Manufacturers in the $1-billion pet supplement market would like cat owners to believe that an array of their products, ranging from glucosamine to fish oil to vitamin pills, will help our cats live longer, healthier lives. Whether those supplements are actually effective is not known. Few large-scale studies have been done, and governmental oversight and regulations do not exist.
Nutritionist Joseph Wakshlag, DVM, Ph.D., ACVN, ACVSMR, at Cornell University College of Veterinary Medicine believes there is little proof that many of the promotional claims about supplements are accurate; however, one study on deep-sea fish oil has shown it can be beneficial. Dr. Wakshlag, president-elect of the American College of Veterinary Nutrition, explains more about the fish oil study in the sidebar on Page 5 and on supplements in general in the following Q & A.
Q. To help clear up any confusion, would you please provide a definition for a nutritional or food supplement?
A. It’s usually something being used to either mitigate or prevent a disease process and enhance the overall well-being of an animal.
Q. Does the government regulate them in any way for safety?
A. No, they are not regulated by either the FDA or feed control regulations, and for the manufacturer that’s the beauty of a supplement. You can put anything you want on the market, and you don’t have to do any efficacy testing. Industry-supported regulatory bodies are now out there to help ensure you are getting what the bottle says, but manufacturers often don’t put in as much of the ingredient as they probably should to have any true effects at preventing or treating a problem, just like human supplements. Concentrations are usually extremely low, so it’s hard to get appropriate pharmacological concentrations in the typical over-the-counter supplement.
Let’s say a tablet in a bottle of lycopene [an antioxidant that gives tomatoes their color] is 10 milligrams, depending on the manufacturer. A pharmacologic dose for a cat might be 30 milligrams per kilogram [2.2 pounds] to get high-serum concentrations that might be effective. So a 4-kilogram [8.8-pound] cat would need 120 milgrams or 12 tablets a day!
The manufacturer Nutramax does a lot of testing for safety, and that’s why their products are trusted by most veterinarians. They have taken a lot of toxicologic and pharmacologic steps and have shown that they deliver the proper dose and in some cases have beneficial effects.
But be cautious about using supplements. Just because your neighbor said it’s a good supplement, ask your cat’s vet first before you give it to your pet. Cats are special in veterinary medicine due to their carnivore metabolism.
Q. Why don’t manufacturers test supplements?
A. Before the Dietary Supplement Health and Education Act (DSHEA) was passed in 1984, dietary supplements — veterinary or human — were subject to the same regulatory requirements as other foods. The new law, DSHEA of 1994, says the supplement manufacturer is responsible for determining if a supplement is safe and that any claims about them are backed up by enough evidence to show the claims aren’t false or misleading. Under this law, supplements do not need to be approved by the FDA before they go on the market, nor do they have to give evidence of safety or effectiveness to the FDA unless it has a new ingredient, in which case safety data is required on the new ingredient but not anything on its effectiveness.
A lot of money is required to show beneficial effect — the amount is mind numbing — and it’s not a lucrative enough industry to do longevity studies. If you look at some of meta-analyses of glucosamine chondroitin, it appears some studies say it helps maintain cartilage. The Catch-22 in veterinary medicine is that you won’t see longevity studies. I’ve talked to some companies a bit about doing safety and longevity studies to no avail. A really good study with enough patients is going to cost a minimum of $100,000. Most companies look at the return on that, and they also wonder what happens if the study proves their product to be useless or harmful.
Q. The goal of the National Animal Supplement Council is to police the industry because there are no regulations. Do you think it’s effective?
A. It’s a good step in the right direction to get some incentive on supplements and mildly police the situation. Their members are supplement manufacturers. Strict guidelines for labeling and marketing of dietary supplements for people were created with DSHEA. This law watches the claims made by supplement manufacturers and doesn’t allow them to make claims that sound like their supplement is a drug that can cure or prevent a disease. DSHEA does not cover animal supplements, however, which is why some manufacturers grouped together to form NASC.
Q. What supplements are most commonly given to cats?
A. It depends on the disease, but the top five are liver support, kidney support, joint support and then potentially anti-oxidants and anti-cancer. Those are the ones that get the most play.
Q. Can we presume that anything that works for people works for our cats?
A. Probably not. Part of it is that if we look at simple things like antibiotic dosing, dogs and cats usually require higher doses compared to people because their metabolism and elimination rates are often higher. Animals usually metabolize medication more quickly. The same can be said for antihistamines, and in most cases steroid doses are higher in cats. The question becomes: Will supplements need to be given in higher doses, too?
Q. Do we need to talk to the vet before giving supplements to our cats?
A. Yes. I think it’s pretty important because there are certain things that can be harmful. Years ago lipoic acid was a popular antioxidant. People were giving it to their cats and some died.
Q. Is the glucosamine for people the same glucosamine for pets? If it is, can you give cats the human supplements?
A. There is not a lot of data to suggest that it’s any different, so often when I have cost-conscious clients, I will send them to the human pharmacy. For an average large dog, doses are similar as for people. You have to split pills for a cat and in many cases the dose is too small to use a human supplement.
Q. What is your take-away message for owners about giving supplements to their cat?
A. There are supplements like fish oil and glucosamine and chondroitin that likely have some modest effects that can help cats as they age so they should be considered. As we learn more about supplements and toxicities in cats, there will be more and more safe, and hopefully effective, supplements that we will be able to use for a number of maladies, keeping our feline friends happy and healthy longer into their twilight years.