Prescription diets for pets: lifesaver or scam?
A puppy with a veterinarian might be prescribed prescription diets for various ailments
Are prescription diets really good for dogs?

Suppose you've ever had a puppy with an upset tummy. In that case, you probably rushed to the vet and left with a hefty bill and a few cans of Hill's Prescription diets i/d Canine. Likewise, if you've had a cat with kidney problems, you may have walked away with the Prescription Diet k/d feline.

But why do some pet foods have prescriptions? Does your dog or cat need a veterinary prescription or therapeutic diet? Most importantly, is pet prescription food even food for dogs and cats? Let's start answering these questions by looking at what pet prescription or therapeutic food is.

What is a prescription, therapeutic, or veterinary diet for pets?

an apple with a prescription. Should food be prescribed?
Should food be prescribed for pets?

The rules on therapeutic or prescription diets remain unclear. There are four leading producers of prescription diets: Hill's, Royal Canin, Purina, and Wysong. Each of the four has specific product lines claiming to help with chronic illnesses.

  1. Hill's has the patented prescription diet plan marketed as being more specialized than their well-known science plan range. Their prescription diets claim to address particular illnesses and their dietary needs.
  2. Royal Canin Vet also claims to be formulated to meet the needs of specific ailments.
  3. Purina has the Pro Plan Health Food line, as well as a range of prescription foods.
  4. Wysong is a boutique pet food. They claim to be vet-formulated to help pets with chronic illnesses or those recovering from surgery.

Hill's has taken the lead in the industry by patenting the term "prescription diet," leaving the rest to call themselves veterinary or therapeutic diets.

In general, companies market these diets as being able to treat certain diseases in our pets. However, there are few, if any, independent clinical studies that support this. Nevertheless, vets prescribe prescription and therapeutic diets as though they are medicine.

Types of prescription diets for pets

There is a wide range of prescription or therapeutic pet foods that claim to treat specific health problems. These include:

  • Renal and kidney problems
  • Digestion issues
  • Diabetes
  • Allergies
  • Cancer
  • Skin and coat problems
  • Arthritis and joint issues
  • Obesity
  • Post-surgery recuperation
  • Dental disease
  • Heart problems

There is no doubt that many of these diets can be more helpful than the standard run-of-the-mill dry food found in a supermarket. But with their hefty price tag, are they essential? Or are they really a marketing gimmick?

Pet prescription diet lawsuits

a cat eating food from a veterinarian

Before we delve deeper into prescription diets, we need to first look at the legal aspects.

Hill's has been embroiled in more than one scandal.

In 2007, their prescription cat food m/d tested positive for high levels of rat poison. This came around the same time as massive food recalls for melamine contamination. It should also be mentioned that corn and low-grade cereal by-products that make up so much of the prescription foods are also the primary cause of mycotoxins in dog food, a common cause of disease.

Currently, there is also an ongoing class-action lawsuit against manufacturers and retailers of prescription diets. The lawsuit was originally dismissed in 2017. However, the California Appeals court ruled the dismissal was an error.

The California Appeals court ruled that the practice of selling food solely through vets or with prescriptions was misleading. They also stated that the key companies with a monopoly on therapeutic and prescription foods, Mars Petcare, Purina, and Hill’s, disregarded the FDA’s compliance policy guidelines on pet food. Meanwhile, the FDA did nothing to intervene.

The lawsuit argues that there is no legal mandate for these foods to be prescribed. It also points out that there is no significant difference between prescription pet food and other brands—other than price.

Companies also make medical promises as part of their branding. To be clear, the FDA itself clearly states that it does not authorize or require a prescription for any pet food. Nevertheless, retailers require a prescription for this food. Even products purchased on Amazon—where they are available—require that you submit your veterinary information at check-out.

