The definition of prescription is an order written by a doctor or veterinarian, in this case, to get a medication that is not available without permission. So, one would assume that a prescription dog food contains a drug or medication only available with a prescription. But that is not the case. Instead, they are called prescription diets because they are formulated to address specific medical conditions. The FDA has no oversight of the diets as they contain no medications. 

Veterinarians typically recommend a prescription or therapeutic diet to manage various health issues, including kidney disease, joint disease, cardiovascular health, <a href="https://feedreal.com/glossary/diabetic-ketoacidosis">diabetes</a>, liver disease, kidney disease, urinary bladder disease, food allergies, <a href="https://feedreal.com/glossary/obesity">obesity</a>, cancer support, and gastrointestinal disorders. Prescription diets contain specialized ingredients and nutrient profiles that can help manage or alleviate the clinical signs of certain conditions. These diets claim to have been developed based on scientific research and clinical evidence and are formulated to provide therapeutic benefits through nutrition. 

This article delves into the ingredients of commonly used prescription diets and compares them to the whole foods recommended for medical conditions. We will also look at a study that analyzed commercial diets formulated as elimination diets for food allergies and intolerances and found that over 89% of the diets studied had false claims about the ingredients in the food. 

Medical Conditions Treated with Prescription Diets 

Prescription diets treat numerous conditions in dogs, including kidney disease, urinary tract problems, food allergies, obesity, and gastrointestinal disorders. Usually, your veterinarian will recommend a product available in the clinic. The FDA does not regulate therapeutic diets, meaning you legally do not need a prescription to obtain the food. Nevertheless, prescription food companies require retailers to receive a written prescription from a veterinarian so that consumers can purchase the prescription diets.

Commercial products are labeled with the ingredients in descending order of quantity. Consumers must rely on labels to determine which foods suit their dogs, especially those with food allergies or intolerances. 

Numerous studies show that <a href="https://feedreal.com/glossary/corn">corn</a>, <a href="https://feedreal.com/glossary/soy">soy</a>, and chicken account for more than 60% of dog food allergens. So, it stands to reason that prescription diets are formulated to avoid common allergens. Yet a look at the ingredient list of a diet commonly prescribed to dogs with allergies shows that this is not the case!

This graph shows the most common allergens in dogs.

 Table 1. Incidence of IgE reactions to food allergens- from Co‐sensitization and cross‐reactivity between related and unrelated food allergens in dogs – a serological study.

Prescription diets designed for elimination trials claim to contain novel protein sources and limited ingredients to help dogs with food allergies or sensitivities. However, studies have shown that many of these therapeutic diets contain ingredients not listed on the label, causing confusion and frustration when determining what foods your dog can tolerate. A benefit of putting your dog's meal together is that you have complete control of what goes into the bowl! There will be no hidden or surprising ingredients to confound results. 

A study that tested dog food ingredients demonstrated that 89% of the foods were mislabeled. Testing one of the foods using DNA sequencing of the ingredients revealed that, despite the producer's declaration that the pet food contained duck and lamb as the two main ingredients, lamb was not detected. Chicken was detected as the second protein source. For diets that are prescribed to avoid specific allergens, the contents must match the label! 

Diet Comparison Hill's Prescription Diet z/d Dry Dog Food (Dog with food sensitivities) 

INGREDIENTS: Corn <a href="https://feedreal.com/glossary/starch">Starch</a>, Hydrolyzed <a href="https://feedreal.com/glossary/chicken-liver">Chicken Liver</a>, Hydrolyzed Chicken, <a href="https://feedreal.com/glossary/powdered-cellulose">Powdered Cellulose</a>, Soybean Oil, <a href="https://feedreal.com/glossary/calcium">Calcium</a> Carbonate, Dicalcium Phosphate, Lactic Acid, Potassium Chloride, Glyceryl Monostearate, <a href="https://feedreal.com/glossary/choline">Choline</a> Chloride, Iodized Salt, vitamins (<a href="https://feedreal.com/glossary/vitamin-e">Vitamin E</a> Supplement, L-Ascorbyl-2-Polyphosphate (source of <a href="https://feedreal.com/glossary/vitamin-c">Vitamin C</a>), <a href="https://feedreal.com/glossary/niacin">Niacin</a> Supplement, <a href="https://feedreal.com/glossary/thiamine">Thiamine</a> Mononitrate, <a href="https://feedreal.com/glossary/vitamin-a">Vitamin A</a> Supplement, Calcium Pantothenate, <a href="https://feedreal.com/glossary/biotin">Biotin</a>, <a href="https://feedreal.com/glossary/vitamin-b12">Vitamin B12</a> Supplement, <a href="https://feedreal.com/glossary/pyridoxine">Pyridoxine</a> Hydrochloride, <a href="https://feedreal.com/glossary/riboflavin">Riboflavin</a> Supplement, <a href="https://feedreal.com/glossary/folic-acid">Folic Acid</a>, Vitamin D3 Supplement), DL-Methionine, Magnesium Oxide, minerals (Ferrous Sulfate, <a href="https://feedreal.com/glossary/zinc">Zinc</a> Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), Taurine, Mixed Tocopherols for freshness, Natural Flavors, <a href="https://feedreal.com/glossary/betacarotene">Beta-Carotene</a>.

