Chronic kidney disease in cats (CKD)

Chronic kidney disease in cats (CKD) is a progressive, incurable disease of predominantly older cats. Over the course of the disease, the kidneys lose their ability to excrete toxins (including “uraemic toxins”) and to perform their various functions, such as balancing body water, salts and acids and producing hormonal substances involved in blood formation, bone metabolism and blood pressure regulation. This gives rise to a great number of complications and related clinical symptoms, mostly in the late stages of the disease. That’s also why owners usually only notice the disease a long time after its inception.

CKD in cats was formerly known as chronic renal failure (CRF). The incidence of CKD increases from the age of 5 to 6 years. One in three cats over the age of ten is affected by CKD.

The disease is one of the most common, and thus most important, causes of death in cats.

It develops gradually over months and years. There is no cure for CKD in cats. Treatment, therefore, focuses on slowing down damage to the kidneys and alleviating clinical symptoms.

Nephrons are replaced by scar tissue

CKD in cats can develop for a variety of reasons. Inflammation (in the kidneys and other organs, but also dental abnormalities such as FORL), tumours, and also kidney cysts, poisoning, kidney stones, acute kidney damage and, rarely, birth defects can lead to CKD.

The shared feature is that at some point the nephrons (the filtration units of the kidneys, also known as “functional units”) degenerate, usually due to inflammatory changes, and are replaced by scar tissue. This scar tissue cannot perform the tasks of healthy nephrons (filtration units), however, and the kidneys are therefore no longer able to completely fulfil their various tasks. The resulting decrease in renal function is referred to as renal insufficiency. As the degenerating nephrons are replaced by scar tissue, the amount of scar tissue is directly related to loss of renal function. A large amount of scar tissue is, therefore, associated with a poor prognosis. As it progresses, the disease is characterised by further destruction of nephrons and increasing scar tissue. The scar tissue leads to a hardening of the kidneys. The kidneys, therefore, undergo massive changes in CKD. Depending on the cause, they can become either smaller or larger.