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 Becker, Rodney Habib, and the Truth About Pet Food’s Susan Thixton are actively against it.
The reason is very simple – Our cats are carnivores, yet Hill’s Prescription Diet dry cat foods are made significantly from grains.
In the Hill’s Prescription Diet cat food review I’ll walk you through the ingredients and composition of one of their formulas so you can easily decide for yourself if it sounds healthy for your cat.
A little background: My personal experience…
When I had my first cat in my 20s I didn’t have a clue what was healthy for him. I fed him a dry food an equally clueless friend recommended, which was easily available at my local supermarket.
At the age of 7 he was diagnosed with early stage kidney failure and our vet recommended Hill’s Prescription Diet k/d. So that’s what we fed him until the day he died.
During that time he became very skinny, frail, and lethargic. For the latter stage of his life he was on other medications, and I vividly remember having to pull his poo out when he had difficulty passing. Like many cat owners, we put it down to “bad luck” or poor old Rodney “getting old”.
We spent a lot of money on the prescription diet and medications because we thought we were doing the best we could for him.
It was a number of years later when, in hindsight, I realised something glaringly obvious – cats are carnivores and the ingredients of Hill’s Prescription Diet is even to this day a lot of grain. Far from what you would expect for a carnivorous animal.
We blindly trusted our vet as a professional, but it is very clear to me now the complex reasons why our vet’s recommend these products. I’ve written more about it here.
If you’re feeding any kind of Hill’s Prescription Diet cat food, or are considering it, then keep reading this review and you can decide for yourself what you think is best for your carnivorous cat.
If you’re still planning to feed a Hill’s Prescription food to your cat, which will very likely be for a specific health reason, then keep reading and I’ll give you a really good tip at the end of the review – so don’t worry if you see Hill’s Prescription Diet as the only option.
Hill’s Prescription Diet review
What the marketing says
Hill’s Prescription Diet, and Hill’s Science Diet, are products of Colgate-Palmolive, a company who have done very well from convincing us their products are necessary for our health and wellbeing.
I shampoo my hair and clean my teeth every day, but do you ever wonder why natives of many countries have amazing hair and teeth without these products?
I’ll put my tin foil hat to one side as I don’t want to go down that rabbit hole, but it’s interesting don’t you think?
What can be said about Colgate-Palmolive and Hill’s is they have an excellent marketing and research budget. In fact the research they fund is very influential in the pet health industry, and also very clever.
Consider this – as a product manufacturer do you think they will fund research to (a) promote their products, or (b) convince you another type of diet is healthier, such as raw or fresh?
I hope that doesn’t sound too radical, but I consider it the reason we feed our meat-eating carnivorous cats hard-baked biscuits made from wheat, rice, or corn. Their scientific studies convince us the only healthy option for our cats is baked grain nuggets.
What do you think?
Science or clever marketing?
If you want more to consider, let’s take a look at the ingredients of Hill’s Prescription Diet based on the well known fact our cats are carnivores…
What the ingredients really say
For simplicity I will focus on Hills Prescription Diet k/d, but the same applies to all prescription diets in the Hill’s range. If you’re feeding something else, for whatever reason, then simply take a quick look at the ingredients before continuing with this review.
Did you read the ingredients? What did you think?
You’ll find chicken as the first ingredient in the formula, but don’t let this fool you. It actually used to be rice first before they tweaked the formula.
Out of the top four ingredients, which may well be in equal proportions, we have one part chicken to three parts grain – brown rice, corn gluten meal, and wholegrain wheat.
Possibly 25% chicken when we consider those 4 ingredients alone, or less if we consider the others.
That’s not the last of the grain either, as brewers rice as the 6th ingredient may amount to almost as much, and we also see wheat gluten in the ingredients as well.
So that’s a lot of grain, for our carnivorous cats?
We can get a little scientific here ourselves, and see how those ingredients tally with the composition – 29.5% protein, 23.7% fat, and listed carbohydrates of 38.2%.
The first point is 38%+ is carbohydrates, arguably redundant for a cat.
The protein of 29.5% may sound good, but we must consider this is protein from all those grains as well as the chicken. Corn, for example, is very high in protein.