Four of the first five ingredients are among the most common allergens for dogs! The rest of the ingredients listed are synthetic vitamins and minerals. This product claims to promote healthy skin and support the immune system. The first ingredient promotes <a href="https://feedreal.com/glossary/inflammation">inflammation</a>, which is the opposite of what your dog with itchy skin needs!

Nutrients that promote skin and immune health include:

A fresh, whole-food diet consisting of muscle meat, raw meaty bones, liver, another secreting organ, small oily fish, and fiber or fur would supply all nutrients essential for healthy skin. 

Suppose your dog is diagnosed with gastrointestinal issues like <a href="https://feedreal.com/glossary/chronic">chronic</a> diarrhea, <a href="https://feedreal.com/glossary/colitis">colitis</a>, or <a href="https://feedreal.com/glossary/pancreatitis">pancreatitis</a>. In that case, most veterinarians recommend a prescription diet claiming to be" highly digestible, great tasting, nutrition clinically proven to help settle digestive upsets."

One aspect of canine nutrition that all animal and veterinary nutritionists agree upon is that dogs have no requirement for <a href="https://feedreal.com/glossary/carbohydrates">carbohydrates</a>! Yet all of the veterinary nutritionists'" formulated prescription diets are loaded with excessive levels of carbohydrates.     Studies have shown that diets high in refined carbohydrates, such as corn or wheat, can lead to imbalances in the gut microbiota and contribute to inflammation and altered gut permeability. Other dietary factors that lead to gastrointestinal disorders in dogs include 

Diet Comparison Hill's Prescription Diet Gastrointestinal Biome Dry Dog Food 

INGREDIENTS: Chicken, Cracked Pearled Barley, <a href="https://feedreal.com/glossary/brewers-rice">Brewers Rice</a>, Corn <a href="https://feedreal.com/glossary/gluten">Gluten</a> Meal, Whole Grain Corn, Whole Grain Oats, Ground Pecan Shells, Chicken Liver Flavor, Chicken Fat, Powdered Cellulose, Flaxseed, Dried Beet Pulp, <a href="https://feedreal.com/glossary/pork-liver">Pork Liver</a> Flavor, Dried Citrus Pulp, Soybean Oil, Fish Oil, Calcium Carbonate, Dicalcium Phosphate, Lactic Acid, Potassium Chloride, <a href="https://feedreal.com/glossary/pumpkin">Pumpkin</a>, Pressed Cranberries, L-Lysine, Iodized Salt, Choline Chloride, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Thiamine Mononitrate, Niacin Supplement, Calcium Pantothenate, Vitamin A Supplement, Riboflavin Supplement, Pyridoxine Hydrochloride, Vitamin B12 Supplement, Biotin, Folic Acid, Vitamin D3 Supplement), Ginger, Psyllium Seed Husk, L-Threonine, Taurine, L-Tryptophan, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), Mixed Tocopherols for freshness, Natural Flavors, Beta-Carotene.

Fresh Whole-Food Diet for Gastrointestinal Disorders

A whole-food diet that supports gastrointestinal (GI) tract health in dogs focuses on providing easily digestible, nutrient-rich ingredients that promote optimal digestion, maintain a balanced gut microbiome, and reduce the risk of inflammation. A whole-food diet for GI tract health includes:

Despite the advice from most veterinarians, dogs with <a href="https://feedreal.com/glossary/chronic-kidney-disease">Chronic Kidney Disease</a> (CKD) should not be fed a reduced protein diet. Based on a faulty study performed on rats, veterinarians have been led to believe that too much protein damages the kidneys and that limiting protein intake delays the progression of renal disease. 

Additional studies using dogs instead of rats disproved this theory and showed that dogs fed lower protein levels had a higher mortality rate. An article published over 50 years ago revealed that switching dogs from dry dog food to a meat-based diet benefited the dogs ' kidneys by improving the glomerular filtration rate.