Examples of medical claims on packaging or labels

  • Purina Pro Plan Veterinary Diets UR Urinary Ox/St Canine Formula claims to help reduce the risk of urinary stones.
  • Hill's Prescription Diet™ k/d™ Feline claims to be clinically proven to support a longer and healthier life for cats with kidney problems.
  • Royal Canin Hepatic Loaf Canned Dog Food "is formulated to support liver function."

These are specific health claims that manufacturers should back up with peer-reviewed, independent trials. Still, the FDA essentially leaves the efficacy of these diets up to the companies themselves.

So, these diets are treated as medical drugs. Yet, they do not actually have any medications in them.

Another point the lawsuit makes is that the Mars company that owns Royal Canin also owns BluePearl Vet Hospital and has a majority share of Banfield Pet Hospital. Both of these major veterinary chains are retailers of these prescription diets. It seems clear that this is a conflict of interest.

This isn't the only lawsuit Hill's is involved in. Recently, they settled for $12.5 million to customers who bought Hill's Prescription Diet or Science Diet canned dog food. This is because between Sept. 1, 2018, and May 31, 2019, these products contained dangerously high vitamin D levels.

The cost of prescription, veterinary, and therapeutic foods

Blueberries in Rx bottle. Should prescription diets be allowed if its just normal food with no medicine?
Should prescription diets be allowed if there is no medicine in it?

Another key problem with prescription pet foods is their cost.

Most “premium” dog foods cost about $0.41 per pound to the manufacturer, and after distribution and retailer costs, the average price goes up between $1 and $2 a pound.

Below, we will look at the exact ingredients of two major prescription foods, but first, let's look at what these foods go for.

By using Pet Assistant’s Food Finder to compare the price and nutrition of prescription, veterinary, therapeutic pet foods, we can get an idea of the average price range for these diets.

Hill's Prescription Diet l/d Liver Care Pork Flavor Dry Dog Food has an overall nutrition score of 7% (out of 100), a daily price of $2.86 and a monthly cost of $86.

This is still extremely cheap compared to a 15lbs can of Hill’s i/d Digestive Care Chicken & Vegetable stew canned dog food. This has a nutrition score of 20% and costs an eye-watering $46.69 dollars a day. That makes $1409 per month!

The image below shows the Food Finder comparison for a slightly cheaper but similar product.

By comparison, we can see that a more nutrient-rich, fresh diet can be obtained from Rigo’s. One of their meals goes for just $5.95 a day, or about $180 a month, which has an 80% better nutritional profile.

In fact, for a daily $0.68 you can feed your dog freeze-dried Instinct, which would still have a slightly better nutritional profile than the canned prescription diet.

A similar pattern exists in the other main culprits of veterinary and therapeutic diets. Cans of Purina Pro Plan Veterinary Diets average around $7 to $15 a day, with a nutritional profile usually between 15 and 20%—worse than Hills.

Their dry food is slightly cheaper than Hills, but still above the norm for “premium” dog food. Keep in mind, AAFCO has no special requirements for a food to be labeled premium either.

a Jack Russell waiting for a bowl of dry dog food

Mars Petcare, which is responsible for Royal Canin Veterinary Diets, has nutritional profiles ranging from 21 to 26 %. A can will cost you between $11 and $19 a day.

For the same cost ($11,95), you can get food with a complete nutritional profile from Rigo’s, or try Blackwood’s specialized formulas that have a similar nutritional score and are only $0.95 a day.

Does my dog or cat really need a prescription diet?

Tellingly, many of these products can be bought on Amazon, Chewy, and Petco. None of these are licensed pharmacists. Therefore, it's unnecessary retailers still require a veterinarian to prescribe them, especially since the FDA does not require it.

In fact, when we go through the ingredient list of some of these foods, we see that there are no unique ingredients in them either that make them much better than most other mid-range quality dog foods.

We can concede that a diet with less copper can help support liver function, as in the Hepatic Loaf dog food. And a lower protein diet can help support kidneys. The problem is that you can find a great variety of diets with less copper or lower protein. They do not need to be prescribed.


