The choice of whether or not to add supplements is an individual one. Healthy dogs fed a wide variety of fresh foods in appropriate proportions should have no need of supplements, though they may still benefit from them. The less variety you feed, the more necessary supplements become. Cooked diets are more likely to need supplements, since cooking destroys or reduces some nutrients. Dogs with health problems may also benefit from certain supplements regardless of their diet.

The most important supplement is fish body oil (not cod liver oil), such as salmon oil or EPA oil. This supplies omega-3 fatty acids, which provide a variety of benefits and are hard to find in any diet, whether homemade or commercial. The recommended dosage for healthy dogs is around 1 gram (1,000 mg) of fish oil per 20 to 30 pounds of body weight (dogs with certain health problems may benefit from higher doses). You can also use sardines in place of fish oil. Two or three small sardines supply as much omega-3 fatty acids as one gram of fish oil.

When fed in doses high enough to supply the recommended amount of EPA and DHA, cod liver oil would contribute too much vitamin D. Restrict the amount of cod liver oil you feed your dog so that it does not contribute more than 100 IUs daily for a small dog, to 400 IUs daily for a large dog. Do not add cod liver oil or other sources of vitamin D to any commercial diet, as most are already high in vitamin D.

Note that flaxseed oil and carmelina oil are not good choices to replace fish oil, as the form of omega-3 fatty acids found in plant oils (alpha linolenic acid, or ALA) must be converted in the body to the forms that dogs can utilize (EPA and DHA). At best, dogs probably convert 15 percent of ALA to EPA and DHA; at worst, none of it. Fish, grass-fed meats, and eggs are also good sources of omega-3 fatty acids.

Whenever you add oils of any kind, you need to supplement with vitamin E, or the body will become depleted of this vitamin over time. Give around 100 IUs to a small dog (under 25 lbs), 200 IUs to a medium-sized dog (25 to 60 lbs), and 400 IUs to a large dog (more than 60 lbs), anywhere from daily to once a week.

Because dogs can make their own vitamin C, this vitamin is not considered essential, but that ability may be reduced during times of stress or illness, and additional vitamin C may provide benefits even to healthy dogs. Similarly, dogs may be able to get vitamin D from sunlight as people do, but during winter months, this may not be enough. Dogs that are kept primarily indoors or that have heavy coats may also get limited vitamin D from sunlight.

Minerals are tricky to supplement, as they can be dangerous at excessive levels, or if they are not balanced properly with other minerals. For example, zinc binds with copper, so if you give a supplement long term that includes zinc but not copper in proper proportions (10:1), eventually this can lead to a copper deficiency.

Minerals are most safely supplemented in whole food form. Green blends that contain foods such as kelp, spirulina, Irish moss, fenugreek seed, and alfalfa are an excellent source of trace minerals. (Note that it is important not to give too much kelp, as it is high in iodine and too much can suppress the thyroid.) It’s best to give kelp in very small amounts — ¼ teaspoon or less for a large dog.

Organic apple cider vinegar, nutritional or brewer’s yeast, and dark molasses also supply trace minerals. Other fresh food supplements that may provide benefits include raw honey, ginger (especially good for digestion), and fresh crushed garlic (no more than 1 small clove per 20 pounds of body weight daily; more can cause anemia).

You may want to add probiotics, especially if your dog is stressed or ill, has been treated with antibiotics, or has had diarrhea. Supplements with multiple strains of beneficial bacteria are preferable to plain acidophilus; Lactobacillus spirogenes and Enterococcus faecium are two that may be especially good for dogs. Digestive enzymes are also helpful for some dogs with gastrointestinal problems.


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