Another study revealed that dogs fed a reduced-protein diet failed to adjust renal tubular excretion of sodium and phosphate, leading to further kidney damage. 

Several pet food companies now sell low-protein prescription diets for dogs with chronic kidney disease, and dog owners who make their bowls at home are advised to avoid feeding their dogs red meat, poultry, and other high-protein meals. However, if a dog is fed a diet deficient in protein, the body will scavenge protein from the muscle tissue.

Diet Comparison Hill's Prescription Diet k/d with Chicken Dog Food 

INGREDIENTS: Brewers Rice, Chicken Fat, Brown Rice, Whole Grain Sorghum, Chicken, Dried Beet Pulp, Egg Product, Hydrolyzed Chicken Flavor, Corn Gluten Meal, Fish Oil, Pork Liver Flavor, Calcium Carbonate, Lactic Acid, Soybean Oil, L-Lysine, Potassium Chloride, Betaine, Whole Grain Oats, DL-Methionine, Fructooligosaccharides (FOS), vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Niacin Supplement, Thiamine Mononitrate, Calcium Pantothenate, Pyridoxine Hydrochloride, Vitamin A Supplement, Riboflavin Supplement, Biotin, Vitamin B12 Supplement, Folic Acid, Vitamin D3 Supplement), Potassium Citrate, Choline Chloride, L-Threonine, Iodized Salt, Taurine, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), L-Tryptophan, L-Carnitine, Magnesium Oxide, Mixed Tocopherols for freshness, Natural Flavors, Beta-Carotene.

The guaranteed analysis indicates that the food has 15.6% protein. Studies have demonstrated that dogs with reduced kidney mass (up to 75%) have increased renal function when fed 27% and 56% meat-based protein, while the dogs fed 19% protein do not have improved renal function. The study followed the dogs for four years! 

Rather than decreasing protein intake, you need to reduce phosphorus levels by lowering organ content and feeding lean meats. You should also limit sodium intake, as excessive sodium can contribute to fluid retention and worsen hypertension (high blood pressure) in dogs with CKD.

A fresh, whole-food diet for dogs with chronic kidney disease would contain the following:

Read <a href="https://feedreal.com/articles/what-to-feed-a-dog-with-kidney-disease">What To Feed a Dog With Kidney Disease</a> for a comprehensive guide to feeding a dog with kidney disease.

A <a href="https://feedreal.com/glossary/bladder-stone">bladder stone</a> is a hard mass that forms in the urinary bladder. It is typically composed of minerals and salts that have crystallized and accumulated over time. Bladder stones can vary in size, shape, and composition, and they can cause discomfort, pain, and various urinary clinical signs in affected animals.

The specific composition of the stone depends on several factors, such as the mineral content of the urine, pH levels, and other underlying conditions. Common bladder stones in dogs include struvite, calcium oxalate, calcium phosphate, urate, cystine, and silica stones.

Diet Comparison Hill's Prescription Diet u/d Dry Dog Food 

INGREDIENTS: Brewers Rice, Corn Starch, Whole Grain Corn, Chicken Fat, Egg Product, Flaxseed, Potato Protein, Chicken Liver Flavor, Lactic Acid, Calcium Carbonate, Potassium Citrate, Dicalcium Phosphate, L-Lysine, Iodized Salt, vitamins (Vitamin E Supplement, Niacin Supplement, Thiamine Mononitrate, Pyridoxine Hydrochloride, Calcium Pantothenate, Riboflavin Supplement, Biotin, Vitamin B12 Supplement, Vitamin A Supplement, Folic Acid, Vitamin D3 Supplement), Potassium Chloride, DL-Methionine, Choline Chloride, Taurine, Magnesium Oxide, minerals (Zinc Oxide, Ferrous Sulfate, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), L-Carnitine, Mixed Tocopherols for freshness, Natural Flavors, Beta-Carotene.

It is stated that the diet is designed to help dissolve urate and cystine stones and decrease the risk of recurrence.

Fresh, Whole-Food Diet for Urinary Bladder Stones

Whole-food diet recommendations to reduce urate and cystine stones include:

Reduction of urate stones: Raw-fed dogs prone to urate stones should be fed lean muscle meats with low purine levels, such as skinless, boneless chicken breast or thigh meat, or skinless, boneless <a href="https://feedreal.com/glossary/turkey-breast">turkey breast</a>. Whitefish such as cod, haddock, or sole are low in purines and can be an excellent addition to the diet. Egg whites can also be fed, but the yolks should be avoided due to the high level of purines.

