Vim and Vigor: The Right Supplements Can Enhance Your Dog's Diet
Cook's Corner column by Mary Straus, published in Dog World Magazine, September 2010.
A homemade diet that includes a wide variety of foods in appropriate proportions should meet your dog’s nutritional needs, but supplements can provide additional benefits.
Essential Fatty Acids (EFAs)
Omega-3 and omega-6 fatty acids are called essential because they must come from food; the body cannot manufacture them.
Omega-3 fatty acids provide many benefits, such as regulating the immune system, maintaining skin and coat health, reducing inflammation, and supporting brain development. They are found primarily in fatty fish and fish oils, as well as certain plant oils, particularly flaxseed. Omega-3s are found primarily in fatty fish and fish oils, as well as in certain plant oils, particularly flaxseed.
Omega-3 fatty acids come in different forms: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in fish oil, while alpha-linolenic acid (ALA) is found in plant oils. To utilize ALA, the body must first convert it to EPA and DHA. Because dogs perform this conversion poorly, fish oil is a much better source of omega-3 fatty acids for them.
Omega-3 fatty acids quickly become rancid when exposed to light, heat or air, so liquid fish oil should be refrigerated and stored in dark bottles. Fish oil is also available in gelcaps that contain 200 to 600 mg combined EPA and DHA.
Fish oil supplements are suggested for all dogs; most diets lack omega-3 fatty acids.Give healthy dogs about 300 milligrams combined EPA and DHA per 30 pounds of body weight daily. This dosage can be increased to 300 milligrams per 10 pounds of body weight for dogs suffering from cancer, kidney disease, arthritis, allergies, or other inflammatory and immune-mediated diseases.
If you prefer, include fatty fish in your dog's diet rather than fish oil. Include about 1 ounce of canned sardines, jack mackerel or pink salmon per pound of other meats.
Unlike fish oil, cod liver oil is high in vitamins A and D. Cod liver oil is not needed if you feed liver, but it should be added to homemade diets that do not include liver. Give about 100 IUs vitamin D per 20 pounds of body weight daily. Too much vitamin A can be harmful if given long-term, so never give mega doses of cod liver oil.
Omega-6 fatty acids are found mostly in plant oils, such as safflower, canola and corn oil, as well as in poultry fat. Linoleic acid, the primary omega-6 fatty acid, is plentiful in most diets. There's no need to add plant oils unless you feed a diet that's very low in fat, or if you feed only beef and other ruminant meats (not poultry), because they are low in linoleic acid.
Adding oils to the diet increases vitamin E requirements. See Vitamin E for my current recommendations on vitamin E supplementation..
Probiotics are beneficial bacteria that improve digestive health. Give probiotic supplements to dogs with digestive problems and following antibiotic treatment. Regular use may benefit healthy dogs as well. Use supplements designed for either people or dogs .
We don’t know for certain which probiotic strains work best. Two that have been shown to benefit dogs are Enterococcus faecium and Fortiflora from Purina (best price at EntirelyPets) and Bacillus coagulans (formerly called Lactobacillus sporogenes; available at Amazon). Bifidobacterium animalis (found in Probiotic Miracle from Nusentia, available at Amazon) has also been shown to reduce the time for acute diarrhea to resolve. Several canine probiotic supplements, such as Jarrow Formula's Pet Dophilus Powder and Fortiflora from Purina (best price at EntirelyPets), contain Enterococcus faecium. (Note that despite its proven beneficial effects, E. faecium may be best used short-term due to possible issues with antibiotic resistance, opportunistic infections such as UTIs, and effects if transmitted to humans. Strain SF68 appears to be safer than other E. faecium strains.)
Yogurt and kefir are cultured milk products that provide probiotics. Products with added strains (not just Lactobacillus acidophilus, the most common probiotic strain) might be particularly helpful.
Some probiotic supplements also add indigestible fiber (prebiotics) which feed the beneficial bacteria. Examples include chicory, inulin, larch and FOS (fructooligosaccharides). Prebiotics may help dogs with diarrhea and those with overgrowths of harmful intestinal bacteria.
Digestive enzymes help some dogs with gastrointestinal disorders. Give digestive enzymes only if they seem to benefit your dog. Plant-based enzymes might work best if you feed a diet that includes a lot of carbohydrates (grains and starchy vegetables). Animal-based enzymes derived from pancreatin (a mixture of digestive enzymes derived from animal sources) may be the better choice for diets that are high in meat. The enzymes bromelain and papain can help with gas and inflammation.
Vitamins and Minerals
A “complete” multivitamin and mineral supplement provides some assurance that your dog receives all of the necessary nutrients. Various supplements provide varying amounts of vitamins and minerals. Don't rely on a supplement to complete a very limited diet, unless the supplement was designed to do so. As long as you’re feeding a wide variety of foods, including meat, organs, eggs, fish and vegetables, don't worry about the exact nutrient levels in the supplement you use.
You can give dogs that weigh more than 25 pounds supplements designed for either humans or dogs. Adjust human supplements for the weight of your dog: give half the human dose to dogs that weigh 50 pounds, and one-quarter dose to dogs that weigh 25 pounds. For smaller dogs, use supplements made for dogs to ensure you're giving the right dosage.
Some minerals, such as zinc and selenium, can be dangerous if overdosed or not properly balanced with other minerals. Don't exceed recommended dosages or give individual mineral supplements without your vet's OK.
It’s better to rotate between different supplements rather than always giving the same ones. Different supplements provide different nutrients; rotating means you’re less likely to give too much or too little of a particular vitamin or mineral.
Supplemental nutrients can be either synthetic or natural. Whole-food supplements tend to provide lower levels of vitamins and minerals than synthetics, but the nutrients are more complete and bioavailable (able to be absorbed and used by the body). You can rotate between the two to provide the best of both.
Good whole foods to add to your dog’s diet include nutritional or brewer’s yeast (a good source of B vitamins), kelp, organic apple cider vinegar, raw honey, ginger (good for digestion), blackstrap molasses and fresh crushed garlic. Too much garlic can cause anemia in dogs; give no more than one-half of a small clove per 20 pounds of body weight daily. Kelp is high in iodine, which is needed for thyroid health, but too much iodine can suppress thyroid function. Give no more than ¼ teaspoon kelp to a large dog (about 60 pounds or more), and proportionately less to smaller dogs.
Green blends are mixtures of plant foods and herbs such as alfalfa, kelp, spirulina and other sea vegetables, wheat grass and fenugreek seed. These foods provide antioxidants, minerals and other beneficial nutrients. While they can be added to any diet, I think they are especially important if you do not feed green vegetables.
Your Dog’s Needs
Choosing the best supplements depends on your dog’s diet and health. The more limited the diet, the more supplements are necessary to meet your dog’s nutritional needs.
You can contact me if you have any comments, but I regret to say that I can no longer respond to questions about individual dogs. See my Contact page for more information. My name is Mary Straus and you can email me at either or