Key Nutrients Your Dog's Diet Might Be Missing
I'm often asked to audit the diets of dogs who are eating raw or homecooked meals; their pet parents having discovered the wonderful health benefits of minimally processed nutrition. I'm happy to hear from people who are interested in dog diets - it's one of my favourite topics. However I see a large number of diets that are missing key nutrients.
Dogs have a set of nutritional requirements and it's a good idea to have some basic knowledge about which nutrients your dog needs and in what amounts. Puppies have a different set of nutritional requirements that we can talk about another time.
Recipes found online, in books, from friends, breed groups, passed down from family members, and even commercially available raw and cooked meals do not necessarily contain everything your dog needs to thrive.
A recipe or product that says it's "complete nutrition" might not be an accurate claim.
(Kibble, canned dog food, dehydrated, freeze dried or raw food products that have a statement that says the food meets AAFCO or FEDIAF requirements for the particular life stage of the dog or puppy will be "complete nutrition" and so you don't need to be concerned with missing nutrients. Typically, most products that meet AAFCO requirements will have added vitamins and minerals. Some commercially available raw or cooked dog food products might list their nutrient values per 1000 kcal which you can then compare with the nutrients required by your particular dog. I know... it's a bit confusing.)
This article, then, is for anyone who uses commercial raw or cooked dog food, or follows a recipe and there is no AAFCO or FEDIAF nutritional adequacy statement or no assurances that the food meets NRC recommended amounts. (The NRC - National Research Council - provides a set of nutritional guidelines for dogs and cats based on decades of scientific study and published research. It's not perfect, but at least it's a set of standards.)
I use the NRC guidelines to evaluate and create fresh food diets for dogs. The NRC approach uses two ways to report nutrients: one method is by how much of a specific nutrient is contained in the food or recipe per 1000 kcal; and the other method is a calculation based the body weight of an individual dog.
I've put together a summary of some key nutrients that are often low or missing in fresh food diets. Each nutrient really deserves its own article to fully describe the required amounts, function, and food sources, but I'll briefly touch on the main points and hopefully this will help you determine if your dog's diet is meeting requirements or if it needs some improvements. I will include the NRC recommended amount per 1000 kcal, along with my 85 lb. dog, Jake's requirements for each nutrient as a real life example. I will also list a few food sources for each nutrient.
Calcium is one of the most important minerals in a dog's diet. Calcium is needed for the formation and maintenance of bones and teeth, and it's needed for nerve transmission and muscle function. Your dog's heart is a big muscle.
The body makes sure that correct levels of calcium are maintained in the blood, and will draw calcium from the bones if necessary. Over time a calcium deficiency can cause your dog to have weakened bones, skeletal abnormalities and secondary parathyroidism.
It's not uncommon to see higher amounts of calcium in raw diets. For healthy adult dogs, this is not a serious concern to a point, as long as the calcium:phosphorus ratio is within range. The trouble is that excess calcium in the diet can interfere with the absorption of other minerals in the diet and this can cause nutritional deficiencies.
The NRC Recommended Allowance for adult dogs is 1 gram of calcium per 1000 kcals.
Jake's recommended allowance for calcium is about 2 grams daily.
In raw diets, raw edible bone is the most common source of calcium.
Since cooked bone must never be fed to dogs, look for a calcium supplement such as calcium carbonate or calcium citrate to be added in cooked recipes and meals. In general, calcium carbonate is very absorbable and a good choice for most dogs.
Some raw diets will use a calcium supplement if raw edible bone is not used. Eggshells and eggshell powder are sources of calcium as well, but you need to make sure that you are using appropriate amounts.
Dairy alone will not provide enough calcium to meet a dog's requirements. For example, 1 cup of 2% cottage cheese contains about only 206 mg of calcium while 1 cup of plain low fat yogurt contains 448 mg of calcium. Many dogs would not be able to comfortably digest this amount of dairy.
Vitamin D3 is an essential nutrient. It's required for the proper absorption of calcium and phosphorus and in the development and maintenance of bone tissue.
There is growing evidence that Vitamin D3 is tied to the immune system and low levels of Vitamin D3 are found in dogs with cancer, heart disease, joint disease, and inflammatory bowel disease.
More research needs to be done to determine whether disease and low levels of Vitamin D3 are correlation or causation. Regardless, we cannot gloss over a dog's requirement for Vitamin D3.
There are two types of Vitamin D: D2 which comes from plant sources, and D3 which comes from animal sources. D2 is not bioavailable for dogs, and so it's D3 that your dog requires.
Dogs can not make their own Vitamin D from the sun, and so it must be supplied in the diet.
The NRC Recommended Allowance for dogs is 3.4 mcg, or 136 iu per 1000 kcals.
Jake's recommended allowance for Vitamin D3 is almost 7 mcg, or 279 iu daily.
First, let's deal with a few misconceptions that I've seen circulating in dog nutrition circles.
Mushrooms, even ones that have been exposed to sunlight are not a bioavailable source of Vitamin D for dogs. Oysters and mussels are also not good sources of Vitamin D3. There are other excellent reasons to include oysters and mussels in a dog's diet, but their Vitamin D3 content is not one of them.
The USDA nutrient data base lists the Vitamin D content of 100 grams of cooked, canned oysters as 0 mcg.
The USDA nutrient data base lists the Vitamin D content of 100 grams of raw blue mussels as 0 mcg. I had to use the raw information even though you'd never feed raw mussels to dogs.
The USDA nutrient data base lists the combined amount of D2 and D3 of 100 grams of raw mushrooms at .2 mcg. That is an insignificant amount of Vitamin D. Side note, mushrooms need to be cooked before being fed to dogs.
Food sources of Vitamin D3 include:
Sardines - 28 grams contain about 45 iu or just over 1 mcg.
