Prey Model Raw (PMR) diets for dogs & Cats

PMR diets are ratio based diets consisting of 80% muscle meat, 10% bone, 5% liver, and 5% other secreting organ. Many join Raw Fed & Nerdy because they hear that PMR diets are not “complete” or “balanced.” Many dogs appear to do quite well on PMR diets. Others often face issues with constipation (lack of fiber or bone content), loose stools (poor transitioning, too much fat), unwanted changes to weight (incorrect kcal density), and many other obstacles.

First and foremost, PMR diets can certainly be made to be nutritionally optimal for many dogs and cats. Many owners choose to use PMR diets as a base to work off of. However, PMR diets alone are never nutritionally optimal for adults and are often dangerous for growth diets. Growth diets are more complex, so for the sake of the rest of the material, we are discussing adult diets. However, much will still apply to growth diets.

The goal of this piece is to not cause panic or lead the owner to believe that every day’s feeding must be perfect, but rather discuss how PMR diets alone are not optimal for pets as a long-term solution. Nutrition is a learning process and we are more than happy to help at Raw Fed & Nerdy.

As a side note, a common response to content like this might be “wolves don’t have calculators.” However this is erroneous reasoning and those statements are addressed in our free full course in the introductory units.

Absence of Essential Nutrients in PMR Diets

There is more to a quality whole food diet than nutrients, but it is still critical that the basics (essential nutrients) are covered. Generally speaking, PMR only diets will be low in vitamin D, vitamin E, Iodine, Manganese, and Omega 3. PMR diets are sometimes low in zinc, copper, and thiamin. Let’s examine whole food sources of these nutrients which will provide insight as to why these are often low or absent entirely. Keep in mind that checking off these ingredients does not replace a diet check. For example, feeding eggs and atlantic mackerel a couple times a week does not ensure enough vitamin D is being fed.

Vitamin D

You won’t typically find vitamin D in meaningful amounts in bones, organs, or “muscle meat.” While liver provides some vitamin D, it is not nearly enough- especially because vitamin D should be at a level that compliments the often higher amounts of vitamin A in a PMR diet. Pork, when not factory farmed, can also provide decent amounts of vitamin D, but its use is rarer in PMR diets. Vitamin D can be provided in appreciable amounts from oily fish. Eggs can often “round out” the amounts needed in the diet, but eggs alone should not be relied upon.

For reference, a 65 lb dog will require about 6 mcg of vitamin D per day. Get your pet’s nutrient requirements here.

Vitamin E

Vitamin E will be extremely low in a PMR only diet. Vitamin E status can be made worse when the muscle meats selected are higher in unsaturated fat (compared to saturated fat) as polyunsaturated fatty acids increase the requirement for vitamin E. Examples of foods high in polyunsaturated fat also include fish, fish body oils, and brain. Highly active dogs will also have an increased requirement for antioxidants- including vitamin E. Plant matter will often contain whole food sources of vitamin E, but providing enough can be difficult. Some dogs do well with quite a bit of plant matter while others do better with very little. The Raw Fed & Nerdy formulation sheet will automatically calculate the updated vitamin E requirement by tallying up the amount of polyunsaturated fat in the recipe. However, most people tend to dose vitamin E (as d-alpha tocopherol NOT dl-alpha tocopherol) daily using the following chart. If you can find a brand with mixed tocopherols (such as Solgar) that is preferred over a brand with only d-alpha tocopherol. You can still include food based sources.

