Hills Prescription Diet Dog Food Reviews

Hill’s Prescription Diet has 2 lines of dog food. There is a line of dry dog foods with 27 recipes, and 1 line of canned dog foods with 32 recipes. It’s concerning that the average score of the dry dog foods is 1.6/10 by our criteria, so they score very low in ingredient quality and ingredient safety, and are considered very high risk. The average score for the wet recipes is only marginally better at 2.8/10 so they’re considered high risk dog foods. This is disturbing given these brands are marketed to support various health issues in dogs.

The Hill’s Prescription Diet website speaks in broad terms about nutrition for a range of health conditions that include urinary, kidney, skin, heart, digestive and dental care and weight management. However, it doesn’t go into detail or name specific ingredients to address these concerns for the pet owner who might want to know how these foods will specifically help their pets. It directs pet owners to their veterinarian, who must prescribe/recommend the food.

It’s worth noting that the FDA practices “enforcement discretion” and has not reviewed or verified the health claims on veterinary diets. Conversely, non-prescription pet store dog food with a health claim (such as weight management) is subject to FDA regulations and enforcement. 

These foods state that they’re complete and balanced, but not all veterinary diets meet AAFCO standards for complete and balanced daily feeding. The FDA allows this exception when diets are sold through veterinarians because vets can provide appropriate guidance to the pet owner. Most veterinary diet packaging will contain instructions to follow your veterinarian’s feeding instructions. However, this could mean that some veterinary diets may not meet a dog’s nutritional needs over the long term, even if they help with the disease the food is intended to manage.

It’s worth explaining about ingredient splitting early in this review. This is a technique of manipulating the ingredient list to move certain ingredients higher or lower on the ingredient list. Most of these recipes use ingredient splitting with quite a few using it in the first 5 ingredients listed. You’ll see various forms of potato, rice or corn so when combined, they push the single protein further down the list and the starches higher. This is also reflected in the excessively high level of carbohydrates found in all of these recipes. Starchy ingredients like soybean, oats, pea fiber, wheat and sorghum are also found in the top 5-8 ingredients.

More than half of the dry recipes have average carbohydrates in excess of 50% as calculated. The canned foods have excessively high levels of carbs with an average of 54% as calculated, exceeding the dry foods. Normally canned foods are lower in starches and grains as they aren’t required for the extrusion process used to make dry foods. 

Dogs have no nutritional requirement for carbohydrates. Starch is also required for extrusion in dry foods. Excessive carbohydrate is an indicator of food quality as it can be used to reduce manufacturing cost. Foods that are high in carbohydrate can raise insulin and cause obesity. In fact, dogs have only one hormone to reduce excessive amounts of glucose in the bloodstream from carbohydrates, while they have 8 hormones to raise glucose levels in times of famine. Some studies also show that dogs fed a high carbohydrate content have changes to their gut bacteria.

The U/D Dry Dog Food recipe has 79% carbs and excessively low protein of 10% in a food prescribed for urinary issues. In fact, dogs with kidney or urinary issues require quality protein that is easily digested, rather than cheap, limited amounts of animal protein or plant protein that’s harder to digest. One food has no animal source of protein except for egg “product.”

There are 2 very similar wet diets of cornstarch, chicken fat, sugar and cellulose with pork liver and egg “product” as the top 6-7 ingredients, with very low protein of 8-13%. They have 2-3 times as much fat as protein and carbohydrates of 55-60% as calculated. Chicken fat is high in omega-3 fatty acids and is highly inflammatory. These recipes are labeled for urinary care and heart care. What is also concerning is that dogs with urinary problems usually require higher levels of fluids, which is lacking in a dry food diet. 

There are recipes for dogs with skin issues, which are high in inflammatory fat like chicken fat, but they don’t have omega-3s that would aid skin health. The Digestive Health dry recipe has 65% carbs as calculated, and includes sugar, dextrose, chicken and rice, which are high in calories and have been found to be inflammatory and not the best for digestive issues. 

It’s concerning that the Joint Health recipe has flaxseed combined with high levels of corn, an inflammatory ingredient that affects joint health. There are a few allergy recipes with single proteins but they have potatoes, several grains, cellulose, soybean oil and cornstarch, which are common allergens. One weight control recipe lists liver and chicken followed by high calorie,  starchy carbohydrates like corn and rice, and then fillers that include cellulose and industry waste like beet pulp and tomato pomace.

Both lines of dry and wet foods are noticeably lacking whole food ingredients like fruits and vegetables. Usually after the first 10-12 ingredients which are mainly grains along with sugar, cellulose and some protein, a substantial list of synthetic vitamins, minerals and amino acids follow. One exception is that in most dry foods and one of the wet foods (Derm Complete), peas, carrots, cranberries, apples, broccoli and zucchini have been added. Unfortunately, these are glam ingredients and are found so low on the list that they contribute no nutritional value. Whole food ingredients like fruits and vegetables would provide much-needed antioxidants, and provide a natural source of vitamins and minerals rather than relying on synthetic forms that are less digestible and bioavailable to dogs. 

Fruits and vegetables would also provide soluble fiber rather than using powdered cellulose, an insoluble fiber made from wood pulp. It’s the least expensive and least functional form of fiber since it’s very poorly fermented. 

Hill’s Prescription Diet uses ground pecan shells, dried beet pulp, tomato pomace and soybean mill run, which are low quality, waste products from manufacturing. There are studies about the antioxidant content of pecan shells, but the fact remains, these recipes lack whole food ingredients that would provide more substantial sources of soluble fiber, antioxidants and natural vitamins and minerals, rather than obtaining them from cheaper sources and industry waste.

Most recipes also have added amino acids, which indicates there’s less animal protein and more plant protein in the recipes. Other ingredients that raise quality concerns include the use of sugar that dogs don’t need, added color and heavily processed, inflammatory seed oils like soybean oil.

Like all dry dog foods, these are ultra processed, with several stages of heating that causes a loss of nutrients. Canned foods are less processed but still involve several stages of heating.

When it comes to ingredient safety, both lines include ingredients known to have high pesticide or herbicide residues, and some known to be genetically modified (GMO). Pesticides, herbicides and fertilizers post a significant health risk to plants, animals and soils. GMO foods have limited safety studies and they lack nutrients compared to non GMO foods. Another safety concern is the use of rice that can be contaminated with arsenic, which is linked to chronic health issues.  

Hill’s doesn’t state whether fish or fish oil is from farmed or wild caught sources. Wild caught fish is more nutritious and has a better fatty acid balance providing healthy omega-3s. Hill’s doesn’t state the omega-6:omega-3 ratio in their recipes. While this is true of most companies, it’s a concern because AAFCO allows a very inflammatory ratio of 30:1.

Hill’s dog foods are manufactured in their own facilities in Topeka, Kansas with ingredients from North America, Europe and New Zealand, but detailed sourcing information does not appear to be on the website.

The average score of Hill’s Prescription Diet foods and each sub-brand are listed below. Click on any line to view the individual foods and scores.