Last week, the FDA released a draft compliance policy guide, a document that reflects their current thinking on this topic of therapeutic pet food diets. It directs FDA staff and industry on how the agency intends to use its enforcement discretion. At issue is the leeway that allows these therapeutic diets to be regulated as "food," even though many FDA officials believe these diets really act as "drugs" because of their intended effects.
Therefore, FDA intends to specifically address dog and cat food products that are labeled and/or marketed as a means to diagnose, cure, mitigate, treat, or prevent diseases. They are especially interested in looking at diets that are marketed as an alternative to approved animal drugs and those that make a specific disease claim.
For more information about this topic, see the link to the article published by the VIN News Service (1), as well as the FDA web site to read the draft compliance policy guide on this topic (2,3).
Hill's y/d Diet and the FDA
The FDA's draft compliance policy guide almost seems like an direct response to my past criticism about how the Hill's y/d diet has been marketed in this country. For over a year now, Hill's Pet Foods has heavily been promoting y/d as a first-line treatment for a disease (i.e, feline hyperthyroidism). According to the company marketing ads (see below), Hill's y/d diet is promised to "improves thyroid health in 3 weeks" and is "clinically proven to restore thyroid heath" when fed to cats with hyperthyroidism.
Based on their vigorous marketing program, the Hill's pet food company is highly recommending this diet as a hyperthyroid treatment, meant to replace the other time-proven therapies. They even provide guidelines for how to weaning the cats off of methimazole and transition them on to the y/d diet.
In other words, Hill's is marketing y/d more like a drug to treat hyperthyroid cats than a diet per se. Unfortunately for the practicing veterinarian, the company has not done the Phase II or III drug trials normally required to determine a "drug's" efficacy or safety. Remember that all of the current data we have on this diet is based on only about 150 cats or so, most of which were colony cats at the Hill's Pet Nutrition Center. We still need more real data, and all we have now are a few abstracts that were published over a year ago (6-7).
Because Hill's says that y/d is not a drug (although it's certainly being marketed as one), the company is not required to do any long-term safety studies, and it's fairly clear that they have no intention of paying to have them done. Maybe the FDA can change some of that, or at least make Hill's modify and deflate their marketing claims.
- VIN News Service. FDA poised to tighten oversight of therapeutic pet foods. September 14, 2012.
- FDA web site. Inspections, Compliance, Enforcement, and Criminal Investigations. Manual of Compliance Policy Guides.
- FDA web site. Draft Compliance Policy Guide: Labeling and marketing of nutritional products intended for use to diagnose, cure, mitigate, treat, or prevent diseases in dogs and cats.
- Hill's Pet Nutrition website. Prescription Diet y/d Feline Thyroid Health.
- Melendez LM, Yamka RM, Forrester SD et al. Titration of dietary iodine for reducing serum thyroxine concentrations in newly diagnosed hyperthyroid cats [abstract], J Vet Intern Med 2011;25:683.
- Melendez LM, Yamka RM, Burris PA.Titration of dietary iodine for maintaining serum thyroxine concentrations in hyperthyroid cats [abstract], J Vet Intern Med 2011;25:683.
- Yu S, Wedekind KJ, Burris PA, et al. Controlled level of dietary iodine normalizes serum total thyroxine in cats with naturally occurring hyperthyroidism [abstract], J Vet Intern Med 2011;25:683-684.