Most of us know that protein is an essential nutrient for all animals. Protein is the main building blocks of most animal tissue (e.g. muscle, skin, tendons, and even hair and fur). It is also involved in the healthy functioning of various body systems, such as the immune system, the endocrine system, the circulatory system and more. Protein also provides energy, helps with the repair of injured tissues, and supports muscle growth (an important consideration is you’re raising a puppy.)
Puppies and lactating females need a higher protein diet than most adult dogs
So with all these wonderful benefits, it would seem that feeding your dog a high-protein diet would always be a good thing. And based on the proliferation of high-protein diets on pet store shelves, it would appear that many dog parents agree. Yet the truth is that high-protein diets are not a good choice for every dog. In fact, there are a number of situations in which a low protein dog food is preferable for your dog. But before we look at those specific scenarios, let’s take a closer look at what dietary protein is and what it does.
- What Is Protein?
- Sources of Protein for Dogs
- Protein Metabolism in Dogs
- What Is Low Protein Dog Food?
- When to Feed Your Dog a Low Protein Dog Food
- The Best Low-Protein Dog Foods
- The Bottom Line
What Is Protein?
Protein is a term that encompasses a large range of organic compounds made up of chains of amino acids, which are held together by peptide bonds. A short chain of two amino acids held together by one peptide is called a dipeptide, while a chain of three amino acids held together by two peptides is a tripeptide. A chain of more than 10 amino acids is called a polypeptide. Virtually all dietary proteins are polypeptides whose shape and size depends on the number of peptide bonds and the amino acids they contain.
Amino acids are classified further as essential or nonessential. Nonessential amino acids can be made in sufficient quantities by the body and, to some extent, stored for later use. Essential amino acids are those that the body can’t manufacture or store; they must be obtained through diet. All animals require different essential amino acids. Dogs require these 10:
Many pet food manufacturers also add additional amino acids to their foods that are believed to be of some benefit to dogs. These include:
- L-lysine monohydrochloride
- Taurine (essential for cats but is sometimes added to dog food)
Sources of Protein for Dogs
Protein is found in all animal products and many edible plants. And while many of us think of dogs as carnivores whose major protein source should be meat, they are, in fact, omnivores who can eat and digest all sorts of foods, including meat, vegetables, fruits and grains. That’s one reason why many pet food manufacturers rely on plant proteins (which are less expensive than meat) to beef up the protein content in the foods they sell.
Dogs need complete proteins derived from animal sources such as meat, fish and eggs to stay healthy and active.
With that being said, all dietary protein is not created equal. Plant and animal proteins differ in the amount of “usable” protein they contain. In other words, dogs digest some protein sources more easily than others, and get more or fewer nutrients as a result. Eggs, turkey and chicken, for example, are extremely digestible (this is often referred to as bioavailability) and are, therefore, excellent protein sources for dogs. They are also considered “complete proteins” in that they contain all of the essential amino acids your dog needs (Fish, beef, lamb and meat by- products such as organs, blood and bone are also complete proteins.)
Plant proteins, on the other hand, are typically less digestible than animal products, and often contain only some of the amino acids a dog needs to get from food. Grains such as corn, rice, wheat, oatmeal and barley, and legumes such as peas and lentils are just a few of the “incomplete” proteins that are typically included in commercially prepared dog foods. These ingredients also contain high concentrations of carbohydrates, which are metabolized more quickly and can provide a quick burst of energy when your dog is having an active day (think of athlete’s carbo-loading before a race.) But precisely because carbs are so easily digested, they are quickly converted into sugar, which, if it’s not used very quickly, turns to fat. Given the number of American dogs who are overweight or obese (up to 50% according to VCA Animal Hospitals) that’s a significant concern.
Protein Metabolism in Dogs
When a dog digests protein, it’s absorbed from the intestines and then broken down by the liver into peptides and free amino acids. The amino acids are then transported through the bloodstream to various parts of the body,where they are used to make new protein molecules. Some examples of these bodily proteins include immunoglobulins (antibodies), which are essential to fighting infection; lipoproteins, which transport cholesterol in the blood; and hemoglobin, which transports oxygen throughout the body via red blood cells.
