I get this question from lots of readers whose cats have the altogether-too-common kind of kidney failure older cats tend to get. It's called chronic renal failure, and everyone wants to know whether they’re doing everything they can to help treat its symptoms.
Even if your cats have never suffered through renal failure, it’s worth thinking about. After all, if you’re lucky enough to be owned by enough cats, one is bound to live long enough to experience this disease. (Depressing thought, I know.)
1. Urination and drinking
This is often the first symptom owners of chronic renal disease cats notice: Large volumes of urine clotting the clumping kitty litter along with bowls of water downed in record time. Though it’s a sad sign of the negative change in kidney function, it’s also an important indicator of the kidneys’ continuing ability to function.
In the case of chronic renal failure, patients are simply trying to flush unwanted toxins out of the blood through heightened thirst and concomitant elimination. That’s why keeping tabs on continued high volumes when it comes to drinking and urination is recommended.
2. Nausea and vomiting
All those toxins the kidneys can no longer efficiently excrete lead to a major rise in some very nauseating chemicals in the blood. The brain responds by helping eliminate them via vomiting. Counterproductive though this may sometimes be (after all, everyone needs to take in nutrients to live), it’s a natural response. Plenty of drugs exist which may help limit the discomfort of nausea. Ask your vet for some recommendations.
The mainstay of most chronic renal failure patients’ care (especially in their advanced stages) is fluid therapy. Subcutaneous fluid administration is the most common route of fluid input in the long term, though intravenous fluid administration is typically preferred at the outset and may be necessary intermittently throughout the course of the disease.
Phosphorus is not your friend during kidney failure. Levels of phosphorus in the blood will rise as the kidneys’ ability to excrete it declines. Consequently, calcium levels rise to match the phosphorus load—and the calcium has to come from somewhere, right? The calcium-rich bones are subsequently leached of their stores, weakening them severely in some cases.
That’s why oral, phosphorus-binding drugs are needed to help rid the body of its excessive levels.
The kidneys make a hormone (erythropoietin) that triggers red blood cell production. This means that when the kidneys suffer, the blood suffers, too. Moreover, the excess of fluids these patients sometimes receive means their blood is always more dilute than it would otherwise be, effectively lowering the number of red blood cells making the rounds.
Anemia (low red blood cells in the circulation) is common to chronic renal failure cases and can be managed with nutritional supplementation of iron to a small degree and with synthetic or natural hormone supplementation (darbopoetin or erythropoitin, respectively) to a larger degree.
Secondary to anemia, malnutrition, nausea and/or weak bones comes an overall appearance of weakness. Muscle mass may diminish, leading to an inexorable downward spiral in activity and further weakness.
A subset of the nausea and vomiting issue, inappetance (often referred to clinically as anorexia, especially when the appetite level drops to nil) is often the most frustrating aspect of chronic renal failure in cats. These owners will do everything to bring back their kitty’s dinnertime exuberance. Drugs to stimulate appetite can be had. Some are actually moderately effective even when nausea-damping drugs have made no headway. Ask if your kitty’s a candidate.
8. Weight loss
Yeah, if you’d been on the verge of nausea for weeks, if not months, preceding your diagnosis without anyone noticing you’d probably manage to lose a significant percentage of your body mass, too. Keeping an eye on continued weight loss is important for most chronic renal disease patients.
9. Blood pressure
Sixty-one percent of cats with chronic renal disease have high blood pressure. But most cats never have this issue addressed (usually through drugs, like amlodipine). Truth be told, that’s because the other symptoms seem far more pressing, and because we’ve already taken steps to reduce blood pressure through the dietary changes we recommend (see below). Still, I’d consider blood pressure a minimally addressed consideration in kidney failure cats. For some, drugs can make a very real difference.
By far the most audibly controversial aspect of chronic renal disease therapy, nutritional treatment is nonetheless the most popular approach to mid- to long-term management of feline kidney patients. Low in sodium and protein, these diets are engineered to reduce blood pressure and limit the buildup of toxins produced by the breakdown of proteins, which must be cleared by the kidneys.
As mentioned previously, however, stimulating an inappetant, nauseated patient is complicated by these diets’ far cry from the naturally appetizing protein-rich fare cats are built to relish. In other words, these diets appeal only to the least nauseous and best eaters among felines. Sure, cats can be brought to an understanding of their necessity but doing so is often a challenge.
Cooking for chronic renal failure kitties is often a fruitful endeavor. Enlist a veterinary nutritionist for this. (More on this tomorrow.)
Finally, let me mention that all owners of chronic renal failure patients are welcome to request the advice of a board-certified internal medicine specialist during this process. Furthermore, owners who choose to consider dialysis (still available only in very limited geographic regions) and the possibility of a kidney transplant (available to limited numbers of renal failure cases) are urged to seek out advanced services as early after the diagnosis as possible.
Dr. Patty Khuly