Unfortunately this is not the case, because there is a lot more to therapeutic CKD diets than reduced protein and/or low phosphorus levels. Staged management of chronic kidney disease in dogs and cats Polzin D, Presentation to the World Small Animal Veterinary Association World Congress says “A common misconception is that renal diets are simply “low protein diets.” Renal diets encompass a variety of modifications beyond just a limitation of protein content, and, indeed, the principal beneficial effects of these diets may not accrue from their protein content. Thus, simply replacing a renal diet with a standard manufactured diet that is lower in protein content does not meet the guideline of feeding a renal diet. Since inappropriate diets can exacerbate clinical signs of uremia and/or promote progression of CKD, cats and dogs with CKD should be fed a renal diet.”
Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal of the American Veterinary Medical Association 229 pp949-57 was a double-blinded randomised study which found that feeding a therapeutic kidney diet helped to keep BUN levels lower and appeared to help prevent metabolic acidosis in cats with more advanced CKD. The study concluded “The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renal-related deaths in cats with spontaneous stage 2 or 3 CKD.” By Stages 2 and 3, they are referring to cats with creatinine between 2.1 and 4.5 mg/dl or 185 and 400 µmol/L (which is not exactly the same range as the IRIS staging system). In this two year study, 22% (five) of the cats eating a standard commercial food died, but none died in the group eating a therapeutic kidney diet. The therapeutic food used (Hill’s k/d) contained 28% protein and 0.5% phosphorus on a DMA basis, while the non-therapeutic food contained 46% protein and 0.9-1.0% phosphorus on a DMA basis. The cats were deemed to be eating the therapeutic kidney diet if 85% of their food intake came from this source. Despite the differences in the phosphorus levels in the foods, there was no difference in parathyroid hormone levels between the two groups of cats.
In one older study, Survival of cats with naturally occurring chronic renal failure: effect of dietary management Elliott J, Rawlings JM, Markwell PJ, Barber PJ Journal of Small Animal Practice 41 pp235-42, 29 cats were fed a reduced protein, low phosphorus therapeutic kidney diet, while a further 21 cats did not eat this diet. Some of the cats (presumably in both groups) were also given phosphorus binders. The cats fed the therapeutic kidney diet survived longer than the other cats, but it is not clear whether this was due to the reduction in phosphorus intake rather than the reduction in protein intake. The study concluded “Feeding a veterinary clinical diet (with intestinal phosphate binders where necessary) specifically formulated for feline renal failure was associated with a highly significant beneficial effect on survival of cats presenting with naturally occurring stable CKD. This is the first prospective dietary study involving naturally occurring feline CKD cases where survival from first diagnosis has been assessed.”
Number two is protein content. An ideal diet for a cat with renal disease should have a highly digestible, bio-appropriate protein content, such as rabbit and poultry. Many of the toxic products that accumulate in the blood in renal failure are a result of protein breakdown. Clinically we find that our raw fed renal cats do well on highly digestible proteins like rabbit, chicken, hare and possum. Too little protein in the diet can lead to excessive weight loss that can be extremely detrimental to a cat's general health. Cats find low protein diets less palatable and often moving a cat to a raw, high quality protein diet from a renal prescription diet leads to improved appetite.
Another thing to consider when deciding when to introduce a therapeutic kidney diet is your cat’s BUN (urea) level. BUN is influenced by protein intake, so it does often help the cat feel better if you restrict protein intake as the CKD progresses. Generally speaking, once BUN levels are over 60 mg/dl (urea over 21 µmol/L), you are more likely to see symptoms such as vomiting and nausea and a therapeutic diet may help with this. The study that most experts cite when recommending a therapeutic kidney diet is Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal of the American Veterinary Medical Association 229 pp949-57. This study found that feeding a therapeutic kidney diet helped to keep BUN levels lower and appeared to help prevent metabolic acidosis in cats with more advanced CKD. The study concluded “The renal diet evaluated in this study was superior to an adult maintenance diet in minimizing uremic episodes and renal-related deaths in cats with spontaneous stage 2 or 3 CKD.” By Stages 2 and 3, they are referring to cats with creatinine between 2.1 and 4.5 mg/dl (165 – 400 µmol/L international).