The breakdown of protein also produces ammonia, which is toxic to both humans and dogs. In order to prevent ammonia from damaging healthy tissues, the liver converts it to a water soluble compound called urea. Some urea is reabsorbed by the liver, but most is excreted by the kidneys in urine and through the intestines in bile.
Overweight senior dogs like this pup may benefit from a low-protein dog food or one with a moderate amount of protein and few carbs.
What Is Low Protein Dog Food?
Although dogs’ nutritional needs can vary a great deal, most veterinarians and vet nutritionists recommend that healthy adult dogs consume about 18% – 20% of their total caloric intake as protein. It’s important to note, however, that this percentage is based on the amount of “dry matter” in the dog’s food — that is, the quantity of food minus the moisture it contains. This is not how the concentration of nutrients is reported on pet food labels, however. The Guaranteed Analysis you see on the label only lists the percentages of protein, fat, fiber and moisture based on what’s in the can or bag (also known as the “as fed” basis”). So if the food contains a lot of moisture, the percentage of protein on the label may seem quite low when it is actually high.
To determine how much protein is in any dog food, therefore, you need to do a little bit of math.
Let’s look at this hypothetical dog food label as an example:
To determine the amount of protein in this food on a dry matter basis, you need to:
- Start by determining the amount of dry matter in the dog food. This food contains 80% moisture and 20% dry matter (100%-80%=20%).
- Now, divide the dry matter amount by the percentage of protein the food contains. (20/10=2).
- Finally, multiply the result by .100 to obtain the actual protein percentage per dry matter basis in the can. (2x.100 =20%).
Thus, the food actually has a much higher protein concentration than the label would suggest.
With that being said, consensus among veterinarians about what constitutes a low-protein dog food doesn’t really exist. The AAFCO recommends 18 % protein per dry matter basis for adults and 22% for puppies and lactating females. However, the exact amount any dog needs depends on its general condition, age, activity level and breed. So, always check with your veterinarian before switching your dog to a lower protein food.
When to Feed Your Dog a Low Protein Dog Food
While most dogs will thrive on a balanced diet with the right balance of essential nutrients, some dogs have special needs that may include a low-protein diet. These include dogs with chronic kidney disease, or CKD, and dogs with chronic liver disease.
Chronic Kidney Disease
Chronic kidney disease or chronic renal failure, as it is sometimes called, occurs when a dog’s kidneys no longer perform the vital function of filtering waste products from the blood. Although kidney failure can happen suddenly, such as when a dog ingests a toxic substance like antifreeze or grapes. chronic kidney disease is a usually seen in older dogs whose kidneys are just “wearing out.” Chronic infections, particularly oral infections due to tooth and gum disease can also predispose a dog to chronic kidney failure. But in most cases, CKD has no specific cause.
Dogs with kDogs with kidney disease need a low-protein dog food with low amounts of copper and fat.
When a dog’s kidneys stop working properly, several things happen physiologically. First, the body recognizes that waste products are building up to unsafe levels, so it increases the kidneys’ blood supply in an attempt to get them to filter more toxins out. This causes the kidneys to produce more urine, and the dog urinates more. This excess fluid loss leads to dehydration, so the dog drinks more to compensate. At the same time, blood levels of certain waste products begin to increase. The most significant of these are creatinine, a by-product of muscle breakdown, and urea, which is measured in the blood as blood urea nitrogen, or BUN.
As we explained earlier, urea is a soluble compound made by the liver to facilitate the excretion of ammonia, a product of protein metabolism. Thus, limiting the protein intake of dogs in renal failure helps to keep BUN levels low and has long been a mainstay of dietary management of the disease. According to the National Research Council, the total protein intake for a dog with CKD should be between 14 and 20%. This recommendation, however, has engendered some controversy in recent years, as some veterinarians believe that it can lead to malnutrition and muscle wasting, especially in frail, elderly dogs. For this reason, it’s never a good idea to cut back on the protein in your dog’s diet without consulting with your vet first.
Chronic Liver Disease
Liver disease in dogs is less common than kidney disease, although it is a fairly regular finding in dogs in the later stages of life. Unlike acute liver failure, which is typically caused by infection (hepatitis) or the ingestion of toxins, chronic liver disease is usually associated with other health challenges such as diabetes. Cushing’s disease or thyroid disease. Symptoms of chronic liver disease usually develop slowly — about 80% of liver function may be lost by the time a dog appears ill.
