Purina Pro Plan vs. Science Diet: Which Dog Food Is Better?

  • By: Andrew
  • Time to read: 12 min.

Most pet parents have a discerning need to feed their dogs higher quality foods than what is currently available because food affects their physical and mental well-being. Unfortunately, not all dog foods are created the same, which is why it is necessary to choose the best one. This post scrutinizes Purina Pro Plan and Hill’s Science Diet to find out which is better.

Purina Pro Plan is considered the better dog food than Science Diet as it contains more protein in the wet and dry categories and costs less. Both brands offer the same amount of fiber in dry foods, but Purina has slightly more fat. Neither brand is grain-free, but both have variants without grains.

This article compares these two dog food giants in several categories and gives insight into why these brands could meet discriminating pet parents’ standards. If you are considering buying either, read on to check what they can offer before deciding which is better for your dog.

Which Product Is Better: Purina Pro Plan vs. Science Diet?

Both brands employ veterinary professionals to create, develop, and improve their products. That’s probably why veterinarians wholeheartedly endorse and recommend both as providers of healthy balanced dog foods that offer value for money.

Both have similar backgrounds and produce comparable balanced canine diets for various breeds. Their popularity and continued presence in the pet food market are a testament to their commitment to pet health and wellbeing. Although other dog food brands offer more exotic ingredients, Purina Pro Plan and Science Diet provide quality research-backed canine cuisine at a reasonable price.

Despite the merits of both brands, it is important to remember that every dog’s nutritional needs are unique. So it is best to consult veterinarians regarding their diet and medical requirements.

The Comparison Process

Pet parents need to research potential dog foods before making long-term changes in their diet. This can be tricky since the Association of American Feed Control Officials (AAFCO) continually amends its annual pet food nutritional guidelines. (AAFCO is the official regulator of the distribution and sale of animal food and medication.) This move has confused many pet parents trying to select dog food.

To give both contenders a fair trial, we examined each brand’s background, recall history, manufacturing practices, product composition, and the criteria below as bases for comparison:

  • Quality of composition
  • Guaranteed analysis
  • Food safety standards
  • Brand background
  • Price points

Purina Pro Plan Background

Nestlé, based in St. Louis, Missouri, owns Nestlé Purina Petcare, which makes and sells dog and cat food, treats, and cat litter. Purina is the result of a 2001 merger between Friskies Petcare and Ralston Purina. As of 2012, Purina is the largest pet food company in the US and the second-largest worldwide.

Purina claims that 99% of all its Pro Plan recipes are created in the US. It owns and operates all of its production facilities and sources most of its ingredients from local suppliers.

Purina recently changed the names of many of its Pro Plan products and organized its formulas by life stage. Its Pro Plan adult product line has 19 dry dog foods. Each recipe from Purina and Science Diet includes its AAFCO nutrient profile in these categories:

  • Growth (for puppies)
  • Maintenance (for adults)
  • All life stages
  • Supplemental
  • Unspecified

Purina Pro Plan Nutrient Summary

Dog Food Advisor has rated Purina Pro Plan adult dog food as an average dry product based on its ingredient lineup alone. However, it gave Purina an overall four-star rating (above-average).

Chewy customers gave Purina Pro Plan 4.7 stars. Each recipe contains grains, identified meat, and by-product meals.

The nutrient content table below is based on Purina’s Shredded Blend Chicken and Rice product:





Guaranteed Analysis




Dry Matter




Weight in Calories




Fiber = 3.4%

This Pro Plan recipe comprises 30% protein, 18% fat, and 44% carbohydrates. The entire Pro Plan lineup averages 31% protein, 16% fat, and 45% carbohydrates, with a fat-to-protein ratio of about 52%.

