Rating: 
Hill’s Prescription Diet R/D Canine dry dog food receives the Advisor’s second-lowest tier rating of 2 stars.
The Hill’s Prescription Diet R/D Canine product line lists two dry dog foods.
Although each formulation appears to be designed for adult weight loss, we found no AAFCO nutritional adequacy statements for these dog foods on the Hill’s website.
The following is a list of recipes available at the time of this review.
- Hill’s Prescription Diet R/D Canine Weight Loss Low Calorie
- Hill’s Prescription Diet R/D Canine Weight Loss Low Calorie with Chicken
Hill’s Prescription Diet R/D Canine Weight Loss dry dog food was selected to represent both products for this review.
Hill's Prescription Diet R/D Canine Weight Loss
Dry Dog Food
Estimated Dry Matter Nutrient Content
Ingredients: Whole grain corn, corn gluten meal, chicken by-product meal, soybean mill run, powdered cellulose, soybean meal, chicken liver flavor, dried beet pulp, lactic acid, soybean oil, caramel color, dl-methionine, l-lysine, potassium chloride, vitamin E supplement, choline chloride, vitamins (l-ascorbyl-2-polyphosphate (source of vitamin C), vitamin E supplement, niacin, thiamine mononitrate, vitamin A supplement, calcium pantothenate, biotin, vitamin B12 supplement, pyridoxine hydrochloride, riboflavin, folic acid, vitamin D3 supplement), calcium carbonate, iodized salt, minerals (manganese sulfate, ferrous sulfate, zinc oxide, copper sulfate, calcium iodate, sodium selenite), taurine, l-carnitine, preserved with mixed tocopherols & citric acid, phosphoric acid, beta-carotene, rosemary extract
Fiber (estimated dry matter content) = 13.1%
Red items when present indicate controversial ingredients
| Estimated Nutrient Content | |||
|---|---|---|---|
| Method | Protein | Fat | Carbs |
| Guaranteed Analysis | 35% | 8% | NA |
| Dry Matter Basis | 35% | 8% | 49% |
| Calorie Weighted Basis | 33% | 19% | 47% |
The first ingredient in this dog food is corn. Corn is an inexpensive and controversial cereal grain of only modest nutritional value to a dog.
For this reason, we do not consider corn a preferred component in any dog food.
The next item is corn gluten meal. Gluten is the rubbery residue remaining once corn has had most of its starchy carbohydrate washed out of it.
Compared to meat, glutens are inferior grain-based proteins lower in some of the essential amino acids dogs need for life.
This inexpensive plant-based ingredient can significantly boost the total protein reported on the label — a factor that must be considered when judging the actual meat content of this dog food.
The third item reports chicken by-product meal, a dry rendered product of slaughterhouse waste. It’s made from what’s left of a slaughtered chicken after all the prime cuts have been removed.
In a nutshell, chicken by-products are those unsavory leftovers usually considered “unfit for human consumption”.
In addition to organs (the nourishing part), this stuff can contain almost anything — feet, beaks, undeveloped eggs — anything except quality skeletal muscle (real meat).
On the brighter side, by-product meals are meat concentrates and contain nearly 300% more protein than fresh chicken.
In any case, although this item contains all the amino acids a dog needs, we consider chicken by-products an inexpensive, lower quality ingredient.
The fourth item lists soybean mill run. Mill run is a by-product, mostly the hulls of soybeans remaining after processing the beans into meal. This is nothing more than a cheap, low-quality filler more commonly found in cattle feeds.
The fifth ingredient is powdered cellulose, a non-digestible plant fiber usually made from the by-products of vegetable processing. Except for the usual benefits of fiber, powdered cellulose provides no nutritional value to a dog.
The sixth ingredient is soybean meal. Soybean meal is relatively useful by-product — what remains of soybeans after all the oil has been removed.
Although soybean meal contains 48% protein, this ingredient would be expected to have a lower biological value than meat.
And less costly plant-based products like this can notably boost the total protein reported on the label — a factor that must be considered when judging the actual meat content of this dog food.