With good veterinary care and the right dog food, a dog with liver disease can lead a long, healthy, active life.
Nutrition is very important for dogs with liver disease, and feeding the right amount of the right kind of protein is critical to their health. The liver is responsible for metabolizing dietary protein, so when the liver is damaged, the dog’s need for high-quality protein is increased. At the same time, the metabolism of protein leads to the formation of ammonia, which can lead to a serious and potentially fatal condition known as hepatic encephalopathy. So restricting the total amount of protein fed while optimizing essential amino acids is key. Additionally, dogs with a specific form of liver disease known as copper storage disease need a diet that’s low in both copper and protein. For this reason, it’s important to work closely with your veterinarian to determine what is the most appropriate dog food for your dog.
The Best Low-Protein Dog Foods
Because the amount of protein in dog food is regulated by the AAFCO, most low-protein dog foods require a prescription from your vet. It should be noted, however, that some of these prescription diets contain more protein than is recommended for dogs with kidney and/or liver disease by the NRC. With that being said, the following choices contain a balanced blend of nutrients, an appropriate amount of highly digestible protein and sufficient calories for most dogs.
Hills Prescription LD Diet Hepatic Health
One of the most recommended low-protein dog foods for dogs with liver disease, Hills Prescription LD Diet contains approximately 18.5% protein (dry matter basis) which falls well within the 14%- 20% recommended by the NRC. It also contains low levels of phosphorus, which can delay the progression of kidney disease, and a blend of Omega 3 and Omega-6 fatty acids, antioxidants which help protect the liver and promote overall health. It is available in both dry and wet forms, and if for some reason your dog doesn’t tolerate it or like it, you can return the remaining portion for a full refund.
Royal Canin Canine Renal Support S
With approximately 11% protein on a dry matter basis (10.5% as fed) Royal Canin’s renal support formula is one of the lowest protein dog foods available for dogs with kidney disease. It is marketed as a more palatable option than most dry dog foods (the “S” stands for “savory”), which may be beneficial for a dog who has a less than hearty appetite, which is not uncommon in kidney disease. The formula is also low in phosphorus and contains a blend of antioxidants including EPA and DHA (Omega-3 fatty acids) and vitamin E.
JustFoodForDogs Veterinary Diet Hepatic Support Low Fat Fresh Frozen Dog Food
Founded in 2010 by a team of veterinarians and veterinary nutritionists, JustFoodForDogs features fresh-frozen human grade ingredients in all of its foods. Its hepatic support formula is low in fat and contains about 17% protein, low amounts of copper, and very little sodium, as well as the antioxidants DHA and EPA. The company also offers a renal support option for dogs with kidney disease, which contains about 13% protein and low amounts of sodium and phosphorus. You can order the food directly from the manufacturer or through Petco, Chewy.com or Pet Food Express.
Purina Pro Plan NF Kidney Function Dog Food
If your dog needs a low-protein diet and prefers canned food, Purina Pro Plan NF Kidney Function dog food may be a good choice. A prescription diet like those shown above, it has a much higher moisture content than kibble, which may help keep your dog hydrated if his water intake is less than optimal. It contains about 15% protein on a DM basis (3.8% as-fed) and is low in both phosphorus and sodium, the latter of which can contribute to high blood pressure in some dogs with kidney disease. If you’d like to feed your dog a mixture of canned food and kibble, this formula is also available as a dry food that has about the same nutrient profile as the canned variety.
No matter what your dog’s age or physical condition, feeding him the right amount of protein and a nutritious diet will help him live his best life.
The Bottom Line
All dogs need protein to stay healthy and active, but the amount and type of protein any one dog needs is affected by his health status, activity level and his age. Most adult dogs will do well when fed a moderate amount of protein derived mostly from animal sources such as meat, fish, and eggs. Very active dogs, lactating females and growing puppies typically need more protein, and, as we just discussed, some dogs with chronic health issues need less.
Whether your dog is young and healthy or a senior with health issues or somewhere in between, good nutrition is essential to maintaining his quality of life. For that reason, we recommend that you speak with your vet regularly (at least at every wellness visit) about the best food for your dog.