Compared to other dry dog foods, Purina Pro Plan has:

  • Almost average fat
  • Above-average protein
  • Below-average carbohydrates

Purina Pro Plan Advantages

  • Veterinarians recommend it.
  • Purina has veterinary nutritionists on staff.
  • The company conducts long-term studies on its products.
  • It performs stringent quality control.
  • Its Pro Plan Focus formula for large breeds has probiotics and glucosamine, a glucose derivative that protects animals and humans from musculoskeletal diseases.
  • Focus also contains fish oil, which promotes brain and vision development.
  • Purina Pro Plan products don’t have bulk fillers like corn, wheat, or other grain types typically found in dog food. These additives are known to cause allergic reactions in sensitive dogs. (However, an industry watchdog has discovered these additives in Purina recipes. See controversial ingredients below.)
  • Purina products are formulated without dyes or artificial colors.
  • Purina is one of the more affordable and nutritionally sound dog food brands available.
  • Dogs fed with Purina kibble produce healthy, solid stools—easier to discard and a sign of proper food clumping.
  • Purina kibble cleans tartar from gums, preventing bad breath.
  • Purina introduced Calming Care, the first and only probiotic tested for canine behavioral change, in January 2019. Many canine probiotics exist, but only for digestive, not behavioral, health.

Purina Pro Plan Disadvantages

  • Persnickety dogs may not like some Purina formulas.
  • Some formulas may affect breath odor.
  • Sensitive dogs may not benefit from the brewer’s rice it contains, as it has minimal nutritional value despite its energy potential from calories.
  • Purina puppy kibble bits may be slightly bigger for tiny dog breeds and are more suitable for older puppies.

Science Diet Background

Hills, the same company responsible for prescription foods, owns Science Diet. Hills operates under the umbrella of the Colgate-Palmolive group. The Science Diet brand is available in 86 countries. Hills claims that veterinarians feed Science Diet pet food to their pets.

The brand started from a formula created by Dr. Mark Morris for a guide dog suffering from kidney failure. His creation was such a success that dog owners discovered and used it as a health supplement to relieve and sometimes resolve some canine medical issues.

Dr. Morris teamed up in the late 1940s with the Hill packaging company to manufacture and package his products. His son developed his original formula into the current Science Diet, which now has 50-plus pet food variants for all life stages and pets with special needs.

Science Diet Ingredients

  • Chicken (primary protein source)
  • Cracked pearled barley (barley without hull and bran)
  • Wheat
  • Corn
  • Sorghum (cereal)
  • Other animal-based ingredients

Science Diet Nutrient Analysis

If an analysis is based on Science Diet’s wet adult dog food’s ingredients alone, it seems like the product is below average. These ingredients include peas, flaxseed, corn, gluten, and soybean meals. With 41% of the total calories from fat and only 25% from protein, some recipes may not be suitable for some dogs.

If only the above factors were considered, then Science Diet’s wet product profile looks like it contains only moderate amounts of meat. However, Dog Food Advisor’s analysis of its dry matter reveals a reading of 30% protein, 21% fat, and 42% carbohydrates.

The entire product lineup shows an average of 26% protein, 18% fat, and 49% carbohydrates, with a fat-to-protein ratio of 69%.

Compared to typical dog foods, Science Diet contains:

  • Almost average protein
  • Below-average fat
  • Above-average carbohydrates

Science Diet Nutrient Summary

Dog Food Advisor used Science Diet’s Adult Savory Stew with Beef and Vegetable recipe as the dry matter basis for their recipe and nutrient analysis below:





Guaranteed Analysis




Dry Matter




Weight in Calories




Fiber = 1.9%

Science Diet Advantages

  • This brand is well-known and has been around since the 1940s.
  • It has a proven history of high-quality pet food creation.
  • It has a wide selection of dog food.
  • Its formulas are scientifically developed.
  • It is one of the best large breed puppy food brands with balanced calcium, chondroitin, and glucosamine, all necessary for bone, joint, and cartilage health.
  • It is famous for producing high-quality kibbles for various dog sizes, including giant breeds like the Great Dane.
  • Its meaty, crunchy kibble morsels have a rough texture that promotes jaw development and prevents tartar build-up on gums—an issue with some large breeds.
  • Veterinarian Michael Hoover recommends Hills because it makes pet food with human-grade ingredients in its own plant. The company also conducts extensive research and has more in-house veterinary nutritionists than its competitors.
  • It offers dry and wet dog foods in varieties based on recipe, breed size, life stage, or medical condition. For example, there is a Science Diet recipe for dogs with sensitive tummies, inadequate oral health, and weight problems.
  • It offers good value for the money.
  • It is available online and in pet stores and vet clinics.

