Chronic Kidney Disease in Cats

Chronic Kidney Disease

The kidneys are vital organs in the body that play a key role in filtering blood, removing waste products, and maintaining a balance of electrolytes and fluids. We can see two types of kidney disease: acute (a sudden injury to the kidneys) and chronic (a gradual loss of function). 

Chronic Kidney Disease (CKD) is a common condition in older cats where the kidneys gradually lose their ability to function properly. This can lead to a buildup of toxins in the blood and can affect your cat's overall health.

Causes

CKD can result from various factors, including:

• Age (80% of geriatric cats will develop CKD)
• Genetic predisposition (Certain breeds, like Persians, are prone to disorders like Polycystic Kidney Disease)
• High blood pressure
• Infections
• Kidney stones, kidney mineralization, or other obstructions
• Toxins or certain medications
• Concurrent illness (such as diabetes)
• Rarely, kidney cancers
  

Signs and Symptoms

Signs of decreasing kidney function can be subtle, and cats can go a long time without feeling any effects. As it advances, we will see more serious signs.

• Increased thirst and urination
• Decreased appetite
• Weight loss
• Vomiting or nausea
• Lethargy or decreased activity
• Poor coat condition
• Bad breath (uremic breath)
• Mouth ulcers
  

Important Diagnostics for Cats with Kidney Disease

• Physical examination to trend weight loss, check for signs of dehydration, and other findings.
• Senior Bloodwork Blood
  • Urea, creatinine and SDMA to measure kidney function
  • Red blood cells will screen for anemia
  • Electrolytes such as phosphorous and potassium
• Urinalysis
  • Urine can be used to assess the kidney’s ability to concentrate urine, measure urine protein loss and screen for complicating factors such as infection. 
    • Urine Protein:Creatinine Ratio can be added to accurately assess or trend urine protein.
    • Urine Culture can be performed to fully rule out infection.
• Imaging
  • Ultrasound or X-rays if necessary to screen for kidney stones, misshapen kidneys, or other kidney abnormalities.
    

Management and Treatment

Chronic kidney disease is progressive and kidney function cannot be returned once lost. However, there are a lot of options to try to slow down progression and maintain good quality of life for our cats.

1. Kidney Diets: Special diets low in protein, phosphorus, and sodium can help reduce the workload on the kidneys and decrease the build-up of toxins.
2. Hydration: Since the kidneys are usually responsible for saving fluid, we have to take extra care to ensure cats are consuming enough fluid to stay hydrated. Ensure there is always access to fresh water. Mix warm water to canned food for extra water.
   • If cats are unable to consume enough fluid to maintain their hydration, we can add regular subcutaneous fluids (fluids under the skin).
     
     
3. Phosphorus binders: High phosphorous levels can be a consequence of kidney disease, and can contribute to symptoms. Phosphorous binders (usually powders) can be added to manage this, or added to other diets to make them more kidney friendly.
4. Potassium supplements: Healthy kidneys help keep potassium levels up. With kidney disease, the body can lose too much potassium, which can lead to weakness and lethargy. Supplementing extra potassium will help this.
5. Medications for high blood pressure: Since the kidneys play a major role in regulating blood pressure, we should monitor blood pressure and treat if it is consistently elevated. High blood pressure can lead to sudden blindness and stroke.
   
   
6. Medications for urine protein loss: We can add medications to prevent excessive protein loss in the urine.
   
   
7. Anti-nauseants: Nausea and vomiting can be a result of CKD. We can add regular anti-nauseant medications to help this.
   
   
8. Appetite stimulants: It is common for cats with kidney disease to eat less and lose weight. We can add appetite stimulants to improve this.

What to watch for in a cat with chronic kidney disease:

1. Pay attention to hydration: Because the kidneys have lost function, they have decreased ability to “save” water in the body, which makes our CKD cats more prone to dehydration. Unfortunately, symptoms of dehydration can be very vague. Mild dehydration may just look like hard stools or higher risk of constipation. As it progresses, we can see lethargy and decreased appetite. A quick assessment is to gently lift up and pinch the skin – if the skin holds the “tent” shape, it is an indication of dehydration.
   • Always ensure access to fresh water. Some cats will drink more if there is running water (like a fountain… or a tap if they are spoiled!). 
   • It is best to feed canned food daily, with extra warm water added if they don’t mind.
   • Sometimes, we reach a point where cats are just unable to maintain their hydration by water they consume on their own. If this is the case, we can consider giving them regularly subcutaneous (under the skin) fluid treatments (either in clinic, or we can teach you how to do it at home).
2. Weakness and lethargy: There are a few reasons why a cat with decreased kidney function may be acting weaker. Exam and bloodwork can help tell us why.
   • Dehydration, as discussed above.
   • Anemia: The hormone that tells the bone marrow to make more red blood cells (called erythropoitien) is produced in the kidneys. Therefore, if the kidneys are not working 100%, we can see anemia (low red blood cells). In some cases, we will consider supplementing iron and/or medications that mimic erythropoietin.
   • Decreased potassium: Called hypokalemia, we can see decreased potassium secondary to kidney disease. This causes muscle weakness that is most obvious in the neck and hindlimbs. Supplementing potassium under direction of a veterinarian is an easy way to help this.
     
     
3. Changes to urination: It is normal for cats with chronic kidney disease to have larger or slightly more frequent urinations. However, CKD cats are also more at risk for urinary tract infections. Signs of a UTI can include smaller, more frequent urination, straining to urinate, urinating out of their box, bloody urine, and/or a foul smell to the urine. If you see any of this, it is a good idea to perform a urinalysis (+/- urine culture) to look for an infection.
   
   
4. Decreased appetite, pickiness with food, and vomiting: The build-up of metabolic waste products can make cats feel nauseous, which leads to low appetites, pickiness and increased vomiting/hairballs. Diets intended for kidney disease may help reduce this, as they are designed with a balance of protein/carbs/fats to minimize waste products. Many cats will benefit from rotating through different flavours of food to keep them interested. If appetite and vomiting is still a problem, we should consider adding an anti-nauseant medication (eg. Cerenia) to the care plan. If cats still are not eating well, we also try an appetite stimulant medication (eg. Mirtazapine) which gives them the munchies.