As recently as 1990, supplements were relatively rare in the realm of companion animals. Calcium might be used to help German Shepherd ears stand upright, and glucosamine was gaining popularity for treating joint problems, but these were the exceptions.

The 21st century brought change. Since 2000, the pet supplement market has grown approximately 15 per cent each year, and in 2007 represented a $1.3 billion industry. A market research report found that 17 per cent of pet dogs receive some type of supplement.

Does your puppy need a supplement to achieve optimum health? Deb Eldredge, D.V.M., in practice in upstate New York and author of Pills for Pets, says, “The healthy pup on a balanced diet should not really need any supplements.” She does note a couple of exceptions. Puppies being fed a homemade diet, whether cooked or raw, may require supplements as part of the diet to ensure all necessary nutrients are provided. Eldredge advises consulting a veterinary nutritionist to be sure the diet is balanced for growth.

If your puppy is a large or giant breed, or a mixed breed that shows the potential to grow large, you may want to talk to your veterinarian about a joint supplement. These pups are more prone to developmental joint problems and may benefit from supplementation.

But one of the more common supplement recommendations – calcium – can actually lead to problems. “Excess calcium has been shown to contribute to skeletal defects in dogs,” says Eldredge. “And many minerals, such as calcium, require not only ideal amounts in the diet but also ideal ratios of other interacting minerals. Supplements may throw off a balanced diet.”

Vitamin C has recently gained popularity as a supplement. As C is a water-soluble vitamin, excess amounts should be excreted, making it relatively safe. But does it confer any advantages, or are you just wasting your money? Few studies exist to provide any answers.

Eldredge notes that many commercial pet foods now include supplements such as glucosamine and/or chondroitin for joint health, or fish oil and/or flaxseed oil for skin and haircoat. She cautions that you should check with your veterinarian before adding any supplement to your dog’s diet, including herbs, vitamins and other active ingredients.

You should also be aware that the entire area of supplements for companion animals is very loosely regulated. A testing lab found that half the supplements for pets they tested either didn’t contain the claimed amount of active ingredient or included contaminants such as lead.

John Bauer, D.V.M., Ph.D., professor of clinical nutrition at the Texas A&M College of Veterinary Medicine, recommends three areas to consider when contemplating a supplement.

Efficacy. Does the supplement provide any proven benefit? Are there scientific studies, or at least a history of veterinarian anecdotal experience?

Safety. Has the product been tested and proven safe in dogs? Note that the designation “GRAS” (generally regarded as safe) applies to use by humans, and may or may not extend to other species.

Product quality. Does the product contain the active ingredient as claimed, and no deleterious substances?

The U.S. Center for Veterinary Medicine requested a report on three specific dietary supplements for pets. But the response addressed supplements in general, noting that “clear and precise regulations” needed to be established and an active system for reporting adverse events should be set up, with public access.

A non-profit industry group, the National Animal Supplement Council, was formed in 2001 in response to the unreliable regulatory environment. The NASC initiated a Quality Seal Program.

Membership in the NASC is open to manufacturers and distributors of animal health or nutritional supplements. (An animal health supplement is a product intended to support maintenance of normal biological structure and function in companion animals, such as MSM. A nutritional or feed supplement is a product intended to provide nutritional value as a component of a complete and balanced diet, such as vitamins and minerals.)

To display the quality seal on their products, web sites and literature, NASC members must meet these criteria:

• The company must have a quality control manual with written standard operating procedures for control of the production process.
• The company must have an established procedure for adverse event reporting/complaints.
• The company must follow label guidelines for all products.
• Product labels must include any warning and caution statements recommended by the U.S. Food and Drug Administration’s Center for Veterinary Medicine and/or the NASC Scientific Advisory Committee.

In Canada, regulation of supplements was undertaken by 1998’s Interim DIN Enforcement Directive and its companion Therapeutic Products Compliance Guide. These measures are not law, but guidelines for Health Canada inspectors in dealing with supplements. As the existing law (Canada’s Food and Drugs Act) covers both humans and animals, the guidelines could potentially cover both as well. New Natural Health Products Regulations took effect January 1, 2004, but this law specifically excluded veterinary substances, so the earlier guidelines remain in effect. Bill C-51 was introduced in 2008, with sweeping changes regarding regulation of supplements, but after a storm of protest, it died when Parliament was dissolved in September that year.

Presumably, the “interim” guidelines are still in effect for veterinary supplements. Under them, a Canadian may legally import a product approved in the U.S. but not in Canada, up to a maximum of a three-month supply, for personal use.

So, the take-home message from all of this is don’t start using a supplement just because someone you know or something you read recommends it. Check with your veterinarian before adding any supplements to your dog’s feeding plan, and be aware that the quality of these products can vary widely.