Saturday, September 15, 2012

FDA Addresses the Issue of Therapeutic Pet Foods

The U.S. Food and Drug Administration (FDA) is scrutinizing pet foods with labels claiming to treat or mitigate disease, suggesting that the sale of some brands call for a veterinary directive much like that of prescription medications.

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.

  1. VIN News Service. FDA poised to tighten oversight of therapeutic pet foods. September 14, 2012. 
  2. FDA web site. Inspections, Compliance, Enforcement, and Criminal Investigations. Manual of Compliance Policy Guides.
  3. 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
  4. Hill's Pet Nutrition website. Prescription Diet y/d Feline Thyroid Health
  5. 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.
  6. 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.
  7. 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.


The Indulged Furries said...

I'm just a pet owner, not a vet, but I've often been frustrated with Hill's foods and their marketing methods.

Years ago I had a cat who was both diabetic and hyperthyroid. At the time (1997), Hill's w/d was commonly given to diabetic cats, and we fed it to our cat. But it was becoming clear that that higher protein, low carbohydrate diets are better for diabetics. Fifteen years later, Hill's still markets w/d. Maybe it's appropriate for some cats, but I'm not sure what case that would be.

We managed our cat's thyroid levels with methimazole. After reading all your posts about y/d, I printed many of them and gave them to my neighbor whose cat was recently diagnosed hyperthyroid and put on y/d. She discussed it with her vet and has stopped y/d and has the cat stabilized on oral thyroid medications.

Hill's is extremely effective at marketing their mediocre foods. I know our local shelters feed Hill's food because they get it for the cost of shipping. When I attended U.C. Davis, vet students got Hill's food for free.

I want to thank you for having the expertise and fortitude to make this information available to the public. Information that you provide helps owners educate themselves that well marketed foods may not be the best choice for their pets. Other vets are not as willing to go up against the Hill's juggernaut.

Anonymous said...

thank you for this blog. my cat has just been diagnosed with thyroid problems, and is geriatric, and I thought this food would be the best alternative. The cat hates which should tell you a lot. I am going to try the medicine and see if she tolerates it. What do you think about the iodine therapy treatment?

Dr. Mark E. Peterson said...

Depending on your cats overall medical condition and age, radioiodine is generally considered the treatment of choice. Talk to your vet about their thoughts with your cat.

Cathy Caruso said...

Hello Dr. Peterson. Please help me. My male cat is 16. He has hyperthyroidism. He was given methimazole for 6 months in increasingly larger doses but it made no difference at all in his level which was >129. His Vet recommended Hills YD. He ate it (only it) in canned form and then suddenly stopped eating altogether. Prior to beginning this new food, he was eating normally. We took him off the food entirely. He had to be given fluids subcutaneously because he became so dehydrated. Once we came home from the Vet, he was ravenous and ate like a pig. Rather than changing his food completely like I'd done the first time with the YD, I tried gradually to reintroduce it beginning with 3/4 Nirmal food to 1/4 YD. Again, he stopped eating altogether. Today I brought him in again because he stopped eating and he was given fluids again. Since we've been home, he ate and drank. The Vet told me we're "losing the battle" and that giving him fluids now to get him to eat is our only option. Because I believe the YD is the culprit, I'm not sure what to think. Your insight would be greatly appreciated. I'm heartbroken at the thought of having to euthanize him and my gut is telling me that the high protein diet is what he needs. Am I dreaming in technicolor or am I on to something?

Dr. Mark E. Peterson said...

Why would you have to euthanize a hyperthyroid cat? If methimazole or y/d aren't working, then treat with either thyroidectomy or radioiodine. Both better treatments anyway.

Kewpie said...

Hello Dr Mark,
Interesting reading, I'm researching the best way to feed my hyperthyroid 12 yr old cat who seems to also be sensitive to a lot of the mass produced kibble out there, and has lots of fur balls. She reacted badly to methimazole, vomiting, swollen lips, scratching and had to be hospitalised and given IV fluids for 28hrs. She vomited everyday for almost a week after coming home, and is just settling, I think the drug is out of her system now. It worked for the two weeks she was given it with her levels dropping to normal range. However, I am not going back to the drug, after lots of chats to my vet, other vets and research, I am going to outlay the costs for radio iodine. It seems the best option for her. But she won't be having it done for four weeks and I worry about how to best manage and feed her in the interim. I wondered if I should feed her on this y/d. But now I don't think so. The clinic she's going to be treated at has been wonderful and sympathetic with my concerns about putting her back on the methimazole prior to treatment. Do you have any suggestions as to what best to feed her over the coming weeks to maintain her health? I've read that kibble really isn't great, and I need to be wary of high carb fillers. Is raw or lightly cooked human meat ok? I've become very well read about hypothyroidism over the last few weeks! Will look at more of your articles.

Dr. Mark E. Peterson said...

I agree with your decision to go ahead with radioiodine treatment. Whatever diet you choose, you want one that is balanced for cats, so cooking meat isn't going to do that unless you work with a nutritionist. Check out Lisa Pierson's website ( for more information about what to feed.

Kewpie said...

Thank you for your information, I've had a good read of that site both before and after I received your reply. Your information is very helpful.