creatinine level in the blood provides a fairly accurate picture of the kidneys’ ability to filter out waste products.
• Phosphorus. Just like BUN, phosphorus is a byproduct of protein digestion. However, increased phosphorus can lead to further kidney damage and predict worsening disease.
• Urine specific gravity. The kidneys are responsible for concentrating urine. If the urine produced by your cat is clear, it likely isn’t concentrated. And, if a cat’s blood is high in waste products, kidney damage is the likely culprit.

The stages of CKD in cats

To stage acute or chronic kidney disease, the IRIS staging system is used. Staging CKD is important for determining the most effective way to slow the disease’s progression and keep your cat comfortable.

Stage one. In this initial stage, the kidneys have lost 65% of their function, but other clinical signs aren’t yet apparent. Though early detection is key to a good outcome, renal disease is rarely diagnosed this early on in cats.

Stage two. In stage two, a cat’s kidney disease has progressed. A test to determine how well their kidneys are working would indicate they have less than 25% of normal function. At this point, you likely won’t see symptoms. However, the kidneys may be struggling to concentrate urine, so your cat may use their litter box more frequently than normal.

Stage three. At this stage, you’ll likely begin to notice signs of illness in your cat, and only 10% of their kidney tissue may still be working.

Stage four. The fourth and final stage of the disease reflects further progression. Signs of illness are so obvious by this point that a CKD diagnosis can sometimes be made by simply looking at a cat. At this point, more than 90% of kidney function has been lost.

The major issue with chronic kidney failure is that symptoms don’t appear until more than half of a cat’s total functioning kidney tissue is lost. By the time the disease has progressed to this point, management can be challenging, though still doable for some kitties.

If your cat is getting older, be on the lookout for these signs of chronic kidney disease:

• Poor appetite. If your cat doesn’t feel well, they won’t want to eat.
• Nausea. As the kidneys fail, toxins and waste byproducts will build up in their body, ultimately making your cat feel nauseous.
• Weight loss. As nausea takes its toll on your cat, their appetite will drop, resulting in weight loss.
• Lethargy. Feeling nauseous can make anyone feel like lying around. Pair nausea with a poor appetite, and your cat won’t have much energy to play and interact. Decreased potassium can also cause muscle weakness and stiffness.
• Increased thirst. Since the kidneys can’t concentrate urine like they used to, your cat will pee more frequently, causing them to become thirstier.
• Increased urination. What goes in must come out. As your cat begins to drink more, they’ll produce more urine as well.
• Vomiting. Your cat can become so nauseous from toxin buildup in their bloodstream that they begin to vomit.
• Poor coat. When you’re sick, do you care what you look like? Neither does a cat with CKD. Grooming and self-care fall to the wayside when a cat is battling nausea, fatigue, dehydration, and excessive urination. Low potassium can also cause a poor haircoat.
• Bad breath. The breath of cats with end-stage disease can smell slightly of ammonia.
• Dehydration. Despite constant drinking, cats with CKD can still become dehydrated due to increased water loss.

👉 An early diagnosis is essential for giving your cat the best prognosis, so head to your vet immediately if you notice any of these signs. 

Many different things can cause kidney damage, and, unfortunately, most can’t be prevented. Risk factors that may predispose your cat to CKD include:

Breed. Certain feline breeds are more likely to develop CKD. If your cat is a Persian, Abyssinian, Siamese, Burmese, Russian blue, Maine coon, or ragdoll, you’ll need to closely monitor their kidney function throughout their life. Familial diseases, such as polycystic kidney diseases, have also been linked to specific breeds, such as the Oriental, British long and shorthair, exotic shorthair, Burmilla, Scottish fold, and Selkirk rex.

Age. Senior animals are most at risk, though some cats can develop CKD at a younger age. If a younger cat develops CKD, it’s likely due to a familial renal disease or untreated acute kidney failure that has become chronic. Older pets often have another age-related disease that plays a part in the development of their CKD.

Underlying conditions. If your cat already has an underlying condition, they may be more likely to develop CKD. Disorders that are associated with CKD include hypercalcemia, heart disease, dental disease, cystitis, urolithiasis, hyperthyroidism, diabetes, and certain infections.

Diet. Some dietary formulations have been associated with the development of CKD in cats. Diets that are low in potassium and high in phosphorus Trusted Source PubMed Central Archive of biomedical and life sciences journal literature. Go to source and protein are the most problematic. Overall, more research is needed to determine how a cat’s diet affects their kidney function.