Manganese

Manganese can be found in digestible, cooked plant matter which often does not make an appearance in PMR diets. There are great animal based sources of manganese as well. Raw green tripe is a rich source of manganese. However, many tripe products will be very high fat so they may not be a good choice for every diet. Blue mussels (not green) are extremely rich in manganese. Finally, some joint supplements will already contain appreciable amounts of manganese, so be sure to check the label if you are feeding one. Unfortunately, GLM powder, while a great addition, does not provide significant amounts of manganese. Although some like to suggest fur and feather as potential sources of manganese for dogs, such sources are not digestible and large quantities would need to be fed. Ginger is another food that is suggested. However, it is a hot and drying herb and it does not contain as much manganese as other common food sources, so the amount required to meet the requirement can result in the diet being too spicy, and at the same time, possibly causing digestive side effects

For reference, a 65 lb dog will require about 2 mg of Manganese per day However, the recommended allowance for dogs is extrapolated and experimentation may be needed to know what dose your pet does best at. Get your pet’s nutrient requirements here.

Iodine

Iodine is found in foods closer to the sea. However, meat products in general will have trace amounts of iodine. A diet with seafood will have more iodine than a diet without, generally speaking. Iodine can be found in iodized salt, but it is extremely rare that an adult dog or cat diet will need additional sodium chloride. A better choice for iodine, generally speaking, would be kelp. Keep in mind that many kelp products will not provide the amount of iodine present in the product. Most often, this leads to too much iodine being fed. NOW tests each batch of kelp and provides the iodine amount on the label of each bottle. Regardless of the brand, make sure they provide you with the iodine amount before purchase.

For reference, a 65 lb dog will require about 325 mcg of Iodine per day However, adult dogs can adjust to varying levels of iodine in their food. We don’t typically recommend meeting the RA for iodine since natural amounts are provided in meat that are not reflected in nutrient analysis’.  Get your pet’s nutrient requirements here.

Omega 3

Omega 3 is an essential fatty acid and is not found in significant amounts in muscle meat, organs, and bones. There are many different forms and sources of Omega 3. Generally speaking, Omega 3 as EPA and DHA is the most bioavailable. Omega 3 is easy to provide through a fish body oil or through whole, oily fish. Whole oily fish will provide vitamin D (and other essentials), which can be useful. However, pets who are limited in calorie intake may be better off with a high quality fish body oil product (such as Nordic Naturals Omega 3 Pet). For pets who cannot have fish, brain is a fantastic source of preformed omega 3. 

For reference, a 65 lb dog will require about 0.38 g of EPA + DHA per day. Get your pet’s nutrient requirements here.

Zinc

Without a proper diet assessment, it can be difficult to assess how much zinc is being provided and whether that is enough. Zinc can be found in lean red meats. Owners who are feeding higher fat cuts of red meat to a pet with lower energy requirements will certainly not meet the zinc requirement. Furthermore, northern breeds and many health conditions mean that the dog will need even more zinc than what is originally calculated. Eastern oysters provide a lot of zinc! However, they also provide quite a bit of copper. A dog eating 5% liver from ruminant sources (ex: beef) may not do well with the extra copper. Zinc is often one that is supplemented. Because it is a mineral and too much can harm copper status, we won’t be making supplement recommendations here as a diet analysis is recommended before adding any supplements.

For reference, a 65 lb dog will require about 26 mg of Zinc per day. Get your pet’s nutrient requirements here.

Copper*

Copper tends to only fall short in PMR diets when the liver source is consistently poultry or pork based. Even at 5%, there will not be nearly enough copper when using chicken liver, for example. Pork liver also contains copper on paper, but the form has very low bioavailability. Diets that utilize primarily ruminant sources of liver- such as beef or lamb- will be providing more than enough copper. If using poultry liver, you do not want to increase the amount fed just to provide copper. You will quickly find that it drives the vitamin A too high. Of course, you can boost Copper in the diet by providing eastern oysters (which also has zinc) or by adding in poultry hearts. That being said, if you are only able to feed poultry or pork liver, a diet analysis is strongly encouraged to see if your other ingredients are rounding out the copper requirement.

For reference, a 65 lb dog will require about 3 mg of Copper per day. Get your pet’s nutrient requirements here.

