Protein is arguably the most important part of your pet’s diet. In today’s dog food market, there are so many protein sources to choose from. But what is the best type of protein for your dog’s best health? Is there such a thing as too much protein? Is it better to feed your dog a variety of protein sources, or to stick with just one, single protein source? What's the difference between plant proteins and meat proteins? Is a vegetarian diet good for dogs?
In this article, we discuss the different kinds of protein available for dogs, and rank them according to their nutritional value. Since 30-70% of your dog’s diet is going to be protein, it may as well come from a healthy, quality source. We’ll help you make the right decision when it comes to the right kind of protein for your dog’s individual needs.
Essential Amino Acids
Put simply, amino acids are the building blocks of protein. There are twenty-two amino acids: ten of which are essential to dogs. Essential means that the body is unable to produce it (or at least not enough of it to support normal function), so it must be acquired through diet or supplements.
Essential Amino Acids for Dogs:
Some essential amino acids get more recognition than others, but all are required to keep your pet healthy. You can think of amino acids as a chain, so when one of them is missing, the others cannot perform properly. Scientifically, these are known as limiting amino acids.
What role do amino acids play?
Amino acids work together, but each plays a different role in the body. Histidine, for example, is an essential amino acid that the body uses to make histamine. Histamine is part of an immune response to protect the body from foreign pathogens like allergens and bacteria. Without it, the body has no first line of defense, leaving your pet susceptible to many illnesses and infections. Histidine also helps make Hemoglobin, which carries oxygen through the bloodstream.
Another commonly known amino acid is Lysine, which is necessary for collagen production. Collagen is the basic makeup of tendons, ligaments, and cartilage. It is also necessary for healthy skin, hair, and nails. Lysine encourages the production of carnitine, which regulates the metabolism and helps the body burn off fatty deposits and build muscle mass.
The rest of the essential amino acids assist in maintaining all functions of the body from healing minor skin abrasions to regulating systems like digestive health, cognitive function, and hormone release.
Dietary Sources of Essential Amino Acids
Dietary sources of essential amino acids are found within proteins, with the highest concentrations generally found in animal protein and lower concentrations in vegetable, legume, and grain proteins. Also, meats and animal-sourced proteins (eggs) have full amino acid profiles in favourable ratios. This means that they contain all essential amino acids in proper concentrations, while most vegetarian sources need to be combined in order to provide the full spectrum of essential amino acids. This is why it’s so important to feed a high quality pet food to your pet.
Lower quality foods high in fillers like corn, wheat, or soy contain fewer amino acids, especially if they are heavily processed. Milling grain removes amino acids, as many of them are found within the skin or hull.
Low quality pet foods contain animal protein, but the processing and nature of the meat affects the amino acid and nutrient content. By-products or rendered meats (listed as chicken meal or other meals) will not contain sufficient levels of essential amino acids. Higher quality foods include higher concentrations of animal proteins rich in amino acids.
Proteins are made up of different amino acids, which are necessary in different quantities for your pet’s total system functioning and muscle development and maintenance. Whatever protein is unused will be broken down and stored as fat or used as energy, depending on your dog’s calorie intake. Proteins cannot be stored as protein in the body and unused amino acids will be excreted in the urine.
When your pet is on a high-protein diet, it’s essential that they are hydrated, as protein metabolism requires plenty of water. Supplementing high-water fruits and veggies, feeding canned food (solely or alternating with dry food), and encouraging drinking can help ensure your dog does not become dehydrated.
When it comes to the amount of protein that is in your pet’s food, it’s not just the protein percentages that you have to worry about. Protein percentages on your dog food label give you an idea of how much crude protein is in your pet’s food. What they don’t tell you is that these levels are not indicative of how much of the food’s protein your dog is able to digest and use. So, while your dog food may have 25% crude protein, some of this protein will not be usable by your pet. A particular protein’s digestibility is referred to as its bioavailability or its biological value.
Some foods are more naturally bioavailable to dogs, such as animal-based proteins, but bioavailability also changes with how a food is cooked. Cooking at extreme temperatures can decrease the amount of protein your pet is able to use.
Raw, freeze-dried, dehydrated, or frozen foods retain the most bioavailability, followed by slow-baked foods, and then by high-temperature processing, such as the extrusion process that most dry kibble undergoes. The extrusion process affects the amino acid structures, which causes heat-sensitive amino acid chains to reform, bond with carbohydrates, and become less usable or unusable for certain important body functions. This is called a Maillard Reaction, and it decreases the ability of tissue to use amino acids effectively. Though the same protein source, the food has less biological value, or is less bioavailable.
Fresh Meats Versus Meat Meals And the Alternatives
Everyone knows to look for fresh meats in your pet’s food. But this advice in itself can be misleading, as only around 35% of a kibble’s weight can be fresh meats (including water weight) for a smooth manufacturing process (extra water gums up the machinery). This could make the overall protein-from-meat ratio on dry dog foods pretty low if a pet food only contained fresh meats.
