I am including this information because so many people seem to blame themselves for their cat's illness, when in truth CKD is rarely avoidable - as the What Happens in CKD page mentions, around 10% of cats over the age of ten will develop CKD, with as many as 30% of cats over the age of 15 having the disease.
This page is divided into known causes of CKD and possible causes.
The possible causes section is just that at this point, possible causes. This section is not there to make you feel guilty about, say, your food choices. There is no hard evidence that any of these possibilities truly do cause CKD, although the anecdotal evidence is stronger for some than for others.
On the left is a list of this page's contents.
Many people who contact me want to know what has caused their cat's CKD because they are worried that they did something wrong, and want to ensure they do not do the same thing with their other cats.
CKD is not actually that simple. There are a multitude of possible causes, which I outline below, but in many cases you will never find out the most likely cause in your cat's case.
Try not to feel guilty because the cause is unlikely to be anything within your control. Most cats with CKD have changes in their kidneys known as chronic interstitial nephritis, and this is largely related to old age, affecting around 10% of cats over the age of ten, and as many as 30% of cats over the age of 15. So unless you have mastered the art of arresting aging in your cat (and if you have, please let me know immediately), the chances are it is just a combination of inflammatory processes, the passage of time, and bad luck. Renal fibrosis in feline chronic kidney disease: known mediators and mechanisms of injury (2015) Lawson J, Elliott J, Wheeler-Jones C, Syme H & Jepson R The Veterinary Journal 203(1) pp 18-26 says "It is thought that the intra-renal environment in CKD is significantly pro-fibrotic, leading to continued production of pro-inflammatory and pro-fibrotic cytokines and the perpetuation of the wound healing response rather than its resolution. The factors with the most influence on maintaining this state and which have undergone the most investigation to date are believed to be proteinuria, chronic inflammation, hypoxia, ageing and hyperphosphataemia."
Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals (2014) Greene JP, Lefebvre SL, Wang M, Yang M, Lund EM & Polzin DJ Journal of the American Veterinary Medical Association 244 pp320–327 found that "Risk factors for CKD in cats included thin body condition, prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year, being a neutered male (vs spayed female), and living anywhere in the United States other than the northeast."
Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 concludes "Results of our study suggest there is no single risk factor, exposure, or predictor that can explain development of CKD in cats and therefore cumulative effects of multiple risk factors and interactive factors should be considered. Cumulative exposure to risk factors in certain possibly genetically predisposed cats may contribute to a decrease in renal function."
Management and treatment of chronic kidney disease in cats (2016) Caney S In Practice Oct 2016 pp10-13 states "CKD is the end result of a wide range of primary disorders that cause irreversible damage to nephrons, eventually leading to reduced glomerular filtration rate (GFR). In a minority of cases a specific underlying cause can be identified, for example, neoplasia, polycystic kidney disease, renal amyloidosis, hypercalcaemic nephropathy. However, in the majority of cases no primary cause can be identified; in these cases tubulointerstitial nephritis and fibrosis are the most common histological changes, likely to be the end result of a degenerative process initiated by factors including, but not limited to, repeated episodes of renal tissue hypoxia, exposure to toxins, glomerulonephritis, pyelonephritis and repeated transient ureteral obstruction due to ureterolithiasis." She also says "In the majority of elderly cats with CKD the primary cause of the problem cannot be identified. However, in selected cases further investigation may identify the underlying cause of CKD, which may be helpful to owners and in some cases may open avenues of treatment to address the primary problem. In general, seeking a primary cause is more likely to be rewarding in younger cats and in cats with enlargement of one or both kidneys."