Chronic renal insufficiency - Diet, Water, Supplements
I recommend that ALL cats, regardless of gender or age, be fed canned cat food. In the case of "kidney cats" specifically, canned food provides necessary water and prevents the cyclical dehydration that occurs when cats eat dry food.
Imagine, if you will, what happens when a cat eats a meal of dry food. The cat needs to produce a lot of saliva in order to be able to swallow the food it's dry! When the slightly moistened food arrives in the stomach it needs even more fluid added to make it semi-liquid so that is can pass from the stomach (large diameter) to the small intestine (small-diameter). This additional fluid is drawn first from the stomach itself, and then from the bloodstream. When the fluid in the bloodstream is depleted the sensors in the cat's body recognize dehydration, which triggers thirst and the cat goes and has a big drink.
So what's the problem? The cat has a drink of water and all should be well, right? Not exactly. The problem is that during the period when the cat is relatively dehydrated the blood is thicker than normal, and blood flow to the kidneys becomes sluggish. This results in further microscopic damage to the kidneys, making the kidney disease worse. And this can happen many times throughout the day as the cat eats several meals.
Also, sick cats often fail to drink enough in the first place, never mind drinking enough to make up for losses through the kidneys. These transient periods of mild dehydration sometimes are not corrected by drinking, and the cat remains in a chronically dehydrated state.
Feeding canned food helps to avoid the yo-yo effect of dehydration after eating, because large amounts of fluid are not required in order to digest it. It's already pretty wet!
One of the "derangements" we see with renal disease is an imbalance in the calcium and phosphorus levels. There are a few reasons for this, but the physiology is less important than the result. A lot of renal insufficiency cats have high phosphorus levels in the blood. We need to decrease the phosphorus levels in the body, as this can lead to all kinds of problems of its own.
One way to limit the amount of phosphorus is to feed a low-phosphorus food. Most of the prescription diets for kidney disease are restricted in protein and in phosphorus. However, it is not necessary to restrict protein in these cats, and sometimes protein restriction is actually contraindicated. So what do we do?
There are some diets available that have been made to have normal protein levels and also be restricted in phosphorus. Medi-Cal Feline Mature is one such diet, where the manufacturer has recognized the need for a good quality maintenance diet that has lower levels of phosphorus. As a bonus, it is reasonably price. This is the recommended diet for all cats with early renal disease, and may be all that is required to keep the blood phosphorus levels normal, at least in the beginning. As the disease progresses, a food with mild protein levels might be indicated, such as Iams Renal Health. I do not recommend very protein-restricted foods until late stage disease.
Early in the course of this disease we want to increase voluntary water consumption. Cats are little desert critters, and think that they can get away with drinking very little. In most cases they can provided their kidney function is excellent. The problem with our renal cats is that their kidney function is poor, so they can't retain water in the body. We need to encourage water drinking to maintain normal hydration.
1. Water fountains: Many cats love to drink from running water. The commercially available water fountains provide a little stream in the home, and many cats will drink more water simply because they have a continuous source of running water available.
2. Plates: Some cats really like to drink from broad, flat surfaces rather than putting their faces in a bowl and having their whiskers touched by the edges. Think of a lion drinking from a water hole, and you get the idea. Providing a plate filled to the edge with water does the trick for some cats.
3. Adding water to canned food: You can make canned food soup by adding water to the meals.
4. Tuna water: put 1 can of tuna and 1 liter of water in the blender and do that blender thing. Pour into ice cube trays and freeze (just to keep the tuna from going bad). Thaw as needed.
If your cat is eating a good quality canned food, and in reasonable amounts, she should be getting a balanced diet. However, some cats do not eat well, or are vomiting, or are urinating a lot and losing water-soluble vitamins. In these cases I recommend a good multivitamin made for cats (very important). An excellent multi-vitamin is Nu-Cat by Vetriscience.