Are Dog Vitamins and Supplements Really Necessary?

When it comes to dog vitamins and supplements there are basically two schools of thought:

1. If you feed your dog a commercial pet food that is labeled “100% complete and balanced” there is no need to give vitamins or supplements to your dog. In fact, doing so can be dangerous.

2. It is impossible to provide our pets with a diet that is 100% complete and balanced for their individual needs. Plus, vitamins added by the manufacturer of the food may be lost before the pet even eats it.

It shouldn’t surprise you that pet food manufacturers support the first school of thought while those in the business of selling dog vitamins and supplements support the latter.

There certainly is a lot of controversy and debate surrounding pet nutrition and human nutrition too, for that matter. Some argue that by breaking food down into its smallest parts, we are losing sight of the big picture. In his book, In Defense of Food, Michael Pollan calls this nutritionism–in other words, “the idea that a food is not a system but rather the sum of its nutrient parts.” Pollan also explains the power and weaknesses of this model. He says, “Scientific reductionism is an undeniably powerful tool, but it can mislead us too, especially when applied to something as complex, on the one side, as a food and on the other a human eater. It encourages us to take a simple mechanistic view of that transaction: Put in this nutrient, get out that physiological result. Yet people differ in important ways.”

Yes, dogs and cats differ in important ways too.

In order to tackle this debate we should first take a look at the role of vitamins in a dog’s diet. Vitamins are involved in chemical reactions of metabolism and function as enzymes, enzyme precursors, and coenzymes. So what does all that mumbo-jumbo mean exactly?

Basically, in order for your dog’s body to function properly, certain vitamins must be present in certain amounts. While there are “average” amounts that will be adequate for the majority of dogs, these exact amounts will vary from one dog to the next. Some vitamins are stored in your dog’s body for long periods of time while other vitamins are quickly utilized and must be replenished accordingly in the diet.

Many pet owners are concerned about not providing their pet with enough vitamins in the diet but dangers can arise when a pet is given too much of a certain vitamin as well. In fact, in an attempt to appear as “healthy” as possible some pet food manufacturers have been accused of over-supplementing their diets. Pet nutritionists often refer to this as “overnutrition.”

Unlike minerals which are inorganic in nature, vitamins are organic. An organic material is a substance that contains at least one carbon atom. Vitamins are the only organic molecule not classified as a protein, fat, or carbohydrate. Vitamins are not used as an energy source and are not structural components but instead play a key role in releasing energy provided by other nutrients.

Certain metabolic processes, including DNA synthesis, bone development, and tissue repair could not occur without the presence of certain vitamins. Vitamins also play a key role in other biological functions such as blood clotting and nerve signal transduction.

Vitamins are divided into two basic categories: fat-soluble vitamins (A, D, E, and K) and water-soluble vitamins (B complex and C).

Fat-soluble vitamins are stored in body fat and the liver. Therefore, dietary excesses over time can result in toxicosis. Water-soluble vitamins are not stored in the body to any great extent and must be supplied everyday in the diet. While water-soluble vitamins are required in very tiny amounts they are essential to many body activities, including the metabolism of proteins, carbohydrates, and fats. However, during periods of excessive water loss (diarrhea and excessive urination) supplementation may be necessary.

Keep in mind that there are many differences between the dietary requirements of humans, dogs, and cats. Vitamin requirements are no exception. This is especially important for those owners who are considering feeding a homemade diet.

When compared to dogs, cats have additional vitamin requirements. Cats are unable to convert beta-carotene, which is present in plants, into vitamin A. So, as a result, cats require a dietary source of preformed vitamin A which is only found in animal tissues. Niacin, or vitamin B3, must also be supplied in the diets of cats because they are unable to convert it from the amino acid tryptophan like dogs can. High amounts of niacin are found in meat, legumes, and grains.

Many commercial dog foods today also contain a range of antioxidant vitamins such as vitamins A, C, and E. These vitamins may help protect against the effects of premature aging and the onset and the progression of certain diseases. These antioxidants serve to destroy free radicals which are generated when a pet’s body uses oxygen to create energy. As your dog becomes older, this energy-creating process becomes less effective and increased numbers of free radicals are produced. So antioxidants become even more important for our senior pets.

So, that brings us back to our main question. Is supplementation really necessary for our dogs that eat a “complete and balanced” diet? Really, the answer depends on your dog. There are certain inherited disorders which may cause disease in dogs as the result of their inability to absorb, assimilate, or metabolize specific vitamins or nutrients. Other than that, I think most supplementation with vitamins is overkill. Why put something into your dog’s body that he doesn’t need? If he’s not exposed to ticks he doesn’t need a Lymes vaccine. If his body is responding well to his current diet, why change it? If you’re concerned that your dog may be “missing something” you should have a complete blood test performed by your veterinarian. Sometimes that’s the only way to know for sure. You wouldn’t give your dog a distemper vaccine if he didn’t need it right? The same is true with vitamins.

However, supplementation with other compounds such as glucosamine, chondroitin, and MSM may be more beneficial. There is also some research that supports the idea of supplementing aggressive dogs with tryptophan. But before you start your dog on any vitamin or supplement I would highly recommend having your veterinarian perform both a blood test and a urinalysis. Then, have those values rechecked 60 days later to check for any potential problems that may be caused by giving the supplement. I started giving my dog a glucosamine supplement only to find later on that it almost gave her bladder stones. Luckily I caught the problem early on, but if I hadn’t been monitoring her closely she may have needed surgery. Remember, just because everything looks fine on the outside, doesn’t mean it’s the same way on the inside! And that, I think, is the most important lesson of all!