Reduction of cystine stones: Raw-fed dogs should be fed muscle meats that are generally lower in methionine and cystine to prevent cystine accumulation in the urine. Meats with lower methionine and cystine levels include:

Encouraging your dog to drink more water can help flush out minerals and prevent the formation of bladder stones. Some dogs can be encouraged to drink more fluids by adding water or bone broth to their meals. 

Altering the pH of the urine will help dissolve existing stones and prevent future stones. Struvite and calcium phosphate stones form in alkaline urine, so foods that promote acidic urine should be fed. Promoting alkaline urine can also be a preventative method for calcium oxalate and cystine stones.

Canine obesity has reached epidemic proportions worldwide! In the past 15 years, the number of overweight or obese dogs has risen from 42% to 56%. The higher percentage increase is in the obese category. The buildup of excess <a href="https://feedreal.com/glossary/body-fat">body fat</a> is the cause of the extra weight. 

Many veterinarians will recommend the use of a weight-loss prescription diet. However, examining the list of ingredients and the guaranteed analysis reveals that the diets are very similar to the high-carbohydrate diets the dog has been consuming. One of the leading causes of canine obesity is the consumption of too many carbohydrates, the macronutrients that dogs do not require!

Diet Comparison Hill's Prescription Diet r/d Chicken Flavor Dry Dog Food 

INGREDIENTS: Whole Grain Corn, Corn Gluten Meal, Chicken <a href="https://feedreal.com/glossary/byproduct">By-Product</a> Meal, Powdered Cellulose, Soybean Meal, Soybean Mill Run, Chicken Liver Flavor, Dried Beet Pulp, Pork Liver Flavor, Soybean Oil, Lactic Acid, Caramel color, Flaxseed, Chicken Fat, L-Lysine, Calcium Carbonate, Potassium Chloride, Choline Chloride, Potassium Citrate, Iodized Salt, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Niacin Supplement, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Riboflavin Supplement, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Folic Acid, Vitamin D3 Supplement), DL-Methionine, minerals (Manganese Sulfate, Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Calcium Iodate, Sodium Selenite), Taurine, Mixed Tocopherols for freshness, Natural Flavors, L-Carnitine, Beta-Carotene.

A study revealed that 19% of dog parents fed their dogs a therapeutic or prescription diet from their veterinarian as a weight loss method. When those dog owners were asked to rate the level of success achieved from feeding the prescription weight-loss diet, the response was that 13%  of the prescription weight-loss diets were very effective and 14% were somewhat effective." So only 27% of the dogs fed a prescription diet for weight loss successfully lost weight.

Fresh, Whole-Food Diet for Weight Reduction

Transitioning to a species-appropriate diet has many benefits for overweight dogs. The dog parent knows the exact components of the diet and has total control of the ingredients. A raw or fresh food diet will consist of muscle meat for protein, raw meaty bones for calcium, phosphorus, and other vital nutrients, secreting organs, seafood, and fiber. The diet contains minimal carbohydrates and no fillers. 

A raw or fresh food diet for weight loss should consist of muscle meat for protein, raw meaty bones for calcium, phosphorus, and other vital nutrients, secreting organs, seafood, and fiber. The diet should contain minimal carbohydrates (vegetables for fiber only) and no fillers. 

Understanding the fat content associated with different types of meat will allow you to select the best meat for your dog's bowl. The muscle meats with the lowest fat content are quail, wild rabbit, turkey, emu, goat, camel, and kangaroo.

Meats containing moderate fat include ostrich, domesticated turkey, rabbit, venison, bison, and veal. And meats to avoid due to the high-fat content include duck, goose, lamb, pork, and beef.

Diet Comparison Hill's Prescription Diet ONC Care with Chicken Dry Dog Food 

INGREDIENTS: Chicken, Whole Grain Wheat, Corn Gluten Meal, Chicken Fat, Hydrolyzed Chicken Liver, Soybean Meal, Brown Rice, Cracked Pearled Barley, Egg Product, Chicken Liver Flavor, <a href="https://feedreal.com/glossary/coconut-oil">Coconut Oil</a>, Fish Oil, Ground Pecan Shells, Pork Liver Flavor, Lactic Acid, Calcium Carbonate, Potassium Citrate, Flaxseed, Dried Beet Pulp, Dried Citrus Pulp, Carrots, Iodized Salt, DL-Methionine, Pressed Cranberries, vitamins (Vitamin E Supplement, L-Ascorbyl-2-Polyphosphate (source of Vitamin C), Niacin Supplement, Thiamine Mononitrate, Calcium Pantothenate, Vitamin A Supplement, Riboflavin Supplement, Biotin, Pyridoxine Hydrochloride, Vitamin B12 Supplement, Folic Acid, Vitamin D3 Supplement), Choline Chloride, L-Tryptophan, Natural Flavors, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), Taurine, Mixed Tocopherols for freshness, L-Carnitine, Beta-Carotene.

