All About Kidneys

By Heather Duncan, D.V.M.

Today we’re going to talk about kidneys and their role in dogs and cats’ health. So what do the kidneys do? Well, you know most of us think they help make urine and you’d be right. However, they do a lot of other functions as well. There are many things that we don’t even think about that makes the kidneys so important to our pets daily health.

First, they conserve water. Not only do they help by pulling in the water and making sure your body stays hydrated, such as times of dehydration but if you drink too much water they help get rid of it. So it’s super important in keeping that water balance and that’s probably the reason why everybody knows that’s what they do because it is one of the most important things that the kidneys do.

Second, they help remove toxins. They get rid of biological waste or metabolic waste that our body is producing on a daily basis. Some of the ways which you may hear when your doctor or your nurse is going over blood work are things like (BUN) which stands for Blood Urea Nitrogen or Creatinine. A BUN test is done to see how well your kidneys are working. Both of these are by-products and metabolic processes and when they build up in the bloodstream they actually can make you very sick. It’s called Azotemia.

Other things the kidneys do are calcium and phosphorus balance. It helps to get rid of phosphorus in your system. If one or the other is lacking or too much it can actually lead to a lot of problems, including crystal deposition in muscles and in the bone. It can even make your bones rubbery. So super important aspects of kidney balance there. Another thing that the kidneys do is sodium potassium balance. It helps control these electrolytes and keep in mind that if the kidneys lose their ability to help conserve potassium and potassium levels begin to drop then you start to feel really weak and really tired and it can actually lead to some heart problems as well.

Did you know your kidneys were super important with blood pressure regulation? Kidneys actually have sensors in them that help regulate the blood pressure in the whole body. It is one of the organs that does that and so when these are damaged it can actually lead to hypertension or high blood pressure and that can lead to more damage of the kidneys.

Protein conservation is another big one. Your body uses a lot of proteins and they’re constantly circulating in the bloodstream and if your kidneys lose the ability to work properly then your body can not conserve proteins.

Kidneys are incredibly important for red blood cell production. Your red blood cells in your body are constantly being produced and they’re constantly being lost. So we have multiple factors and multiple processes in our body that help to regenerate these red blood cells and one is the kidneys. The kidneys produce a hormone called erythropoietin and if you lose enough of these nephrons or functional units of the kidneys they can’t produce this hormone and then you stop producing red blood cells. So that leads to some serious problems especially in dogs and cats because we don’t have a great substitute for this hormone to supplement them. We can use the human form but it doesn’t always lead to good results so sometimes in severe kidney failure cases the only treatment option we have is a blood transfusion.

Finally, kidneys are super important for pH balance. Metabolic processes within your body function at a very narrow pH range and if that is thrown off by any means then you’ve got some problems. So the kidneys help manage that.

So why am I even talking about this? Well it’s because kidney disease is a very common finding in our pet population. It is one of the most common things I see. When we’re doing annual blood work we want to catch it as early as possible. If not then we’re not going to see the changes until the pet is starting to show clinical signs. So what are the clinical signs? Well you got to look at what the kidneys do. So the first thing that you typically will see is increased thirst and increased urination. It’s because the kidneys are not conserving the water the way they would typically. Then you might see things like they’re not eating very well, maybe they’re vomiting, maybe they’re losing weight, maybe they are lethargic or acting drunk in severe cases. All of those are signs of kidney disease. Hopefully if we catch it early enough we will not see as many clinical signs for a long time

So what causes kidney disease? There can be multiple factors. One that we see is just aging changes. Geriatric changes to the kidneys as nephrons start to just die off due to normal wear and tear. Other problems can be caused by bacterial infections or the fancy word for that is pyelonephritis. We also have things like cancers and congenital defects where you’re born with abnormal kidneys. Toxin exposure can be another reason. Some toxins might be medications like ibuprofen, different toxins that are in your garage such as antifreeze and even plants in your house.

So what do we do about it and how do we cure it? Well, the unfortunate truth is that there is no cure in most cases for kidney disease. If we can catch things like infection, toxins or in some cases cancer early enough we can provide treatment options. Changes due to aging and congenital defects are a little bit more difficult. There are kidney transplants that are available. They are typically done through academic institutions such as vet schools and can be very costly. There are very narrow parameters that qualify a patient to get a kidney transplant and guess what, you leave with two pets because you typically have to adopt the donor animal. So realistically that’s not an option for many people.

So what we do is manage it. It’s a disease that we managed and we do that by addressing the different things that the kidneys do. So first we control water consumption. We want to make sure that we always have fresh water. Sometimes that includes getting a water fountain. Cats especially love that movement from the water fountain and so they drink more. We generally will switch their diet. There are many prescription kidney diets on the market and they hit some of the aspects of kidney function just in a diet change. Diet changes can help potassium regulation, phosphorus regulation, protein management and if we switch to a canned food it also helps with water consumption and dehydration issues. Speaking of dehydration, if we can’t manage that and control it with diet and water intake alone, then we’re going to teach you how to do fluid underneath the skin at home and it is surprisingly easy. So don’t be worried about that and it is something that we can teach most people. Kidney disease also leads to hypertension and blood pressure issues. So that’s something we’re going to want to check regularly so that we can catch it early and treat it earlier. We want to make sure that they feel good and sometimes that involves adding in an antacid to help reduce vomiting and encourage them to eat. Sometimes we have to add an appetite stimulant if they’re not eating well enough

The big takeaway with this is, our pets are born with two kidneys and millions of nephrons and as our pets live their lives, these nephrons are either going to die off due to disease or simply because of wear-and-tear and normal aging changes. When they are down to less than a third of their kidneys functioning nephrons, then we’re going to start seeing changes in their blood work and that’s why we really recommend annual blood work. It’s to catch problems as soon as we can and start some early changes to help your pet live longer and healthier lives. If you have any further questions please feel free to give us a call at (843) 236-6080.