I took Daisy, our 15-year-old cat, to the vet to have her long sharp front claws trimmed. She had taken to jumping up on the bed every morning, expressing her desire for food and attention by scratching my forearms hard enough to make them bleed. The vet recommended a geriatric health screen. Daisy was kept in the clinic all day for blood and urine tests, and the results showed that her renal function was somewhat impaired. I agreed to another blood test to assess the extent of the problem.

Renal (kidney) failure is very common in older cats. The many possible causes include urinary infections and ingestion of poisons. In many cases no specific cause can be found, though I wonder if processed food is implicated, for example cats fed on dry biscuits may get too much salt and not enough water. Our own cats certainly love dry biscuits, but I have always limited their intake, and fed a mixed diet with moist canned food and fresh meat, poultry or fish. The symptoms of renal failure can include increased thirst, increased urine volume, loss of appetite and weight, vomiting, diarrhoea, and general weakness. It is sometimes associated with other conditions such as anaemia, hypertension and hyperthyroidism.

Although diet is an important aspect of management, according to my reading there is some controversy around this. The standard prescription foods are low in protein, but some experts recommend feeding plenty of protein from fresh high-grade animal sources. Medication may delay progression of the condition. Adequate fluid intake is important, and severe acute cases may need parenteral fluids. Some specialised centres even offer renal dialysis and kidney transplantation.

Daisy’s second blood test showed that her renal function was “borderline”. She appears very well and has none of the symptoms listed above. After a long discussion with the vet we agreed not to initiate drug treatment or a special diet at this time.

I was about to leave the clinic when I checked on her claws and found that they had forgotten to trim them, so she was taken back to have that done. It had turned out a very expensive manicure; I could have tried to do it myself at home, though I am sure she would have scratched me.

Whether investigation of Daisy’s renal function has been worthwhile, only time will tell. Both in veterinary and in human medicine, screening for disease has pros and cons. Sometimes it does pick up a serious condition for which early treatment is desirable and even life saving. But modern tests are so sensitive that they often detect very minor abnormalities, prompting further investigations which can involve a great deal of discomfort, anxiety and expense and usually prove to have been unnecessary. On several occasions I myself have had blood results, X-Rays or biopsies reported as “borderline” or “suspicious” that eventually turned out to have been false alarms.