Although this product has a higher protein content, at 30.8%, it still contains 34.6% carbohydrates. It is still <a href="https://feedreal.com/glossary/kibble">kibble</a>&nbsp;created with several processing steps, including mixing, <a href="https://feedreal.com/glossary/extrusion">extrusion</a>, drying, and coating, at high heat, up to  300 to 400 ℉ (149 to 204 ℃) in some steps.

Temperatures over 160 ℉ cause fat oxidation and the formation of HCAs, AGEs, acrylamide, trans fats, and PAHs. When all these compounds are combined, a product loaded with harmful chemicals linked to cancer is created!

High-temperature processing is a double whammy, as it also decreases the natural antioxidants in the food. Antioxidants are substances that aid in protecting your dog's body from <a href="https://feedreal.com/glossary/free-radicals">free radicals</a>. Processed dog food, such as kibble, may induce oxidative stress in dogs, resulting in an imbalance of free radicals and antioxidants in their bodies, increasing their risk of cancer.

Fresh, Whole-Food Diets for Cancer Patient Support

A fresh, whole-food diet to support dogs with cancer comprises the following:

Comparison of a Prescription Diet to the Equivalent Standard Diet

A prescription diet's ingredients do not vary significantly from standard diets. When making a side-by-side comparison of the Hill's Prescription Diet Gastrointestinal Biome Dry Dog Food to the Hill's Science Diet Adult Perfect Digestion Chicken, Barley &amp; Whole Oats Recipe Dog Food, the prescription diet has only six additional ingredients: L-lysine, ginger, psyllium seed husk, L-threonine, taurine, and L-tryptophan. 

Four additional ingredients, L-lysine, L-threonine, taurine, and  L-tryptophan, are amino acids that should not be needed if high-quality complete proteins are used in the food. 

Psyllium seed husk is a soluble fiber that absorbs water and forms a gel-like substance in the digestive tract. It is commonly used in weight management diets to create a sense of fullness. It is added to aid your dog's digestive tract by bulking up the stools and alleviating diarrhea.&nbsp;

Ginger has been traditionally used to support digestion and alleviate gastrointestinal discomfort. It is the only therapeutic ingredient in the whole-food diet and is recommended.

We used this example of a standard diet compared to a prescription diet to demonstrate that there is very little difference in ingredients, yet the difference in cost is significant. Hill's Prescription Diet Gastrointestinal Biome Dry Dog Food averages $4.66 per pound, while the Hill's Science Diet Adult Perfect Digestion Chicken, Barley &amp; Whole Oats Recipe Dog Food averages $3.78 per pound. That equals a 21% difference in price between the two diets. These are the prices per pound if you purchase the large bags, over 22 pounds. 

Hill's Prescription Diets are not the only therapeutic diets available. We chose to highlight their diets because they created the original prescription diets in 1948 when they released the" Canine k/d (for kidney diet). They continued from there, adding prescription diets for many common dog ailments. 

Two other big names in therapeutic diets emerged: Royal Canin® Veterinary Diet and Purina® Pro Plan® Veterinary Diets. Due to copyright laws, Hills can only use the term prescription diet. Therapeutic diets have a meager share of the total dog food market, less than 1%. However, the therapeutic diet market is projected to increase by 5.6% over the next five years. 

The two common myths about prescription diets are that they contain medication and that you must obtain a prescription to purchase them legally. Prescription dog food is not the same as medications. While they are formulated to address specific health conditions, they are not drugs. They are specialized diets that claim to support specific health issues through nutrition.

While veterinarians often recommend prescription diets, not all brands or retailers require a written prescription for purchase. The FDA does not regulate therapeutic diets, as the ingredients are considered nutraceuticals rather than pharmaceuticals. 

We have provided a glance at the prescription diet market. Many other diet types can be countered with fresh food diets. If your veterinarian is recommending a prescription diet, take the time to research the therapeutic ingredients in the diet. Compare the diet to its standard counterpart. Determine if the diet is genuinely therapeutic or if better whole-food options are available. 

What are Prescription Diets for Dogs?

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