Vancouver Feline Hospital - Cat Veterinary Clinic

4. Conserving potassium
Potassium is an electrolyte which must be delicately balanced within the body's cells for muscle function. The heart is a muscle and is affected by potassium levels. Potassium is eaten - that is, your cat gets it from the food. The kidneys have to prevent potassium from being excreted in the urine. So in a cat that isn't eating enough, potassium loss can be critical. In CRI, the kidneys are not able to conserve the potassium as efficiently, and because of renal gastritis, the cat doesn't want to eat, or is vomiting. Low potassium levels are noticeable by weakness, walking with dropped hocks, head hung low, lethargy.

Serum (blood) potassium levels can give an indication of lack of total body potassium levels. Normal blood levels may mask a lack of potassium in the cells, which is the critical parameter, but we have no way of measuring that yet. The veterinarian may suggest supplementing dietary potassium even with normal blood values, based on clinical signs.

Potassium gluconate can be added to your cats food. Some cats will refuse food with anything added, in which case you may have to give a syrup or tablet daily. It is possible but not desirable to add potassium to the SQ fluids, because this will change the solution and cause it to sting. It is also easy to overdose potassium (fatal) if giving it SQ but impossible to overdose if giving it by mouth.

5. Blood pressure control
The kidneys are very important in controlling blood pressure. Hypertension (high blood pressure) is unrelated to the degree of azotaemia (BUN and CREATININE levels) and may not occur in every cat with CRI. Cats don't complain, so this is a problem that is chronic but presents acutely - your cat may have had high blood pressure for months or years, but the first time you may find out about it is when your cat has a stroke or goes suddenly blind. Treatment of hypertension often results in a happier cat. It seems they do feel groggy, headaching and grouchy with high blood pressure. The side-effects of acute bleeding caused by the hypertension (stroke damage, blindness from retinal detachment, functional tissue loss in the kidneys, heart muscle, adrenal glands and so on) cannot be cured, but we try to prevent further damage.
Blood pressure should be checked every visit, using a Doppler paediatric system. The "white coat effect" (rise in blood pressure due to stress caused by the visit to the vet) is taken into account.

Full retinal (eye) exams using an opthalmoscope and dilating the pupils may show changes to the retinal blood vessels and small pinpoint bleeding zones in the retina typical of hypertension.
Always treat hypertension. A small tablet once or twice daily (amlodipine is our drug of choice).

6. Calcium balance
Yet another metabolic role of the kidneys. The kidneys remove phosphorous from the body and are involved in vitamin D activation. Calcium homeostasis (balance) involves a whole body choreography of vitamin D, calcium and phosphorous. When calcium and phosphorous levels build up, the bones become like rubber and the excess minerals deposit in soft tissues, causing inflammation and pain.
Blood phosphorous and calcium levels are included in the blood tests.
Diets low in phosphorous are usually recommended - for humans. These are low protein diets (high levels of phosphorous in meat) and as already mentioned, that doesn't work for our little carnivores. We can add phosphate binders to the food (if the cat eats it) - amphogel, sulcrate work well, but long term high doses can have undesirable side effects. Some cats benefit from calcitriol treatment. Do not self treat your cat with over the counter vitamin supplements - these can be very harmful!

7. Maintaining electrolyte and acid-base balance
These go awry with failing kidneys and the effects can be subtle (just not feeling right) to severe (respiratory distress and heart failure).
Sodium, chloride, potassium, and some acid-base measurements are included in the blood tests.
Maintaining hydration by increasing water intake and SQ fluids manage this very well.

8. Urine protein loss
This happens whenever the cat has inflammation in the kidneys or elsewhere in the body (most common cause is periodontal/dental infection).
Urine protein loss has some prognostic value - if the urinalysis does not show proteinuria then that is good news!

Microalbinuria is a very sensitive early indicator of urine protein loss, and can be our earliest indicator of renal disease, showing positive before the blood tests.

An ACE-inhibitor (traditionally a heart medication - but it works on the whole kidney-heart-blood pressure control system) benazepril (Fortekor) has been shown to improve survival time in cases with proteinuria. This drug is licensed in the UK for chronic renal kitties. If microalbinuria or proteinuria was noted, we suggest benazepril treatment.

Well, that is scary! So what really happens?

We manage cats with CRI by following the core concepts of feline medicine - Fluids, Food, Quality of Life. Not every cat needs every single treatment listed above, and certainly not every cat goes through each complication. Most cats live many years with stable CRI when the only change has been lifestyle - providing more water and feeding canned food. When they need it, we add SQ fluids into the regime - as often as they need it, which varies cat to cat. We recommend more frequent check-ups - every three months. These check ups MUST include a complete physical exam, weight check, retinal exam, blood pressure check. Stable cats (ie no weight loss or other signs of illness) can have blood and urine tests done annually.

If your cat is stable CRI and then you notice a problem - get a full check up done immediately. Because the urine is so dilute, CRI cats are more prone to kidney and bladder infections. They can develop the other problems of age such as hyperthyroidism, so don't assume that peeky behaviour is just due to kidneys! Most concurrent problems can be treated successfully.

When the time comes to be adding all those other medications, you and your veterinarian need to chat about quality of life - what it means to you and your cat. Each cat owner is different in what they can do, so whether you want a renal transplant for your failing kitty, or medication is definitely not an option, you need to communicate this all to your veterinarian so that the two of you can work together to the benefit of your cat.