RenalTech™ – The Mars / VCA Kidney Test Algorithm

Ron Hines DVM PhD

In the late 1980s, veterinarians at Minnesota, College of Veterinary Medicine published a study that indicated that a low protein low phosphorus diet for dog’s slowed the progress of kidney failure. (read here)  Nine years later, another group ran a similar study in cats and reported that low protein, low phosphorus diets did not extend the lives of cats with kidney disease nor did they  extend the lives of dogs with progressive kidney failure. (read here & here) Over the years, the prevailing opinion became that if low protein diets were at all helpful for dogs and cats with kidney disease, it was probably the lower phosphorus that was beneficial. 

You might help solve this controversy. 

In 2020 Antech Diagnostics, a division of  Mars Conglomerates saw an opportunity and introduced their RenalTech™ algorithm. It compares your cat’s age with its blood creatinine level and several other blood values and furnishes a decision that they claim to be 95% accurate at predicting when your cat’s kidneys will begin to fail. See an example of that here: Not a coincidence, Mars also markets the lower phosphorus prescription diet for cats, Renal Support A and S. Compared to their standard formula dry cat food, in the first they have dropped the phosphorus and protein content slightly by adding more fat. In the second they they dropped the protein and phosphorus content even more through the same method.  Let me know how your cat  likes this food.  Did your cat’s blood phosphorus or creatinine level dropped after being on the diet for a month? In What part of the USA or the world do you and your cat reside? I will post that information here. Thanks, R.S.H.


September 23, 2020

My cat won’t eat wet food [he insists on dry kibble]. He was willing to eat Royal Canin A for 6 months, and then wouldn’t. He ate Royal Canine S for a while and then stopped. He now likes Purina NF and Blue Buffalo Kidney and Mobility. I mix them to make a new ratio for variety–some days 80% NF to 20% Blue, some 90/10. The calories per cup are very different. I favor the Purina NF. [When he gets tired of one I ] start over.

RC A is 0.6% maximum phosphorus. Royal Canine S is 0.55 maximum phosphorus. Purina NF is 0.44 maximum phosphorus. Blue Buffalo K+M is 0.4% minimum phosphorus. The bags of BB K+M with a vertical orange strip are 0.7% maximum phosphorus. I wrote to them, BB said they use a 0.4% minimum to 0.7% maximum because they can’t accurately tell the phosphorus level other than by testing each batch. Its said, probably by the renal cat food manufacturers, that if a cat eats a renal diet at about .5 % Phosphorus vs. 1 to 3 percent in a commercial food, a binder may not be needed. Fancy Feast is around 2 percent. My cat’s blood phosphorus level tested at 4.1 once and at 4.6 once while on the renal diets.

I prefer giving the 200 mg Con Seal AIH phosphate binder because it is chewable while Phos-Bind powder from Rx Vitamins being a powder is hard to get to stick on his kibble. My vet suggested lanthanum, phosphate binder. I found one article that says lanthanum can bind/stick to arteries–just one mention of this. Most people in the group use Phos- Bind. Some use Epakitin. Epakitin is calcium based [possibly a bad thing?]. If and when I use a PB I will give the least amount possible using P testing and panels every 3 months. wise. The Antech phosphorus scale upper limit is far over the IRIS recommendation of treating at 4.0 and 4.6 P in CKD cats. Antech’s P normal or typical range is: 2.4 to 8.2 P !!! 8.2 is far above 4 to 4.6 for use of a binder. Vets and owners could miss that. 

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