How many cats will have kidney disease during their lifetimes?
The answer is 1 in 3, and cats age 15 or older have a 1 in 2 chance of suffering from kidney disease.
It’s easy to get depressed about your cat succumbing to kidney problems, but this shouldn’t be the case. In fact, when kidney disease is detected early, there’s every chance that appropriate management will help your cat live for many more years.
The trick is to find out early if there’s a problem and then take control.
Think of this like the doctor monitoring your blood cholesterol levels. If he spots a rise, you can change your diet or start statins and drastically reduce the risk of complications.
The problem with kidney disease in cats and other animals is that the existing tests (including blood creatinine) aren’t particularly sensitive. Indeed, you may be shocked to learn that blood creatinine levels leave the normal range only once a cat has lost 75% of his kidney function.
In other words, your cat is functioning on just half a kidney before we know anything about it. If you’re a half-full person, it’s wonderful how efficient our organs are, but if you’re a half-empty person, this is alarming news.
However, a new blood test picks up kidney disease far sooner. This is fur-bulous news because, just like with our own blood cholesterol, if we pick up the signs early, we can change the cat’s diet, protect the kidneys and delay deterioration.
The New Test
The new test is called symmetric dimethylarginine (SDMA). It works by measuring proteins released from damaged tissues. These proteins are filtered and discarded by the kidney, and with healthy kidneys the levels are low. But when 40% of kidney function has gone, the blood levels rise.
Now, if you’re thinking that 40% damage still seems high, think what happens when people become a living organ donor. These people donate 1 of their 2 kidneys, instantly reducing kidney function by 50%, and yet they remain fit and well. In other words — we carry a spare, so a 40% reduction is no big deal.
However, what SMDA flags is an early warning that allows us to protect those precious kidneys. By adjusting the diet so the kidneys have less work to do, they are significantly protected. This means, in most cases, you can stall or drastically delay further deterioration.
Get Your Cat Tested
Ask your veterinarian. It’s just a simple blood draw, much like any other blood test. It’s a great idea to test any cat age 8 or over, because this is the age at which problems start to set in. Until now, vets have reached a diagnosis based on late-stage tests such as:
- Blood creatinine: Above normal once 75% function is lost.
- Urine concentration: Urine becomes weaker once 60% function is lost.
You need to be alert for signs of kidney disease, including:
- Increased thirst
- Weight loss
- Bad breath
- Poor coat condition
- Mouth ulcers
These can be vague, and other conditions can cause similar symptoms, but they should indicate that a vet check is necessary.
Treating Kidney Disease
The kidney is a filter — it gets rid of naturally occurring toxins that are the waste products of digestion. However, diseased kidneys can struggle to cope, and then the level of toxins build up in the bloodstream (this is what the blood creatinine test measures).
These toxins make the cat thirsty and feel unwell. Also, a downward spiral begins where the kidney sustains further damage as it struggles with an increased workload.
Key to protecting the kidneys is giving them less work to do, hence the importance of prescription renal diets:
- Examples include Hills K/D, Purina’s NF and Royal Canin’s Renal Support foods.
- They are low in minerals that cause scar tissue to develop and contain high-quality protein in reduced quantities.
- The proteins are “purer,” and once digested, they are lower in waste products, which puts less strain on the kidney.
In the early stages of kidney disease in cats (detectable by SDMA), a simple diet change may be all that’s required to stall deterioration for quite some time. In later stages, medications may be added that assist kidney function as well as food additives that further reduce phosphate levels absorbed from the gut.
Know that early detection of kidney problems puts you in control, and you do not have to fear the diagnosis.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 13, 2018.