Hill’s Prescription Diet

Review Details
Website Hill’s Prescription Diet
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Hill's Prescription Diet

Hill’s Prescription Diet

There’s a lot of controversy about corporate manufacturer Hill’s. Vets endorse it and many would seemingly defend it to their graves, but many pet nutritionists and prominent social media figures in the pet space such as Dr. Karen BeckerRodney Habib, and the Truth About Pet Food’s Susan Thixton are actively against it.

My first cat died on Hill’s Prescription Diet k/d as recommended by a vet who’s professional knowledge I trusted. Years of involvement in pet food, pet food marketing, and discussions with consumers, vets, veterinary professors, and manufacturers has helped me understand the two sides of debate. I’ve drawn my own conclusions which I’ll explain pragmatically, but given what I know now, if my present cat was suffering the same condition then Hill’s Prescription Diet would be the last product I feed. If you read this full review you will come to understand why.

For simplicity I will focus on k/d, but the same applies to all prescription diets in the Hill’s range.

I’ll start with a simple undisputable fact about the food – The main and most prominent ingredient is rice. The second ingredient is corn gluten meal. These two ingredients amount to the bulk of the food, which is sold as a diet for a carnivorous animal. It also contains wheat and wheat gluten. Let that sink in for a moment…

Let’s consider two of the most common arguments pro-Hill’s from veterinary professionals:

(1) Scientific studies show a cat with renal failure on a renal prescription diet can live up to twice as long.

(2) Scientific studies show the improvement in renal parameters on bloodwork when fed a renal diet prescription diet.

These are correct, but the reason why they’re correct is rarely considered. Vets rarely question a cause, only offer what they believe is best as a solution. With any dietary related condition, the first question a vet should be asking is “What was their previous diet?“. Most of these studies show an improvement based on a cat being fed one of the many commercial diets formulated from cereals and cereal grains (such as wheat), which means they will almost certainly show improvement when switched to a diet formulated on rice and corn. It doesn’t detract from the fact it is still the wrong diet for a carnivore, and the previous diet (of cereals and cereal by-products) was likely the cause of the condition in the first place.

In any case, a cat with a renal condition should never, under any circumstances, be recommended a dry diet absent of moisture.

To further support the pro-prescription diet argument, a food such as k/d is formulated with reduced phosphor which is a requirement for a cat suffering a renal condition. Many pet foods, even the better ones, are higher in phosphor. Pet foods with meat meals (comprising of carcass) won’t work for a cat suffering a renal condition. Renal diets are also restricted protein, but I task anyone finding research which proves this to be necessary (other than research conducted on rats almost a century ago).

The other side of the debate is this – a cat (or dog) suffering a condition such as CKD, would be far better off fed a properly formulated and considered fresh diet. This is 100% true, but the reality is it’s a difficult thing to achieve which requires research and a sound knowledge of feline nutrition. Because of this, a prescription diet is the safest diet a vet can recommend for a cat (or dog) suffering a specific condition.

We rate this food at 2 star because rice and corn is not an appropriate diet for a carnivore. It is, however, better than any of the main/supermarket brand cat foods formulated with cereals such as wheat. We need to stop feeding our pet carnivores grains.

If you’re feeding your cat a Hill’s Prescription food for your cat and you’re uneasy about switching to a fresh diet, then at least opt for Hill’s Prescription wet food as the better alternative to a processed dry grain-based food.

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Guaranteed Analysis

* Carbohydrates aren’t listed on pet food labels. This value is calculated based on levels of protein, fat, moisture, and ash. Estimated values for moisture and ash have been used where these values haven’t been given (moisture of 10%, and ash of 8%).


Brown Rice, Corn Gluten Meal, Chicken, Pork Fat, Whole Grain Wheat, Cracked Pearled Barley, Wheat Gluten, Chicken Liver Flavor, Pea Protein, Egg Product, Fish Oil, Lactic Acid, Potassium Citrate, Calcium Sulfate, L-Lysine, L-Arginine, Choline Chloride, Calcium Carbonate, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Niacin Supplement, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Pyridoxine Hydrochloride, Biotin, Vitamin B12 Supplement, Riboflavin Supplement, Folic Acid, Vitamin D3 Supplement, Menadione Sodium Bisulfite Complex (source of Vitamin K)), L-Threonine, Taurine, Iodized Salt, DL-Methionine, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), Potassium Chloride, L-Carnitine, L-Tryptophan, Mixed Tocopherols for freshness, Natural Flavors, Beta-Carotene.