Volumes have been written about the dietary supplement business, which is a multibillion dollar industry with†powerful political connections and terribly inadequate regulations that allow widespread marketing of supplements without a solid basis in science or scientific evidence.†The veterinary supplement market is small compared to the human market, but it is still huge. The lionís share of the pet supplement market goes to a few specific compounds. There are also serious problems with quality control of the largely unregulated veterinary supplement industry. There are also many products marketed with ridiculous and completely unsupported claims.†Most of these ingredients are also among the most popular supplements for humans.†Letís look at a few popular ones here.GlucosamineThe biggest name in the veterinary supplement world by a large margin is glucosamine. It is believed by pet owners and many veterinarians to be an effective treatment for osteoarthritis.†It is sold alone or in combination with chondroitin, MSM and many other ingredients. It is sold over the counter and through veterinarians, and as an additive in commercial pet foods.Bottom-line is this: Decades of clinical trials have failed to find any consistent benefit, and what evidence you may find shows it is no better than a sugar pill in treating arthritis in humans. It is a shame that so much of this is touted for use in our dogs and cats, but there is almost no clinical research on glucosamine as a treatment for arthritis.ProbioticsThese are ìbeneficialî bacteria we place in the gastrointestinal track to help balance the flora of bacteria and hopefully help various conditions. There is some evidence in benefiting people with antibiotic-associated diarrhea, but many of the claims made for health maintenance or ìboosting the immune systemî are unsupported.There is less research on probiotics for dogs and cats, but there are some encouraging studies, which show a likely benefit of some products. The idea of probiotics as a therapy for gastrointestinal disease seems promising, but this optimism must be tempered by the very limited understanding we have of how these work in the gastro-intestinal track and the concerns about poor quality control and exaggerated, unscientific claims made by the companies that sell them.MultivitaminsMultivitamins are widely touted as a preventive health measure or as ìinsuranceî for a nutritionally imperfect diet. Expert biochemists increasingly say that taking a multivitamin is more a form of ìself-administered psychotherapyî than a preventive health practice.†A 2006 detailed review of the available evidence does not support claims of health benefits in humans from vitamin supplementation in the absence of confirmed deficiencies. And there are circumstances in which vitamin supplementation can be harmful (for example,†raising cancer risk,†interfering with cancer therapy, or even increasing mortality).†As usual, there is virtually no research on the subject in dogs and cats. Commercial pet diets are nutritionally balanced, unlike our human diets, so there is even less reason to think a multivitamin would be necessary in dogs and cats. In fact, such supplementation could very well lead to excessive, even toxic levels of fat soluble vitamins or some minerals.Homemade and†raw food pet diets, however, are more likely to be nutritionally inadequate, so multivitamin supplementation might be more appropriate when feeding such diets.Digestive enzymesThe†claims made for digestive enzyme supplements†are often sweeping and dramatic, and they can make you wonder how anyone ever digests their food without them.Healthy humans and dogs have all the enzymes they need to effectively digest foods. The organs that produce such enzymes do not become stressed or fatigued by doing what is, after all, their normal function. So no surprise to you now, there is no clinical research at all on the subject in cats and dogs.Fish oilAfter glucosamine, one of the most popular supplements for pets is fish oil. In humans, the most common use of this supplement is for the prevention of cardiovascular disease. In general, this is a supplement where there is good evidence for some benefit in cardiovascular disease prevention and other benefits.As our cats and dogs donít have atherosclerosis, this supplement is most commonly used in the treatment of skin allergies. For treating canine skin allergies, there is good evidence that fish oil supplements can improve coat quality and reduce the dosage of steroid medications needed to control itching.The other common use of fish oils in pets is for treatment of arthritis. There have been several studies of fish oil as a therapy for osteoarthritis in dogs. The company that has done the most research is Nordic Naturals (Omega Pet for dogs and cats); and, as it turns out, they are the ones with the highest medical grade in the fish oil and they have both human and pet products that many people swear by.Bottom lineThe marketing used to promote these supplements goes well beyond anything justified by real scientific evidence, and is almost universally untrustworthy. Likewise, the testimonials and anecdotes about their effects, whether from patients, pet owners, veterinarians are all just stories with almost no real medical value. So, before using all your money that could be used on known treatments, I would caution you to wait on most supplements because the evidence, or lack thereof, is, frankly, embarrassing.Dr. Jim Humphries is a veterinarian and also serves as a visiting Professor at the College of Veterinary Medicine at Texas A&M University. He provides hospice and end of life care for pets. He lives in Falcon with his wife, horses and Great Danes. www.MobilePetDocs.com
