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Myth 3  :  Kidney failure – ACE inhibitors and urine tests.

Chronic kidney disease is very common in older cats. Diagnosis needs blood and urine tests. Blood tests measure urea, creatinine, and phosphate – all of which are eliminated effectively by healthy kidneys.

In a small percentage of cases, significant amounts of protein are also lost in the urine (proteinurea). Medication known as ‘ACE inhibitors’ are often used to treat proteinurea. The benefit of these drugs in treating protein loss is open to debate - one for another time! However, if there is no proteinurea, there is no justification for their use. ACE inhibitors include Fortekor and Semintra.

Proper diagnosis of kidney disease demands urine tests in addition to blood tests. Be wary of ‘slightly raised’ kidney figures – without careful interpretation and urine tests this is not evidence of kidney failure. Your vet should be able to give you an IRIS stage for your cat’s kidney disease.

Kidney diets are often ‘prescribed’, however they are not always appropriate. One effect of kidney disease is a reduced ability to retain water in the body – hence the dilute urine and copious widdling. Dry renal diets are therefore counter-intuitive, as we want to get as much water as possible into our kidney cats.

Renal diets usually have reduced protein levels. There is little proven benefit in reducing protein intake – indeed if your cat is losing weight, restricted-protein diets are contra-indicated. Moreover, for a cat that has poor appetite due to kidney failure, the last thing it needs is to be forced onto a new diet that it refuses to eat . More important is to keep the cat eating whatever it will eat in the first instance. The diet can be modified subsequently.

So, in summary,