Wild caught salmon - 28 grams contain about 282 iu or about 7 mcg.
Canned Sockeye salmon - 28 grams contain about 149 iu or about 3.7 mcg.
1 large egg yolk - 40 iu, or 1 mcg.
28 grams of beef liver and 28 grams of turkey liver - 14 iu each approximately. This is quite a small amount of Vitamin D3.
Interestingly, the Vitamin D3 content of liver depends on where the animal is raised. Animals that are allowed to live outdoors exposed to sunlight have higher concentrations of Vitamin D3 in their livers than factory farmed animals who spend their lives indoors. Chicken liver contains almost no Vitamin D3 and 28 grams of cooked pork liver contains a tiny 3 iu of Vitamin D3.
Fish body oils generally contain only small amounts of Vitamin D3.
Cod liver oil has a high amount of Vitamin D3, but also a very high amount of Vitamin A. Only use cod liver oil under the guidance of a canine nutrition professional, or your veterinarian.
Vitamin D3 can be toxic in high amounts and there is a safe upper limit. Excessive amounts of Vitamin D3 can damage a dog's kidneys and even cause death.
If you need to rely on a supplement to meet your dog's Vitamin D3 requirements it must be done under the guidance of a competent canine nutrition professional or your veterinarian. Vitamin D3 supplements intended for human use are not appropriate for dogs since it's likely they will contain very high amounts of the vitamin.
Here is an excellent study on the correlation between the effects of low levels of Vitamin D in dogs and health and cancer risk.
Manganese is a trace mineral that's involved in nutrient metabolism, acts as part of the body's antioxidant system and is needed for cartilage and joint health.
In the wild, carnivores would get manganese from the feathers, hair, wool, and testes of their prey, so pet parents need to compensate the diet in other ways.
The NRC Recommended Allowance for adult dogs is 1.2 mg per 1000 kcals.
Jake's recommended allowance for manganese is about 2.5 mg daily.
A few sources of manganese include:
28 grams of raw green tripe - .37 mg. (source).
28 grams of cooked blue mussels are a very good source of manganese containing1.9 mg.
28 grams of wild blueberries contain .8 mg. as listed on nutritiondata.com.
28 grams of frozen, chopped spinach contains .2 mg.
Other sources of manganese include pumpkin seeds and hemp seed hearts, but they have lower bioavailability for dogs and I question how well dogs can tolerate seeds. I also question the impact to the diet overall if a large amount of seeds are fed to fulfill manganese requirements.
If you are feeding cooked grains manganese can come from quinoa and brown rice.
Some joint support supplements contain manganese. Manganese supplements are a good idea if your dog cannot tolerate food sources of manganese. Manganese supplements have a fairly low absorption level and so we can go over the Recommended Allowance.
Iodine is a trace mineral that supports the thyroid gland. Your dog's thyroid gland produces hormones that regulate metabolism, growth, heart rate, and even mood. Thyroid glands that are not working properly in dogs can create issues with the skin and coat, weight gain, and energy levels. Over time an oversupply or an undersupply of iodine can negatively affect your dog, so it's important to get this number correct.
The NRC Recommended Allowance for adult dogs is 220 mcg per 1000 kcals.
Jake's recommended allowance is almost 460 mcg daily.
Kelp is an iodine rich sea plant that is commonly used to add iodine to the dog's diet. The iodine content of kelp can vary significantly though and it's important to choose a 'clean' source since kelp can contain trace amounts of heavy metals.
Often I will see kelp in the ingredients list of commercial raw products or homecooked recipes but no indication of how many mcg of iodine is actually in the food. In this case, you can contact the manufacturer and ask for information, but it may not be available. I know... it can be frustrating.
Omega-3 fatty acids from Marine Sources
It's important to include Omega-3 fatty acids from marine sources, named EPA and DHA, in the dog's diet. These two fatty acids decrease inflammation, support the immune system, benefit the heart, joints, brain and skin and coat.
EPA and DHA come from fatty fish such as sardines, herring, anchovies, salmon, mackerel and krill. Oils made from the body oils of fatty fish also supply EPA and DHA.
Plant sources of omega-3s such as flaxseed oil and hempseed oil contain ALA. The dog's body must convert ALA to the more usable forms of EPA and DHA. Dogs are inefficient at this conversion process and so only a fraction of ALA is actually usable by the dog. Use plant sources of omega-3s if your dog is allergic or intolerant of fish, but do not rely on them to supply EPA and DHA.
There are numerous scientific studies that show the importance of including EPA and DHA in the diet, but the NRC hasn't caught up with the science yet and doesn't provide recommendations for optimal amounts to include in an adult dog's diet.
Some canine nutrition professionals suggest a dose of 10 mg - 30 mg of EPA and DHA combined per pound of dog daily, depending on the dog, tolerance, diet, health etc. Natural sources of Vitamin E will be required when omega-3 increases in the diet.
If you are using a high quality fish oil following the suggested dose on the label is also a good plan.
It's important to get guidance from your veterinarian or canine nutritionist on the amount of omega-3s best suited for your dog.
Click here for tips on keeping fish oil fresh.
I hope this guide helps you figure out what nutrients might be missing from your dog's diet.
Sometimes pet parents will tell me they feel badly that they have made "mistakes" when feeding their dogs, but I never want someone to beat themselves up over things they didn't know. The fact that you are reading about dog nutrition is an excellent step, and once you know better, you can do better!
The USDA Nutrient Database and NutritionData were used for nutrient information for this article unless otherwise noted.
This information is for healthy adult dogs. Puppies and dogs with health concerns may/will have other nutrient requirements. When in doubt I recommend that you contact a qualified canine nutrition professional for guidance.