Your pet’s kidneys are very, very busy. The kidney is famous for producing urine, but it has so many other important jobs. And when there is trouble with the kidneys, it affects a lot of other body systems, too.
Normally, your pet starts off with two kidneys. Very occasionally, pets are born with only one functioning kidney, but for the most part, it’s safe to assume that your pet has two kidneys. Each of those kidneys is made up of thousands of tiny filtration units, which are called nephrons. When a nephron is damaged or destroyed by disease, it is lost forever. Nephrons cannot regenerate.
Luckily, your pet is born with a lot more nephrons than he actually needs. In fact, he can lose up about 75% of his nephrons before he will show signs of kidney disease. While this seems like a good thing, it also means that by the time your pet shows signs of disease, it’s usually pretty advanced.
Kidney disease in pets can be acute (meaning its onset is very fast), or it can be chronic (meaning it has been going on for an extended period of time). Either way, the function of the kidney is decreased, and that means that all the jobs it does are also compromised.
The kidneys are responsible for conserving water in your pet’s body, but pets with kidney disease will urinate excessively. When the toxins that are normally produced every day in the body circulate to the kidneys, they are filtered out by the kidneys into urine. Kidneys that are functioning properly will be able to excrete toxins into a very small amount of urine, thus conserving water for the body’s use. When there is a loss of nephrons, such as in chronic kidney disease, the ability of the kidney to concentrate urine is lost and more water will be needed to excrete the same amount of toxin.
Your pet will drink more water to try to keep up with the loss, but eventually he will fail simply because he cannot drink enough water. At this point, toxins will build up and you will start to see additional signs of kidney disease. Nausea, vomiting, lethargy, decreased appetite and weight loss are sure to follow after the initial signs of drinking more water and an increase in urination.
Every job that the kidney does can be compromised, so other problems that may follow include:
- Anemia: The kidney produces the hormone erythropoietin, which stimulates the production of red blood cells. Without it, our pet’s red blood cell levels drop.
- Electrolyte imbalance: Calcium and phosphorus are in delicate balance in our pet’s bodies, and the kidneys play a large role here. Potassium levels may become too low as excess potassium is lost through the urine.
- Low protein levels: Kidneys can lose the ability to filter out protein, and it may be lost in the urine, leading to low blood protein levels.
- High blood pressure: Because the kidneys regulate blood pressure, their failure will lead to increases that need to be managed medically.
Kidney disease can happen for any number of reasons, whether it be infectious (such is the case in Leptospirosis, which we’ll cover in a blog later this month) or just due to old age. Each case will be managed differently, depending on how severe the disease is and which clinical signs your pet displays. While acute kidney disease can sometimes be treated with no long term effects, chronic kidney disease is on-going through the life of the pet. Talk to your vet about which medical therapies are available for your pet.