However, meat meals are rendered, which means they are cooked at extreme temperatures. As stated before, this decreases the biological value of the meats in question. While they are denser in protein than fresh meats, meat meals are not as high quality protein.
There is an alternative that you can find in some high-quality pet foods today. Dehydrated or freeze-dried ingredients are now added to some high-quality kibble diets after kibble extrusion to enhance the bioavailability of the food. Their minimal heat processing makes them healthier than meat meals and fresh (only before processing) ingredient inclusion.
Primary Protein Sources
All dog foods, even limited ingredient or single protein diets, contain multiple sources of protein. Since proteins can be found in vegetables, grains, seeds, and legumes, as well as meats, your pet food’s actual protein makeup is a combination of several protein sources.
Determining your dog food’s primary source(s) of protein can help you assess the food’s quality. While nutrition is more complex than a few quick rules or tips, this can give you a pretty good idea of how your dog food's protein ranks. The simplest way to find your dog food's primary source of protein is to look at the first 6 ingredients in your pet’s food. If your pet is on a limited ingredient or single protein diet, limit your assessment to the top 3 ingredients in your dog’s food for a more accurate result.
Ingredient Splitting occurs when many ingredients that are very similar are separated in the ingredient list, making it appear that there is less of that ingredient in the food. If this happens early on, such as with this example below, it can make the difference between whether a grain or a meat is the primary protein source in your pet's food. It can be an important factor when it comes to assessing your pet food's primary protein source.
Notice that the first two ingredients are chicken meal and chicken - two high quality proteins. However, he next 4 highest in quantity by weight are oatmeal, dehulled barley, brown rice, and brewers rice - 3 similar grains (2 are the same grain). Barley, in particular has a high protein content, which could skew the meat protein versus grian protein ratio. Also, four grains in the top 6 ingredients means that the carbohydrate content of this food would likely be much higher than is optimal for dogs.
In the next dog food (Beneful), you can find an even worse example. The first ingredient is not even a meat, but ground yellow corn - a low-quality grain. Chicken by-product meal is the next ingredient, followed by more corn! Corn gluten meal is actually the protein-heavy portion of corn, which would push the corn-based protein content even higher.
Be ingredient savvy - if you see too many similar grain or carbohydrate ingredients close together on the ingredient list, your pet food is likely cutting corners on protein.
Best Sources of Protein for Dog Food
These sources of protein have a high biological value, and each of them contains all ten necessary amino acids for canine health. Foods with these best protein sources in the top 6 ingredients are likely high-quality dog foods.
Whole Eggs (BV 100)
With a biological value of 100, eggs win for protein quality. They are very digestible and one of the best protein sources for dogs. They are also a relatively cheap ingredient for their concentrated goodness, hence you will find them in most dog and cat foods.
Chicken/Turkey (BV 79)
The most biologically available of the fresh meats, chicken and turkey are winners for your pet’s food. The only problem is that chicken is one of the more common allergies that dogs and cats can have, mostly because of its prevalence.
To reduce the chances of your dog developing a chicken allergy, change up the main protein source in your pet’s food every few months. Other less-common poultry, such as duck, are also quality protein sources. If you have a puppy, introduce them to several protein sources in the first year of life to reduce allergy risk.
Salmon, Oceanfish, & Other Named Fish (BV 70)
Fish are a healthy source of protein for dogs, and have distinct benefits for dogs with sensitive or dry skin. Oils and omega fatty acids found within fish nourish and moisturize the skin, preventing flaking of skin and even shedding.
Since fish can contain high levels of toxins, it is important to rotate your pet’s primary protein sources if possible.
Beef (BV 69)
Beef is a healthy source of protein and is readily digestible. Other ruminating animals, such as lamb, sheep, venison, and bison are also quality sources of protein for pet foods, though their availability might make them a little more expensive.
Chicken or other Named Meat Meals
The AAFCO definition for chicken meal is the “dry rendered product from a combination of clean chicken flesh and skin with or without accompanying bone, derived from whole carcasses of chicken, exclusive of feathers, heads, feet and entrails.” Source: Wikipedia. The only thing that makes named meat meals a little less healthy is that they are rendered products, and their high-heat cooking method decreases the overall protein and nutritional value of the ingredient. That being said, meals can still deliver a highly concentrated protein source for your pet’s food.
Adequate Sources of Protein for Dog Food
These protein sources contain most (or all) necessary amino acids and have a moderate digestibility. Some grains and grain-free plant-based protein sources (such as brown rice or oatmeal) will actually increase the biological value of your pet food when paired with high-quality meats.