What is actually in prescription diets?

It's beyond the scope of this article to look at all the ingredients of all the veterinary, therapeutic, or prescription diets on the market. But let's look at the components of one of the most popular diets: Hill's Prescription Diet i/d Canine.

As with any pet food, the first ten ingredients are the most important. But we will look at everything up to the salt divider. This is because everything after the salt has to be less than 1% of the total mass in the pet food industry. So these will mostly be the minerals and vitamins that companies put back into the food after the rendering and extrusion process originally destroyed them.

The ingredients in this prescription food are:

  • Brewers rice
  • Corn
  • Chicken meal
  • Pea protein
  • Egg product
  • Pork fat
  • Corn gluten meal
  • Chicken liver flavor
  • Dried beet pulp
  • Lactic acid
  • Pork liver acid
  • Soybean oil
  • Potassium Chloride
  • Iodized salt

There are more ingredients listed after the salt, but we will discuss these later.

Interestingly, brewer's rice is the first ingredient in this diet since this means there is more of it than other ingredients in the food. Brewer's rice is a cereal by-product, or the tiny bits manufacturers have left over after rice has been milled. It is low in nutrients but reasonably high in calories.

The second ingredient is corn. But also note that the seventh ingredient is corn gluten meal. Why are corn products mentioned twice? This is an example of ingredient splitting. A company can split corn into two separate ingredients rather than one large one. This allows for other ingredients to move higher up the list as it makes the corn content look less than it really is.

Like brewer's rice, corn does not have much nutritional value, although it is high in calories. The meal is a red flag as it can cause spikes in blood glucose due to being overly processed. This is not great for dogs with pancreas problems or who are prone to diabetes.

Corn is also a cheap way to up the protein content of the food, even if it doesn't really do much in terms of nutrients.

The third ingredient is chicken meal. Chicken meal is all the parts of the chicken not fit for human consumption, cooked, dried out, and ground into a powder.

Chicken meal is technically a more abundant source of protein than raw chicken. Still, no meal product is as good as the original food it was made from.

The process of cooking or rendering the chicken alone denatures the protein. This is why companies put the amino acids back into the food after it's made. This is why you will see additions such as taurine, L-tryptophan, and Thiamine. The original rendering and extrusion process destroyed these vital protein building blocks. So the manufacturer replaced them after processing.

The fourth ingredient, pea protein, is potentially problematic. Like corn, pea flour can be a cheap way to increase protein content without using expensive animal proteins. In fact, companies commonly used it in grain-free diets. However, legume protein doesn't have a great amino acid profile to suit a dog's need and it has been linked to the rise in heart disease in dogs on grain-free diets.

The fifth ingredient, egg product, seems harmless on the surface. In general, eggs are a great source of vitamin Bs for dogs. Although we can see by the list of vitamins replaced in the food, they probably didn't make it through the extrusion process. Furthermore, egg product is never fit for human consumption.

It may be any waste from eggs that failed to hatch, didn't make the grade for human consumption, or egg liquid leftover from breaking.

Everything after these first five ingredients is likely in such small quantities, it isn't really worth discussing. Although, we will mention the presence of pork fat and chicken liver flavor.

Manufacturers often add these to the dry pellets as palatants to dupe your dog into eating it. Pork fat is a by-product of the rendering process. Pet foods plants scoop it off the top of the vats while the meat is being cooked, and, yes, it's a pretty low-quality ingredient.

The other palatant, chicken liver flavor, is unlikely to have much to do with chicken liver. Instead, it is more probably a type of chemical flavoring that smells good to dogs.

To sum up, there is nothing in this ingredient list that is nutritious for dogs. There is undoubtedly no medicine in it. You can’t find anything in it that isn’t present in another cheaper dog that doesn't consist mainly of processed corn.