Thiamin*

Thiamin, AKA vitamin B1, can sometimes fall short in a PMR diet. The risks may be somewhat mitigated compared to a kibble diet because PMR diets are not high carb (which can affect the thiamin requirement). However, the RA should certainly be met for thiamin regardless. Thiamin is found in meat, but unless pork or duck meat (not the skin which adds significant fat) is used regularly, thiamin often falls short. However, a full diet analysis will tell you if you are providing enough Thiamin. Pork and duck free diets can have enough Thiamin, it is just a bit more difficult to do at chance.

For reference, a 65 lb dog will require about 1 mg of Thiamin per day. Get your pet’s nutrient requirements here.

Iron*

While we might be able to meet dog’s iron requirement with the basic PMR, cat’s high iron requirement requires a staple presence of a specific organ, the spleen. Rotation, ironically, can make it harder to meet cat’s iron requirement.

Dogs who eat a diet lacking in red meat can also miss out on iron. Spleen is a very simple and straight-forward way to add iron.

For reference, a 11lb dog will require 3.34mg of iron, while a cat eating 250kcal will require 5mg of iron per day. Get your pet’s nutrient requirements here.

Balance Over Time?

Many say that PMR is about wide variety and balancing over time. However, balance over time still requires planning and not everything is easily balanced over time. While one can feed 5+ different protein sources (say rabbit, beef, chicken, turkey, venison), none of those items will cover the at risk nutrients outlined above.

Take for example vitamin D. Vitamin D is a fat soluble vitamin and can be stored- a prime candidate for a nutrient that can be balanced over time. However, you still have to know how much to feed. If you feed vitamin D once a week covering 2-3 days worth of vitamin D needs, you still aren’t providing the weekly requirement (the daily requirement multiplied by 7). Furthermore, fat soluble vitamins are found in foods with fat. Feeding higher fat meals is not an option for many dogs.

Water soluble vitamins (generally speaking) are not stored like fat soluble vitamins. The body does have the ability to “recycle” nutrients, but this requires resources. For this reason, water soluble vitamins, such as thiamin, are best provided daily when possible. Given the body’s mechanisms to recycle and reuse nutrients, it does not mean that cheat meals are going to result in a deficiency.

We could touch on every essential nutrient and decide whether it can or can’t be balanced over time. This process still requires the use of nutrient requirements and formulation. If a diet consistently does not provide elusive nutrients, like manganese, we cannot expect a balance over time approach to cover the manganese requirements.

Also keep in mind that adult pets can modulate how much of each nutrient they absorb in the diet, however, there are still limits to how much the pet can absorb at a time. 

Good storage capabilities

Energy & Nutrient Density of PMR Diets

Perhaps one of the biggest issues with PMR diets that are not audited (or any diet really!), is that energy and nutrient density is not addressed. Take for instance this common scenario: An owner decides to move their adult dog to a raw diet. The owner was previously feeding kibble, which is often less expensive than a raw diet. Being able to feed pets a whole food diet is a luxury and difficult for many owners. The owner may select higher fat ingredients to save money. The owner selects 80/20 ground beef, chicken liver, beef spleen, and chicken wings. They are also able to add some great additions like atlantic mackerel and eggs. However, the dog begins to put on weight because the diet is high fat and the dog is not requiring as many calories. The common advice is to decrease the overall amount of food fed- say from 2.5% to 2%. While this does decrease calories fed, it also decreases the nutrients. Instead, lower fat foods should be provided. This isn’t suggesting to feed a low fat diet, but rather decrease fat as fat is the chief energy component of the diet and displaces many micronutrients found in the lean portion of the diet. By decreasing the diet without auditing it, the amino acids, microminerals, and water soluble vitamins have been decreased.

As a side note, this is not unique to PMR diets. Many owners feed premade raw or kibble outside of the recommended feeding guidelines provided by the maker of the food. They may be shorting their pet the essentials. This would include taurine precursors and taurine itself. A shortage is detrimental to the heart.