That matters when we consider our cats digest protein from meat more effectively than protein from grains.
Cats have a much shorter digestive tract than us, and shorter than dogs, which means they struggle to process grains sufficiently in the time it takes the grains to pass through their digestive system.
When a cat is fed ingredients which aren’t species appropriate it can take a toll on their digestive system and organs, including kidneys (which ironically is what this formula is supposed to address).
We’ve covered the main ingredients in Hill’s Prescription Diet k/d for sick cats, so you’re probably wondering how that can be healthy or appropriate to kidney disease?
So how does it help those cats? Perhaps it’s better than whatever cat food was fed previously which was possibly even more grain, or harsher grains, which may’ve caused the illness in the first place. Maybe the previous food had chemical preservatives and food colourings?
I really wish all vets would consider what a cat was fed prior to their organs starting to fail. Even better, I wish it was a key part of their studies.
It should be, don’t you think?
Let’s consider the “science”…
Let’s wrap up the Hill’s Prescription Diet cat food review with 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 may well be true, or true in edge cases, but they’re overlooking the most critical factor – What was the cat fed previously?
It’s possible the previous diet was the cause of the illness in the first place, and it doesn’t take much for a “prescription” cat food to be an improvement, or show an improvement in blood tests.
Vets rarely question a cause, only offer a form of medication – i.e. an expensive prescription diet like Hill’s Prescription Diet k/d, or a range of expensive medications or treatments.
With any dietary related condition, the first question a vet should ask is what was the cat fed until this point. If your vet doesn’t ask this, you should question why.
Most scientific 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.
Try eating fast food for one month, have your health checked, then only eat microwave ready meals for the next month. Do you think your health would show an improvement?
What about studies which show whether a cat fed a whole prey raw diet is healthier on baked nuggets of rice, corn, and wheat? Why would that be scientifically overlooked?
Well, it wouldn’t help sell the product, would it?
Food for thought?
In my opinion, a cat with a renal condition should never, under any circumstances, be recommended a dry diet absent of moisture.
Which prescription diet should I feed?
One of the most common questions I get asked is which is better, Hill’s (Prescription or Science Diet), or the Royal Canin prescription formulas.
If your cat is suffering a specific illness you are very limited in terms of commercial cat foods.
My best recommendation with both Hill’s and Royal Canin would be their wet food alternatives. For both brands I find these have a much better emphasis on meats and meat proteins, and the moisture content will also be beneficial to your cat over any dry food.
If the wet foods are too expensive, at least have them as part of their diet.
The other option you have is researching a raw or fresh food diet tailored to their health condition. This may also be an option as part of their diet, and may offer your cat better long term health.
Where to buy
For the sake of a price compare the following is for Hill’s Prescription Diet Feline k/d, but should offer a good price guide for different retailers:
Ingredients of Hill’s Prescription Diet cat food (k/d formula):
Chicken, Brown Rice, Corn Gluten Meal, Whole Grain Wheat, Chicken Fat, Brewers Rice, Pea Protein, Chicken Liver Flavor, Powdered Cellulose, Egg Product, Wheat Gluten, Soybean Oil, Fish Oil, Lactic Acid, Calcium Sulfate, Potassium Citrate, L-Arginine, Calcium Carbonate, L-Lysine, Choline Chloride, DL-Methionine, L-Threonine, vitamins (Vitamin E Supplement, Niacin Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Thiamine Mononitrate, Pyridoxine Hydrochloride, Calcium Pantothenate, Riboflavin Supplement, Biotin, Vitamin A Supplement, Vitamin B12 Supplement, Folic Acid, Vitamin D3 Supplement), Taurine, Potassium Chloride, Iodized Salt, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), L-Carnitine, L-Tryptophan, Mixed Tocopherols for freshness, Natural Flavors, Beta-Carotene.
Guaranteed analysis of Hill’s Prescription Diet cat food (k/d formula) based on dry matter:
|Carbohydrates *||38.2% (listed on label)|
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With so many grains in Hill's Prescription Diets for obligate carnivore cats, it really makes you wonder why such a diet would be prescribed or endorsed by vets. Is clever marketing at play? What does the science and research really say?
- Wheat gluten!
- Aren't cats carnivores?