What's more, you can find foods that have near identical ingredients at a fraction of the cost. These prescription diets can be as much as eight times the price of food with the same ingredients! Using the Pet Assistant Food Finder Tool can help you find healthier foods, with the same or better benefits, for lower prices.

The same applies to other prescription diets. Hill’s conducted a clinical study that reports that dogs with joint problems who are given the j/d prescription diet can be given less non-steroidal anti-inflammatory drugs. But the report is clear that the reason for this is the high levels of omega-3 fatty acids and EPA.

This is not revolutionary, nor is it irreplaceable. The food comparison tool from Pet Assistant can help you find a far more budget-friendly diet for your dog with equal amounts of omega-s and EPA. At Pet Assistant, you will soon be able to compare ingredients and find foods with nearly identical ingredients and varying prices.

Are are therapeutic or prescription diets for cats necessary?

The ingredients in Hill's Prescription Diet for Cats raise even more eyebrows. The diet for kidney care lists the following components:

"With Chicken: Brewers' rice, animal fat, maize gluten meal, chicken (18%) and turkey meal, pea protein, wheat, dried whole egg, minerals, digest, dried beet pulp, rice protein concentrate, fish oil, soybean oil, L-carnitine, vitamins, taurine, trace elements, and beta-carotene. With a natural antioxidant (mixed tocopherols)."

Firstly, while dogs are carnivores with the ability to digest certain plants, cats are true carnivores. So it's disconcerting that the label lists the first ingredient as "with Chicken," rather than just chicken.

According to the FDA, protein sources that stipulate "withe th", such as "with salmon," only need to have 3% of that ingredient in the food.

Adding the word "with" makes all the difference. If the label only said chicken, then 70% of the product would have had to be chicken, accounting for water added during processing.

So chicken as the first ingredient is misleading. After that, most of the ingredients look pretty similar to the canine digestive diet. Various plant and cereal by-products make up the bulk of the food and protein.

Note that the animal protein mentioned is chicken (18%) and turkey meal. This can be misleading since it is not clear whether 18% of all the food is chicken or just 18% of the meal ingredient.

Nevertheless, the presence of taurine implies that there isn't enough meat in the food to supply taurine naturally to the cat, so it has to be fortified.

A diet lower in protein for cats with kidney problems may be necessary since animal proteins can be hard for kidneys to break down. Similarly, lower amounts of phosphorus, sodium and higher omega-3s can really help cats with kidney diseases.

Although again, Pet Assistant’s Food Finder can help you find a cheaper option that aids kidney function and has more nutritional value for your cat.

Lastly, we treat and dry food for kidney problems with skepticism. By digesting food with very little water content, cats need to draw moisture from the kidneys. This constant state of dehydration is no good for renal issues.

Alternatives to a prescription diet for my pet

In general, whole, unprocessed foods will always be better than highly processed foods. While specialized diets are necessary, they can be better obtained using fresh, human-grade products that are species-appropriate.

We can find plenty of foods with identical ingredients but without the exorbitant costs.

For instance, Pet Assistant's nutritionists can help you put together a high fiber, low-glycemic index diet for a pet with diabetes and our Food FInder can help you find equivalent foods. So, pets prone to urinary stones can also be placed on a low protein, nucleic acids, calcium, phosphorus, sodium diets without prescriptions or unnecessary costs.

We can do the same for other ailments, including heart disease, liver, and digestive problems. Better diets can be created that are still high in nutrients and lower in calories to help your pet achieve optimal health.

Final thoughts

Prescription pet foods are essentially misleading and price gouging. Although they are marketed as medicine and need veterinary approval to be fed to your pet, there is nothing in them that cannot be found in other, better diets that need no medical approval whatsoever.

Like many aspects of the pet food industry, veterinary therapeutic diets are entirely a marketing gimmick. One glance at the ingredient list can confirm this. Nevertheless, Pet Assistant Food Finder can still construct alternative diets to suit a pet's specific ailment for a fraction of the cost.

NutritionPet healthPet nutritionPrescription diets