Rating: 
Hill’s Prescription Diet R/D Canine dry dog food gets the Advisor’s second-lowest rating of two stars.
The Hill’s Science 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.
- Hill’s Prescription Diet R/D Canine Weight Loss
- Hill’s Prescription Diet R/D Canine Weight Loss 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: Ground whole grain corn, corn gluten meal, chicken by-product meal, soybean mill run, powdered cellulose (source of fiber), soybean meal, chicken liver flavor, dried beet pulp, soybean oil, carmel color, dl-methionine, l-lysine, potassium chloride, vitamin E supplement, 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), iodized salt, minerals (manganese sulfate, ferrous sulfate, zinc oxide, copper sulfate, calcium iodate, sodium selenite), calcium carbonate, taurine, l-carnitine, preserved with mixed tocopherols and citric acid, beta-carotene, rosemary extract
Fiber (estimated dry matter content) = 13.1%
Red items when present indicate controversial ingredients
The first ingredient in this dog food is corn. Now, contrary to what you may have heard, corn isn’t necessarily a bad ingredient.
On the other hand, although there’s no way to know for sure here, the corn used in making many pet foods can be similar to the kind used to make feed for livestock.
And that can sometimes be problematic.
What’s more, corn is commonly linked to canine food allergies1.
For these reasons, we rarely 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 (the good stuff) washed out of it.
Compared to meat, glutens are inferior grain-based proteins low in many of the essential amino acids dogs need to sustain life.
This inexpensive plant-based ingredient can significantly boost the total protein content reported in 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”.
This stuff can contain almost anything… feet, beaks, undeveloped eggs… everything but skeletal muscle (real meat).
On the brighter side, by-product meals are meat concentrates and contain nearly 300% more protein than fresh chicken.
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 cotton or sawdust. Cellulose is sometimes added to dilute the number of calories per serving and to give the feeling of fullness when it is eaten.
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 actually a useful by-product. It’s what remains of soybeans after all the oil has been removed.
Soybean meal contains 48% protein. However, compared to meat, this is an inferior plant-based protein. So, we must allow for this boosting effect as we judge the meat content of this 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 soybean oil… red flagged here only due to its suspected (yet unlikely) link to canine food allergies.
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 two notable exceptions…
First, we find no evidence of probiotics… friendly bacteria applied to the surface of the kibble after processing.
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
Even though this is a prescription product, we continue 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…
This “professional” weight loss product is a real disappointment. That’s because 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 34%, a fat level of 8% and an estimated carbohydrate content of 49%.
The two products feature an average protein content of 34.5% and an average fat level of 8.5%. Together, these figures suggest a carbohydrate proportion of 49% for the overall product line.
Above-average protein. Low fat. And average carbohydrates… when compared to a typical dry dog food.
Yet when you consider the protein-boosting effect of the soybean and corn gluten meals, this looks like the profile of a dry dog food containing only a moderate amount of meat.
Plus it’s difficult to ignore the unwelcome presence of so many Red Flag items.
Bottom line?
Hill’s Prescription Diet R/D Canine is a plant-based dry dog food using a moderate amount of chicken by-product meal as its main source of animal protein… thus earning the brand two stars.
Not recommended.
Those looking for a comparable weight loss product from the same company may wish to visit our review of Hill’s Prescription Diet W/D dry dog food.
A Final Word
This review is 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 analyzed this product, please be sure to 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 veterinarian for help.
Have an opinion about this dog food… or maybe the review itself? Please know… we welcome your comments.
Notes and Updates
01/02/2010 Original review
08/08/2010 Review updated
- White, S., Update on food allergy in the dog and cat, World Small Animal Veterinary Association, Vancouver, 2001 ↩
The Dog Food Advisor publishes independent reviews to help pet owners make better choices when shopping for dog food.