Drugs. Certain medications used to diagnose or treat conditions have been linked to CKD. Examples include nonsteroidal anti-inflammatories (NSAIDs), aminoglycosides, sulfonamides, polymyxins, amphotericin, chemotherapeutic medications, and certain vaccines.

Injury. Certain diseases that cause acute injuries to the kidneys’ structures can initiate CKD. In addition to familial renal diseases, infectious and inflammatory causes can trigger kidney disease. Mercury toxicity, cancer, and crystalluria can also cause kidney damage.

A trip to your veterinarian is in order if your cat begins to drink and urinate excessively. These signs could indicate a urinary tract infection, diabetes, or kidney disease, but you won’t know without diagnostic testing.

To determine if your cat has CKD, your veterinarian may recommend the following tests:

• Blood work. Cats with kidney disease typically show kidney enzyme elevations in their blood work. Creatinine and BUN levels are often increased as well. Electrolyte levels may be unbalanced, and anemia can also occur.
• SDMA testing. Symmetric dimethylarginine (SDMA) testing may aid in early CKD detection and allow for more accurate staging. This test is generally used alongside BUN and creatinine concentrations to give the most accurate information.
• Blood pressure measurement. Hypertension is a relatively common complication of CKD, so your vet will want to see if your cat has high blood pressure.
• Urinalysis. Assessing urine concentration is an important component of CKD diagnosis. Cats experiencing kidney failure can’t concentrate their urine, so abnormal blood work paired with diluted urine often means a cat has CKD.
• Imaging. X-rays or an abdominal ultrasound may be needed to see if your cat has a tumor, bladder or kidney stones, or a related issue that’s interfering with their kidney function.

👉 Annual blood and urine testing on cats older than 7 or 8 should also be considered to catch kidney disease in its earliest stage.

Chronic kidney disease is irreversible and progressive, so treatment focuses on keeping your cat comfortable. Management of kidney failure revolves around feeding your feline a high-quality diet, Trusted Source NC State Veterinary Medicine Veterinary school. Go to source encouraging them to drink water, and managing symptoms like nausea. Your vet may also prescribe a phosphate binder for your cat. Oral phosphate binders such as aluminum hydroxide help to lower the amount of phosphorus absorbed through the gut wall, making your cat feel better.

If your cat has been diagnosed with CKD, they may also be eligible for a clinical trial, such as those offered by The Ohio State University.

Although you can’t cure your cat’s CKD, you can provide a good quality of life for your feline friend. Ensuring your cat eats, drinks, and can hold food and water down is critical for their health, so follow these tips to successfully manage your kitty’s CKD:

Take your cat for regular checkups — Although you may not think your cat needs regular checkups after their initial CKD diagnosis, ongoing vet care is important, especially if you’re managing another disease, too. Your vet will evaluate your cat’s kidney function and overall health, and treat complications like anemia and hypertension if they arise.

Switch to wet food — Cats with CKD are often dehydrated, so switching to a wet food is recommended to ensure they get the water they need.

Try a kidney-friendly diet — A special prescription food formulated for cats with kidney disease, like this one from Hill’s, can help manage your cat’s symptoms. Prescription kidney diets are low in protein and phosphorus and often contain fish oil and antioxidants.

👉 Change your cat’s diet slowly. Mix 25% more new food into their old food every few days for a gradual change. 

Stimulate their appetite — Many pet owners say one of the most difficult parts of caring for a cat with kidney disease is their lack of appetite. A prescription medication like mirtazapine or capromorelin may pique your kitty’s interest and encourage them to eat.

Give your cat a nausea-reducing treat — Minimize the phosphorus in your cat’s diet by giving them a special treat. Egg whites, tuna, and chicken are good options.

Encourage your cat to drink — Adding a tiny bit of low-sodium chicken broth to your cat’s water is a great way to boost their water intake. Placing water fountains around your home for easy access to fresh water can also help.

Supplement essential nutrients — Cats in kidney failure tend to lose too much potassium in their urine, which can lead to muscle weakness, stiffness, and a dull or patchy coat. In addition, water-soluble vitamins, like B and C, are lost in diluted urine, so affected cats need daily supplementation. A powder or gel supplement like Renal K+ may be a good option for your cat, but check with your vet first to see what they recommend.