Do Dogs Need Daily Multivitamin Supplements?

Published Sep. 30, 2011

Did you take a multivitamin or other nutritional supplement this morning? According to a 2009 Nielsen study, about half of us probably did. In the survey, 56 percent of U.S. consumers said they take vitamins or supplements, with 44 percent saying they take them daily.

I don’t have any statistics regarding the use of vitamin and mineral supplement in dogs, but I suspect it is pretty high based on the number of products that are available. But just because a product is readily available and widely used doesn’t necessarily mean that you should give it to your dog.

Like most things in life, vitamins and minerals are not wholly bad or wholly good. There are some instances when dogs should receive supplements. Here are a few:

Your dog has been diagnosed with a vitamin/mineral deficiency or a disease that responds to supplementation (e.g., zinc-responsive dermatosis or vitamin E supplementation for osteoarthritis). In most of these cases, you should be giving your dog specific vitamins and minerals, not a "multivitamin."

Your dog eats a home-prepared diet. To be nutritionally complete, you need to add a vitamin and mineral supplement to home-cooked foods. These recipes are best prepared under the advisement of a veterinary nutritionist.

Your dog is eating very little or will only eat a poor-quality diet. Whether this is because your dog is ill or just extremely finicky, a multivitamin can help ward off deficiencies in these situations. However, this is really a poor substitute for a better diet.

If your dog is eating a well-balanced and nutritionally complete dog food that is made from high-quality ingredients, a vitamin and mineral supplement is not necessary and could in fact do more harm than good. Why? Because reputable pet food manufacturers go to great lengths to make sure that your dog’s meals contain the right proportions of vitamins and minerals, and adding more can throw this delicate balance completely out of whack.

If you give your dog too much of a water soluble vitamin (e.g., vitamin C), he will just eliminate the excess in his urine. The biggest downside here is wasted money — "really expensive pee," is how I heard one nutritionist describe it.

But other situations aren’t so benign. Fat soluble vitamins (A, D, E, and K) are not so easily eliminated from the body and can build up to toxic levels. Oftentimes, an excess of a fat soluble vitamin is just as detrimental to a dog’s health as a deficiency. Furthermore, high levels of one mineral in the diet often interfere with the uptake of another. This is the case for phosphorus and calcium, copper and iron, phosphorus and sodium, zinc and magnesium, and more.

So, if your dog is healthy and eats well — a high-quality, commercially prepared food — you should not give him a multi-vitamin/mineral supplement. The information on the petMD Nutrition Center is a good way to see whether your dog’s food makes the grade.