Science Diet Disadvantages

  • It is more expensive than other brands because its formulas are based on scientific research and biologically based nutrition.
  • Dogs sensitive to grains cannot eat their grain-filled recipes. (The brand has grain-free variants, however.)
  • Some of its generic offerings have lower protein levels.
  • It uses some by-products.
  • It supplements its protein with non-meat ingredients.
  • Some testers have noted the minerals listed in Science Diet product labels do not seem to be chelated. Chelated minerals are typically associated with better quality dog foods. Non-chelated substances are more difficult for dogs to absorb.

Comparison of Purina Pro Plan and Science Diet

Conflicting opinions abound in pet forums concerning these brands. (But the same goes for their competitors.) For instance, some folks at MedHelp say they don’t consider Science Diet as one of the better dog foods, although they rate it higher than Purina. They are not happy with Science Diet’s high carbohydrate filler content.

In contrast, pet parents from The Cat Site say Purina contains fewer by-products, so most of them put it above the Science Diet. Also, they claim Science Diet has concentrated animal heads, feet, and intestines, though they did not specify where they got this information.

To be safe, pet parents should check all dog food labels and choose products with the most protein and the least carbohydrates.

Similarities Between Purina Pro Plan and Science Diet

  • Pet nutrition experts consider both brands top-tier with highly regarded histories.
  • Both brands have comparable manufacturing processes.
  • Pet parents of various breeds value both brands highly.
  • Both brands follow AAFCO’s packaging and labeling requirements, particularly with listing the three major components (protein, fat, and fiber) in their food content.
  • Both brands use by-product meals in some of their recipes. These contain unidentified ingredients, such as eggs, beaks, and claws, which are not considered meat nor nutritionally beneficial.
  • Some aggregator websites rate both brands as average dog food producers when it comes to ingredient quality.
  • Both companies’ food products are regularly tested in laboratories and feeding trials following AAFCO standards.
  • Both brands have an adequate track record of offering a well-balanced canine diet that promotes healthy growth and relieves medical issues.

Guaranteed Analysis

According to AAFCO, all pet food should contain guaranteed minimum percentages of crude protein and fat, plus maximum percentages of crude fiber and moisture. All pet food products are required to display this information, which can be found on the back side of the label.

Comparison Chart of Required Percentages

Paw Diet conducted this analysis. All percentages here are averages based on dry matter:

Dry Dog Food

Crude Content

Science Diet

Purina Pro Plan










Wet/Canned Dog Food

Crude Content

Science Diet

Purina Pro Plan










Crude Protein

Protein is responsible for 10 essential amino acids. Dogs need 22 of them for sustenance: 10 are consumed; 12 are synthesized naturally. The table above indicates that Science Diet contains a lot less protein than Purina Pro Plan, with a difference of approximately 7%.

Purina Pro Plan wet dog foods also contain more protein than Science Diet’s wet equivalent.

Crude Fat

Fats are vital to proper growth and biological functioning. Purina Pro Plan contains 3.18% more fat—a slight difference, but still notable. Both brands offer the same amount of crude fiber.

As for wet food, both brands provide approximately the same amount of fat, but Purina Pro Plan offers 3.62% more fiber.

Grain Content

Most of the recipes of both brands contain grain-based ingredients to bolster their protein and fiber content, just like many of their competitors. However, both brands offer specific grain-free variants for dogs with sensitivities, allergies, and intolerances.