After the chicken liver flavor, we find beet pulp. Beet pulp is a controversial ingredient, a high fiber by-product of sugar beet processing.
Some denounce beet pulp as an inexpensive filler while others cite its outstanding intestinal health and blood sugar benefits.
We only call your attention here to the controversy and believe the inclusion of beet pulp in reasonable amounts in most dog foods is entirely acceptable.
The ninth ingredient is lactic acid, a nutrient found naturally in many living organisms.
It’s difficult to say with certainty why lactic acid is present here except to presume it’s added to balance the pH of the recipe.
The tenth ingredient is soybean oil is red flagged here only due to its rumored (yet unlikely) link to canine food allergies.
However, since soybean oil is high in omega-6 fatty acids and contains no omega-3′s, it’s considered less nutritious than flaxseed oil or a named animal fat.
From here, the list goes on to include a number of other items.
But to be realistic, ingredients located this far down the list (other than nutritional supplements) are not likely to have much of an effect on the overall rating of this product.
With three notable exceptions…
First, we find no evidence of probiotics, friendly bacteria applied to the surface of the kibble after processing.
Next, caramel is a coloring agent made by caramelizing carbohydrates. It’s used by pet food manufacturers to impart a golden brown tint to a finished kibble.
Even though caramel is considered safe by the FDA, we’re always disappointed to find any added coloring in a pet food.
That’s because coloring is used to make the product more appealing to humans — not your dog. After all, do you really think your dog cares what color his kibble is?
Finally, the minerals here do not appear to be chelated. And that can make them more difficult to absorb. Non-chelated minerals are usually associated with lower quality dog foods.
Hill’s Prescription Diet R/D Canine Dry Dog Food
The Bottom Line
Because this is a prescription product, we are compelled to limit our judgment to the estimated meat content of the recipe as well as the apparent quality of its ingredients. And nothing else.
Our ratings have nothing to do with the accuracy of claims made by the manufacturer as to this product’s ability to effectively treat or cure a specific health condition.
So, to find out whether or not this dog food is appropriate for your particular pet, you must consult your veterinarian.
With that understanding…
Judging by its ingredients alone, Hill’s Prescription Diet R/D Canine appears to be a below-average dry dog food.
But ingredient quality by itself cannot tell the whole story. We still need to estimate the product’s meat content before determining a final rating.
The dashboard displays a dry matter protein reading of 35%, a fat level of 8% and an estimated carbohydrate content of 49%.
The two products feature an average protein content of 35% and an average fat level of 9%. Together, these figures suggest a carbohydrate proportion of 49% for the overall product line.
And a fat-to-protein ratio of about 25%.
Above-average protein. Below-average fat. And near-average carbs when compared to a typical dry dog food.
Yet when you consider the protein-boosting effect of the corn-gluten meal and all the soy products, this looks like the profile of a kibble containing only a limited amount of meat.
Bottom line?
Hill’s Prescription Diet R/D Canine is a plant-based dry dog food using a limited amount of chicken by-product meal as its main source of animal protein, thus earning the brand 2 stars.
Not recommended.
Special Alert
Rice ingredients can sometimes contain arsenic. Until the US FDA establishes safe upper levels for arsenic content, pet owners may wish to limit the total amount of rice fed in a dog's daily diet.
A Final Word
The descriptions and analyses expressed in this and every article on this website represent the views and opinions of the author.
Although it's our goal to ensure all the information on this website is correct, we cannot guarantee its completeness or its accuracy; nor can we commit to ensuring all the material is kept up-to-date on a daily basis.
Each review is offered in good faith and has been designed to help you make a more informed decision when buying dog food.
However, our rating system is not intended to suggest feeding a particular product will result in specific health benefits for your pet.
For a better understanding of how we analyze each product, please read our article, "The Problem with Dog Food Reviews".
Remember, no dog food can possibly be appropriate for every life stage, lifestyle or health condition. So, choose wisely. And when in doubt, consult a qualified veterinary professional for help.
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Notes and Updates
01/02/2010 Original review
08/08/2010 Review updated
05/23/2012 Last Update