A later study, Retrospective study of the survival of cats with acquired chronic renal insufficiency offered different commercial diets Plantinga EA, Everts H Kastelein AM & Beynen AC Veterinary Record 157 pp185-187, looked at CKD cats who had been fed therapeutic kidney diets (seven different foods were fed during the study). The cats fed a therapeutic kidney diet survived for more than twice as long as the cats given non-therapeutic diets (16 months versus 7 months). The diet fed to the cat who survived the longest (23 months) contained a relatively high level of essential fatty acids (the food in question was apparently Specific Kidney Support). In this non-randomised, non-double-blinded study, the cats could be fed a non-therapeutic diet for up to 25% of the time.
I appreciate your tutorial, but I have several questions and comments.
I did not see a weight or measure for the chicken so it would be helpful to how what the quantity is (lbs/ounces) per batch.
It would be helpful to know how many servings one batch makes (assuming an average 8 lb cat).
I also agree with the comment below that baking soda is NOT the same as calcium carbonate. Calcium carbonate would be used to add calcium to the food. The only reason I can think of to add baking soda (sodium bicarbonate) to the food would be to help counteract an acidic condition in the cat since baking soda is alkaline. 1/8 tsp of baking soda contains 160 mg sodium and 1/8 tsp salt contains 250 mg sodium. Chicken also contains some naturally occurring sodium so it's hard to tell how much sodium would be in each serving. If calcium isn't added to the batch then it seems like it would be lacking in calcium (it also helps helps counteract phosphorus). I would caution anyone thinking of using this recipe to ask their vet about the use of baking soda in it instead of calcium carbonate before they try it on their cat(s).
You said that your recipe called for canola oil, but instead you are using chicken fat. UC Davis' Veterinary Medicine Nutritional Support Service, uses corn oil in their prescription diet recipes because it is rich in the essential fatty acid, linoleic acid. They say; "Other fat sources (canola oil, butter, etc.) are lower in linoleic acid, and larger amounts are needed to meet this requirement. These fat sources are sometimes used in diet formulations with higher fat levels, but ingredients are not directly interchangeable due to the variation in fatty acid content." Unless canola or corn oil are organic they are gmo, so I wouldn't use them. Safflower oil is higher in linoleic acid than corn oil, so I might use organic cold pressed safflower oil. But I'd also want to use Nordic Naturals Omega-3 for pets to insure adequate omega 3 fatty acids.
Because I am not comfortable with the ingredients in my cat's commercial prescription diet food I am interested in making the food myself, but I don't want to cause more harm to my cat than good. For additional guidance I found the BalanceIT website which was founded by a board certified veterinary nutritionist. You can play around with their free 'Autobalancer' tool to add ingredients that you want in your cat's food and then you can print out a balanced recipe that uses their complete vitamin/mineral supplement (UC Davis uses it too). If you want use their 'Free Recipe Generator' which will generate a renal diet for your cat based on age, weight, health conditions, etc., they will contact your vet for permission to do so and then their veterinary nutritionist will help you with that. Their renal diet uses their BalanceIT Feline K vitamin/mineral supplement which is low in phosphorous and sodium and higher in potassium and other nutrients CKD kitties need.
The International Renal Interest Society divides CKD into stages (see How Bad is It?) and suggests starting a veterinary diet in Stage 2, i.e. when the cat’s creatinine is over 1.6 mg/dl or 140 µmol/L. However for cats with proteinuria, it states “feed a renal clinical diet” regardless of the stage the cat is in. It also says that introducing a therapeutic diet “may be accomplished more easily early in the course of CKD, before inappetance develops.”