A cat’s kidneys are impressive organs, capable of filtering blood and producing much more concentrated urine than that of humans. Despite this high functioning ability, elderly cats are at high risk for the development of “Chronic Renal Failure” or CRF. Kidney disease is present in a large number of older cats, with some studies suggesting up to 70% of elderly cats have some degree of insufficiency. Screening for kidney disease and its associated conditions is an important part of healthcare for your aging cat.
Types of Kidney Disease
Kidney disease may present as acute (sudden onset) or chronic (long term) renal failure. Acute kidney failure is often due to cats eating poisons such as lilies or antifreeze; but can also be due to infection. Chronic kidney disease is more common, and is often of the form referred to as “interstitial nephritis”. This is a non-infectious cause of kidney failure the results in small, non-functional kidneys over a prolonged time period.
The early signs of CRF in cats include increases in drinking and urination. Despite increased water intake, cats with CRF are chronically dehydrated. Urinary tract infections and constipation may also occur as related issues. As kidney disease progresses, cats will experience muscle wasting, feelings of nausea, elevated blood pressure and urinary protein loss.
Other kidney diseases in cats include pyelonephritis (infection of the kidney), cancers of the kidney (most often “renal lymphoma”), or less commonly diseases like FIP or amyloidosis. Cats may also have congenital kidney issues such as polycystic kidney disease, which is most common in the Persian breed.
Clinical signs of kidney disease include increased drinking and urination, high blood pressure, and muscle wasting. These are not specific to kidney disease however, and so full diagnosis and staging requires a combination of bloodwork (specifically the chemicals “urea” and “creatinine”), urine analysis (including specific gravity and the presence of protein), and blood pressure measurement.
X-rays and ultrasound may also be indicated for some cats in order to rule out less common issues and determine which kidney is more severely affected.
Kidney disease in cats is divided into 4 stages and several sub stages by IRIS, the “International Renal Interest Society”. This staging scheme allows the development of specific treatment plans and creation of an accurate prognosis.
Management and Prognosis
Management of kidney disease is focused on reduction of clinical signs and preservation of quality of life. There is no cure for Chronic Renal Failure in cats; as kidney transplants are not widely available and have a poor success rate.
Management of early kidney disease is focused on maintaining good hydration levels and treating secondary issues. As disease progresses medications may be needed to reduce blood pressure, prevent the loss of protein in the urine, and manage nausea and appetite loss. Dietary supplements may be needed to reduce phosphate levels and increase potassium.
Written by Dr.Matthew Kornya