Chicken (or other named meat) By-Products
By-products are the ground up carcasses of animals, excluding meat and including offal, bones, and undeveloped eggs. These can include healthy organ meats, but more often contain low-quality proteins with limited digestibility. The reality is that by-products can vary widely in their nutritional value, making them an inconsistent choice for dog food. Relying on by-products as a primary source of protein for your pet is like playing a nutritional roulette.
Soy (BV 67-74)
Soy has a fairly high biological value for a legume, but there are plenty of reasons for its modest protein rating. Soy is a cheap legume that contains all necessary amino acids. However, it’s given a lower quality rating because soy is biologically inappropriate for dogs and cats, which means they would never encounter it in their wild diet. Also, some pets have sensitivities to soy and have a hard time digesting it due to their short digestive tract (in comparison to ours). Lastly, while soy isn’t the worst protein source, its very low cost is an indicator that your pet food is cutting corners when it comes to nutrition.
Other legume protein sources, such as lentils and chickpeas would also likely fall under this rating. A relatively new protein source in dog foods, lentils and other legumes, with their high fibre inclusion are a promising ingredient when it comes to dog weight loss. Their newness unfortunately means that they are not extensively tested in lifetime studies.
Plant-based sources of protein include potatoes (or potato protein), peas (pea protein), grains such as rice or oatmeal, quinoa, barley, and flaxseed. These are healthy ingredients for dog food, and your food is likely to include at least one of them (if not two or more) in the first 6 ingredients. What can be beneficial about these grain and vegetable-sourced proteins is that they often complement meat proteins, which means the overall biological value of the food goes up.
However, if there are several of these sources listed early on, it could indicate that your pet food has a lot less meat protein than you think it does. These plant-based ingredients are healthy for other reasons, but their offering of digestible protein is limited. One common cheap plant protein is corn or corn gluten. Be sure that if your pet food contains these ingredients, it also includes plenty of quality meat protein sources early on in the ingredient list as well.
Poor Sources of Protein
These sources of protein should be avoided. They do not contain adequate amino acids, or their amino acids have been altered for limited biological value. Foods that contain low-quality, cheap protein sources as primary protein sources are likely skimming in quality on other ingredients, too.
Meat By-Products and Meals
Meat and Bone Meal and other non-descriptive meat by-products are some of the lowest quality meat proteins available. Their high ash content is indicative of being difficult to digest and a low biological value. These “mystery meats” undoubtedly contain meat from the 4D’s (dead, diseased, dying, disabled), which can include restaurant leftovers, roadkill, supermarket castoffs (complete with packaging) and dead zoo animals – to name a few. These meat sources are undisclosed and can vary depending on the rendering plant, but are definitely the cheapest “meats” available. Avoid anything with the descriptive terms animal, poultry, blood, and meat.
Common Questions About Protein for Dogs
Is it possible to feed a vegetarian diet for dogs?
In short, yes. There are vegetarian and vegan dog foods out there. Dogs, like us, have very adaptive digestive systems. However, their short digestive tract still does not handle plant-based proteins as well as animal-based proteins, or meat. It would be impossible to stick with a biologically-appropriate diet by feeding your dog vegetarian or vegan, but your dog could still get the necessary nutrition.
That being said, a vegetarian or vegan diet does not give optimal nutrition to your dog. Legumes such as soy and lentils can be harder to digest, and not as biologically available as meat proteins. Your dog would have to eat more to get the appropriate nutrition. However, if your dog has severe allergies, a meatless diet may be a good nutritional choice for your pet.
Is it better to feed a limited ingredient diet (LID) or single protein diet instead of a standard one with multiple protein sources?
"Limited ingredient" is a bit of a misnomer, seeing as many LID diets still contain a fair amount of ingredients. The main difference between these diets and standard diets is that they contain usually one primary protein source and one primary carbohydrate source. The idea behind them was originally to support dogs with allergies. Generally, they include a novel protein (an unusual protein source that dogs are unlikely to have encountered, such as turkey), and carbohydrate (such as oats or rice). They generally stay away from common dog food proteins (and common allergy sources) such as chicken or beef.
These diets can be helpful for dogs who have developed allergies to common proteins. However, unless your dog is in this position, it's not recommended to feed a limited ingredient diet, unless you plan on switching it up frequently or mixing foods. The reason is this: feeding few protein sources (or just one) can actually encourage allergies to develop. Scientific studies have found that puppies fed a variety of foods in their first year are less likely to develop food allergies later on. And, the more different proteins that your pet has in his food, the more biologically available the food becomes to your pet, So, if your dog does not have any allergies, feed a variety of proteins to your dog regularly.
Protein is one of the most essential parts of your dog's diet. For total system functioning, make sure that the protein sources in your pet's food are high quality. High quality ingredients mean more nutrition and a healthier pet long-term. You can't skimp on nutrition without paying the price eventually!