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Does My Dog Really Need Supplements?

Many people take supplements themselves, such as vitamins, minerals and nutraceuticals (pharmaceutical-grade nutrients), so as veterinarians, we often get asked whether pets need them too. The answer is a bit complicated and ends up being a “sometimes yes and sometimes no” kind of thing.

While you might take a supplement yourself and swear that there is a perceived improvement in your own health, for many reasons there is often scant scientific evidence that supplements have any real effect on wellness. Most of these substances cannot be patented because they aren’t synthesized in a lab or manufacturing process, so there is little in the way of monetary gain to make costly and lengthy research worthwhile. And the lack of any kind of formal and government-enforced quality monitoring procedures makes it difficult to feel confident that you’re even getting what you think you are when you buy these products.

Read on to learn which supplements may be helpful, which ones can’t hurt and which ones may in fact be harmful for your dog.

Omega-3 fatty acids

We have more solid scientific evidence about the benefits of omega-3 fatty acids than virtually any other nutritional supplement. Specifically, polyunsaturated fats such as DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are felt to be beneficial as a treatment for the itchiness associated with allergic skin disease. They may also help reduce inflammation associated with arthritis in diseases like hip dysplasia. Recent evidence even suggests that they may slow the rate of dysfunction associated with chronic kidney disease.

Dogs can take fish oil capsules directly by mouth. Always choose a brand formulated for dogs. Some dogs prefer to have the oil put on their food, and there are products that can be pumped directly onto the food, as well as capsules designed to have the ends snipped so that the contents can be squeezed onto the food. There are also dog foods, specifically targeted for use in arthritic dogs that have high doses of omega-3 fats. If you choose to feed your dog one of these diets, ask your veterinarian about using a prescription diet or make sure that the brand you buy contains appropriate preservatives in order to increase the shelf life of these somewhat volatile oils.

A word of caution: High levels of omega-3 fatty acids may cause platelet problems, which can contribute to prolonged bleeding times after injuries or surgical procedures, so always let your veterinarian know that your dog is taking an omega-3 supplement.

More: Do you need to worry about BPA levels in your dog?

Joint supplements

Joint supplements disguised as tasty treats for dogs have been on the market for many years. Most of them contain glucosamine and chondroitin, and some also contain MSM (methylsulfonylmethane) and green lip mussel extract. There are many proprietary formulations of some or all of these ingredients.

The evidence that these supplements improve joint health is less convincing than for the benefits omega-3 fats to allergic dogs; however, many pet parents do feel that they see improvement with them. It’s believed that these ingredients contain the components necessary to build cartilage, so in diseases that involve cartilage destruction, such as osteoarthritis, they may provide some benefit. These products seem to be most helpful when started early in the disease process, so don’t expect much in the way of improvement if your dog is already painful when you start these.


As long as your dog is eating a high-quality commercial canine diet, he should not need to take a vitamin and mineral supplement. Canine diets are formulated to meet the dog’s daily requirements of those substances.

If your veterinarian has helped you develop a home-cooked diet for your dog or you’ve used the excellent veterinary nutritionists at BalanceIT to do so, you will likely need to add a multivitamin to his daily regimen. Most dependable home-cooked recipes contain recommendations as to which multivitamins are appropriate and how much to give daily.

More: 15 Toxic Foods Every Dog Owner Should Know


Silymarin is also known as milk thistle. There is quite a bit of evidence, both in human and veterinary medicine, that it aids in the clearance of toxins in the liver. In Europe, dogs that have ingested poisonous mushrooms are routinely given the injectable form of this substance in order to correct the liver damage that occurs, but this form of silymarin is not available in the U.S.

We don’t have any reliable studies to suggest that dogs with normal liver function benefit from silymarin; however, it seems to be safe, and it’s likely that using it in a healthy dog would not be problematic. It’s believed that silymarin changes the metabolism of other drugs, so it’s best to consult with your veterinarian before starting to give it to your dog.


Fiber supplements can be beneficial in dogs that have chronic diarrhea or chronic constipation. Psyllium husks can help to normalize the stool, both in the cases of routine diarrhea and with dogs that have problems defecating due to constipation. Psyllium husks are safe to use and can be given at a rate of one teaspoon per day for small dogs and one tablespoon per day for big dogs. Metamucil is mostly psyllium, so it can be used, but read the ingredient list carefully, as many varieties contain sugar, and it’s best to avoid excess dietary sugar, if possible.


Many people use 5-hydroxytryptophan to treat depression, chronic headaches and insomnia. It may even have some mood-altering benefits in dogs. However, in the doses that are routinely put into one capsule for a human, this substance can be deadly to our canine friends.

In large quantities, 5-HTP can trigger a condition known as serotonin syndrome. Because 5-HTP is readily absorbed in the GI tract, dogs can experience fatal neurologic and GI problems related to ingestion of it. If you use 5-HTP yourself, be hyperaware of how and where you store your supply, and make sure it’s well out of reach of your dog.

More: All of Your Dog Tongue Questions Answered

Calcium supplements

Commercially prepared dog foods are appropriately balanced for calcium and phosphorus, the two minerals that are essential for healthy bone growth and production in the body. While these minerals are of the utmost importance to puppies, they are important during the dog’s entire life because bone is continually being broken down and produced.

Giving oral calcium supplements to a healthy dog, in addition to the calcium that is consumed in the diet, puts the dog at risk for developing calcium deposits in the body. The most likely place for calcium to gather is in the urinary tract, and calcium supplementation can predispose a dog to the development of kidney and bladder stones.

If you’re making a home-cooked diet for your dog, using the right amount of calcium is critical to preventing the buildup of calcium excess in the body. Using a recipe developed by veterinary nutritionists will ensure that the diet is properly balanced.

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