By Dr. Donald Consla, Lead Wellness Veterinarian
As cats age, there are several diseases that are more commonly seen in this species like hyperthyroidism, diabetes mellitus and alimentary lymphoma, just to name a few. One condition that many are familiar with, unfortunately, is chronic kidney disease.
Chronic kidney disease is a form of kidney failure that takes place over an extended period. Over time, the functional kidney mass is replaced with scar tissue and the kidneys shrink. They are unable to do their job which includes water conservation, electrolyte balance, filtering out toxins and initiating red blood cell synthesis.
Knowing these normal functions helps us determine the clinical signs of chronic kidney disease. Affected cats tend to urinate large volumes because their kidneys are not conserving water. Subsequently, they drink more to try to stay hydrated. Various electrolytes may increase or decrease, and they may become anemic due to a decrease in red blood cell production. These patients will also have clinical signs secondary to the kidneys not excreting toxins in the urine such as vomiting, poor appetite, diarrhea, bad breath and neurologic signs. One thing to remember is that this disease is slowly progressive, and it can take years to go from the cat drinking and urinating more to losing weight and having GI upset.
Diagnostics can take a long time to change as well. Urinalysis, bloodwork, blood pressure measurement and ultrasound are the most helpful diagnostics to detect this condition. The kidney values on bloodwork can increase for other reasons than just kidney trouble so we always need to pair bloodwork with a urinalysis.
Typically, we will start to see dilution of the urine when 66% of the kidneys are no longer working. Traditional bloodwork changes like an increase in blood urea nitrogen (BUN) and creatinine will occur when 75% of the kidneys are no longer working. Finally, our feline patients tend to get very sick with lethargy, vomiting, diarrhea and dehydration when 90% of the kidneys are no longer working. Throughout this process, these patients can develop high blood pressure and lose protein in their urine. There is a new blood biomarker (SDMA) that has the potential to detect poorly functioning kidneys sooner than traditional bloodwork.
Treatment is a multi-faceted approach. These cats are put on a prescription kidney diet with lower protein levels which directly helps to reduce some of the toxins that can make the cat feel unwell. We may recommend fluid therapy depending on how sick the patient is, with an IV or fluids under the skin, or some owners may opt to do the latter at home. We can manage appetite, vomiting, blood pressure and protein loss in the urine with various medications.
It is important to have your cat’s blood and urine tested once a year because kidney disease can be caught early and treated long before your cat starts to feel sick. A chronic kidney disease diagnosis can feel overwhelming, but many of these patients do quite well and live long, happy lives.