How To Tell If My Pet Has Kidney Disease

By John Morgan | Dated November 9, 2015

Chronic kidney disease is one of the most common metabolic diseases in dogs and cats, being more common in our feline friends. Approximately 1.6% of cats and 0.9% of dogs are affected by kidney disease.  Before we look at  the disease process itself, it’s worth thinking about what the kidneys actually do.

What do kidneys do?

The kidneys play a vital role in conserving water in order to prevent dehydration, and in excreting waste products from the body. In fact, the kidneys link these two roles by aiming to excrete the toxic waste products in as small an amount of water as possible.  Additionally, they produce a hormone  that stimulates red blood cell production to help prevent anaemia. The kidneys also play a vital role in blood pressure maintenance and the balance of salts / electrolytes in the body.

What happens in kidney disease?

Kidney disease occurs most commonly in its chronic form, which is the result of gradual loss of kidney function over a long period of time.  In fact, we don’t usually see any outward signs of kidney disease until  approximately 2/3 of the kidney function is lost. At this stage, the kidneys are unable to concentrate urine, so when excreting the toxic waste products,  the kidneys also lose a large volume of water. Once approximately ¾ of a pet’s kidney function is lost, the toxin levels start to build up above acceptable levels, and they may develop abnormalities on blood tests.

How do I tell if my pet has kidney disease?

The early signs of chronic kidney disease can be very subtle, however the sooner the signs are detected, the sooner we can start treatment to help your pet.  Initially dogs and cats will start to drink more water than they used to, and you may notice that they need to  pass urine more frequently. So, if you find your pet has started to drink from your glass of water, or from the shower recess (or dare I say, toilet), or if you just seem to be refilling the water bowl more frequently than previously, then it’s time for a check up. If you are able to keep your pet from passing urine for a couple of hours before the check up, then there’s a good chance that the vet will be able to collect a urine sample to help asses their kidney function.

As kidney disease slowly progresses, pets will often feel less hungry and may not finish their meals and start to lose weight. Some may vomit due to nausea associated with the build up of toxins.  Cats will often lose interest in grooming, and you may notice that their coat doesn’t look as shiny and healthy as usual. Some owners comment that their pet just doesn’t seem their usual  spritely self!

These are all reasons for a kidney health check.

What tests will my vet do?

While being thirsty is a common sign of kidney disease, it also occurs commonly in a whole host of other illnesses.  In order to determine if your pet does indeed have kidney disease (or one of the other illnesses), once they have examined your pet thoroughly they will likely request a blood and  urine test, and possibly check your pet’s blood pressure.  These tests are routine, and remarkably pets rarely get worried at all about having a blood sample taken. Usually they are much more brave than their owners!

What do all those numbers mean?

The most important  results  in a blood test when we are testing for kidney disease are the urea and creatinine levels.

Urea is a waste product of the digestion of protein in your pet’s diet, and it is excreted by the kidneys. If the kidneys are not  working properly, and are unable to excrete the urea then it builds up in the blood.  The urea level can be influenced by other factors, in particular dehydration, so it’s always helpful to have a urine sample to test as well,  to clarify the result.

Creatinine is  a very useful indicator of kidney function, and like the urea level, when the kidneys are no longer excreting it effectively, the creatinine level in the blood rises. We tend to find creatinine a more reliable indicator of kidney function.

Urine tests are also invaluable when we are investigating kidney disease. Now don’t stress about this one. We don’t expect you to be able to collect a urine sample form your pet at home!  What we are most interested in, is ruling out any kidney infection or crystals, checking how concentrated your pet’s urine is (urine specific gravity),  and checking if they are losing protein in their urine.  These tests can be done in a flash, and provide invaluable information.

When we have a pet with kidney disease, it is also ideal to check them for anaemia, check their phosphorus level, and monitor their blood pressure and urine results so that we can adjust their treatment appropriately.

Where to from here?

If your pet has been diagnosed with kidney disease,

Equally important is their nutrition. There are several  diets that are designed particularly for patients with kidney disease, having  high quality protein at a reduced level compared to regular diets.

Keep in touch with your vet. Regular blood and urine tests are vital to monitor for changes so that appropriate medication can be given.  Together we can ensure that your cat or dog with kidney disease has the best of care.