The health benefits and disadvantages of grain in canine diets are still under contention.

Controversial Ingredients

Science Diet and Purina Pro Plan both use these controversial ingredients in many of their products:

  • Liver. This organ meat is considered a beneficial component of dog food, but when a product label does not specify from which animal it is sourced, then it is deemed to be controversial.
  • Pea protein. Like all legumes, peas are a great source of carbohydrates and natural fiber. But they contain around 25% protein—a factor nutritionists consider when judging dog food meat content.
  • Brewer’s rice. It often causes allergies and irritations, which manifest in many forms, like diarrhea and skin eruptions.
  • Gluten. It can interfere with nutrient absorption from food, causing symptoms leading to medical conditions like osteoporosis and seizures.
  • Caramel coloring. Its concentrated version has recently been considered controversial because it was found to cause cancer in laboratory animals.
  • Cornmeal. Many dogs have difficulty digesting it.
  • Whole-grain corn and whole-grain wheat. Both contain nutrients valuable to canine diets, but some dogs are allergic to them.
  • Powdered cellulose. In pet food, it’s not the same quality found in human food. Inferior quality cellulose may contribute to shedding, a mark of inflammation.
  • Soybean protein isolate. It should be used with caution in pets with kidney, liver, or thyroid disease because of conflicting evidence about soy protein’s link to cancer.

Harmful Ingredients

Pet food ingredients are classified as harmful when they are connected to negative health effects.

Science Diet and Purina Pro Plan use these toxic ingredients in many of their products:

  • Menadione. Vitamin K3, a synthetic variant of vitamin K.
  • Menadione sodium bisulfite complex. An article published in Truth About Pet Food claims this substance is approved for use only in poultry feed and has never been proven safe for cat/dog food.

Product Recalls

Purina Pro Plan

  • March 9/11, 2016 (Together with Purina Beneful) Faulty reporting of mineral and vitamin content.

Science Diet

Hills issued voluntary recalls of these canned products in 2019:

  • January 31 – Greater than accepted Vitamin D levels in its Prescription Diet and Science Diet products.
  • March 20 – The same recall expanded to include 44 varieties for the same reason.

Earlier recalls include:

  • June 3, 2014 – Science Diet recall
  • November 29, 2015 – Science Diet market withdrawal

Pet Food Types

These are each brand’s product offerings:


Science Diet

Purina Pro Plan

Dry dog food

42 recipes

44 recipes

Wet dog food

34 recipes

66 recipes

Dog treats



Stock Availability

These are the stocks available from their distributors and sellers:

Seller Stocks

Science Diet

Purina Pro Plan


129 recipes

158 recipes


119 recipes

144 recipes

Pet Flow

91 recipes

75 recipes


35 recipes

140 recipes

Price Comparison

Differing moisture levels in each brand’s food products significantly affect the average cost-per-pound. For example, freeze-dried food contains less moisture than dry ones.

Dry Dog Food


Science Diet

Purina Pro Plan

Per pound



Per calorie



Wet Dog Food


Science Diet

Purina Pro Plan

Per pound



Per calorie



Better Value

Industry watchdogs consider both brands average dog food manufacturers when it comes to ingredient and nutrient quality. Despite this average rating, both provide well-balanced cuisine that boosts not only canine health but also addresses medical ailments. Purina Pro Plan, however, is the cheaper of the two, signifying better value.

Final Thoughts

Purina Pro Plan and Science Diet are reputable brands equal in quality. Both their parent companies employ qualified veterinary nutritionists to create their formulas, and they subject their products to feeding trials and lab tests.

Keep in mind, there’s no need to switch brands if your dogs are happy and healthy on what they’re currently eating because swapping foods can cause digestive issues if done abruptly. It’s ultimately up to you and your dog to determine which brand is best.

More about Purina Pro Plan and Purina One

Most pet parents want the best dog food for their canines because food affects their physical and mental well-being. Therefore, I have written a few more articles comparing Purina with other brands on the market.

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