The kidneys filter blood, selectively keeping in water and salt, and eliminating waste. Sure, some water loss is required to carry the waste out of your body in the form of urine, but for the most part, your water tries to stay inside you. We all lose water constantly through our pee, which (along with sweating, and panting if you’re a dog) is one of the reasons we have to take water in all the time.
As an extra bonus, the kidneys also produce molecules that stimulate red cell production and help regulate blood pressure. Who knew?
Renal Tubule Failure Leads to Kidney Disease in Cats
Like most filters, the kidney is made up of thousands of little components, called tubules. Each tubule filters a little bit of blood, keeps the good stuff inside, and spits out the bad stuff.
When a tubule stops working, good stuff (like water and salt) accidentally escapes through the broken down tubule, making a kidney failure cat’s pee more dilute.
The greater number of tubules that stop working, the more good stuff gets lost in the cat’s pee. The more water your cat loses through her pee, the more she has to drink to compensate for the loss.
Cats were not designed with good long-term kidney function in mind. As originally desert creatures, properly functioning cat kidneys can eliminate the body’s waste using only a VERY stingy amount of water – cat pee is usually very concentrated (as you may know if you’ve had to clean it up).
A trade-off for having highly efficient tubules is that they break down easily. As a massive simplification, most cat kidneys work AWESOME for about 10 years, then they start breaking down. Chronic kidney failure results.
Suddenly, the cat is peeing large amounts, all the time, because the kidneys are losing water faster than the poor cat can drink. Chronic dehydration results.
Chronic dehydration, salt loss and blood toxin buildup makes kitty nauseous and headachy, like a bad hangover that never goes away.
Salty fluids can be administered to the cat to compensate for the extreme loss of these fluids by the kidneys, and can help flush out the bad stuff in the blood. Cats have lots of loose skin, so it’s possible to give a cat a whole day’s water intake through a single under-the-skin administration of fluids at home.
What used to be an extra bonus function of the kidneys, stimulating red blood cell production and regulating blood pressure, starts to work against the cat. As red cell production drops, the cat develops anemia, which makes kitty weak and easy to fatigue.
Anemia from low red cell production is most often treated with B-vitamin supplementation, with or without iron. Weekly injections of B12 are the most common veterinary form of B-vitamin treatment, though oral liquid supplements are also available.
Low potassium or high phosphorus, if present, can also be treated with oral supplements.
Blood pressure also starts to climb, potentially leading to clots, blindness, or stroke. Blood pressure medicines like amlodipine or benazepril can be administered to help regulate blood pressure.
Cats in Kidney Failure Can Often Be Managed At Home
Essentially, treatment of cats with chronic renal failure can be broken down into:
1. Feeding a diet that produces as few toxic products inside the body as possible. The first therapeutic veterinary food, designed in 1948, was Hill’s Prescription Diet k/d, and now every veterinarian stocks prescription kidney food of various brands for cats.
2. Replacing lost fluids, often through every day or every other day subcutaneous fluid administration at home.
3. Boosting red cell production with B-vitamin supplements, if indicated.
4. Treating high blood pressure.
5. Treating electrolyte imbalances, especially potassium and phosphorus.
( Items 3-5 may require repeated visits to the veterinary office. )
If your cat has been diagnosed with chronic kidney failure and you’d like a one-on-one consult with Dr. Magnusson, please call our Indianapolis veterinary clinic at 317-721-7387.