The word is out: Nutrition is a new option for managing cats with hyperthyroidism. Limiting dietary iodine induces euthyroidism in cats that have naturally occurring hyperthyroidism, according to studies by Hill’s Pet Nutrition Inc. of Topeka, Kan. Hill’s determined that if the iodine content can be kept below 0.32 ppm, hyperthyroidism in cats can be controlled through nutritional therapy alone. Hill’s released its Prescription Diet y/d Feline Thyroid Health in dry and wet formulations in October. Hill’s describes the food as a daily, low-iodine nutrition solution designed to manage hyperthyroidism in cats, and says it is clinically proven to improve thyroid health in three weeks. The next step is incorporating this new option into the veterinary practice. First Things First: Diagnosis “Fortunately, diagnosing [feline] hyperthyroidism is pretty easy,” said David Bruyette, DVM, Dipl. ACVIM, medical director at VCA West Los Angeles Animal Hospital. Hill’s invited Dr. Bruyette to use the pet food with some of his patients before the new product’s launch. “Most veterinarians now are screening older cats by measuring T4, the major thyroid hormone,” he said. “The vast majority of cats—about 93+ percent—that are hyperthyroid will have a high total T4, in which case the diagnosis is very simple.” A small subset of cats will have a T4 in the upper half of the reference range, Bruyette said. In those cases, additional testing would be indicated, such as measuring the free T4. If that’s elevated, then a veterinarian could conclude that the cat has hyperthyroidism, he said. Hill’s has created a diagnostic flow chart outlining this very concept. The chart outlines the clinical findings (i.e., weight loss, polyphagia, hyperactivity, tachycardia, vomiting, diarrhea, etc.) and initial evaluation (i.e., physical examination, complete blood count, serum thyroxine, etc.) and then breaks down how to proceed based on the T4 results. Therapeutic Options After diagnosis, the next step is talking to the pet owner about all management options, said Chad Dodd, DVM, of the global marketing and innovation team at Hill’s Pet Nutrition. Therapeutic options include thyroidectomy, radioactive iodine, antithyroid medications and now nutritional management. “We have to have a dialogue with our client to see which one of these options is going to work best for the cat and cat owner,” he said. Each option has pluses and minuses, Dr. Dodd added. For instance, some pet owners may not be able to pill their cat daily while others may have financial constraints and be unable to pay for an options such as radioactive iodine therapy. The nutrition route may not be suited for all hyperthyroid cats, Dodd and Bruyette noted. If a cat is on a different therapeutic food for another condition, Prescription Diet y/d Feline may not be the best option, they said. Still, Bruyette’s goal is to manage hyperthyroid cats first with pet food alone, as long as there is no reason the cat can’t be on the food. If the food is not successful, the next step is to go back and talk to the owner about medications, surgery or radioactive iodine, he said. Veterinarians need to be forthright and make sure the client is informed, Dodd said. “The introduction of a new food is going to allow us to have an even broader discussion with the client and potentially give them something that’s going to be a little bit easier,” he said. Most cats transition to the food over seven days, although some may need longer. The cat should be rechecked four and eight weeks after the transition is complete, Hill’s advises. Serum T4 should be decreased at first recheck and within reference range in most cats by eight weeks, according to the company. Rechecks should be conducted every six months indefinitely. Results are dependent on pet owner compliance in feeding the cat only y/d Feline. No outside iodine-rich dietary products are allowed. When making recommendations for a multi-cat household, it’s especially important to emphasize that the hyperthyroid cat should consume only y/d. Bruyette indicated that Hill’s has fed limited-iodine foods to healthy adult cats for one year and hyperthyroid cats for up to five years with no observed side effects. Cats with normal thyroid function living in the same household can eat Prescription Diet y/d Feline as a daily pet food if they cannot be easily separated for feeding; however, it’s recommended that their meals be supplemented with 1 tablespoon of regular cat food (dry or canned) each day to provide additional iodine. Because y/d Feline is formulated for senior cats and contains limited iodine, it should not be fed to kittens or cats that are pregnant or lactating. Since Prescription Diet y/d Feline Thyroid Health is just hitting veterinary clinic shelves, most cats with hyperthyroidism are probably currently on some other treatment, the most popular, according to Dodd, being antithyroid medications. With that in mind, Hill’s has created a set of recommendations for transitioning a cat from antithyroid medications to y/d Feline: * Conduct a physical examination, CBC, serum chemistries, urinalysis and T4. * Transition to y/d Feline and immediately decrease daily medication dose by 50 percent. * Discontinue medication when cat has been eating y/d Feline exclusively for one to two weeks. * Initial rechecks—physical examination, T4, BUN, serum creatinine and urine specific gravity. * Long-term rechecks—physical examination, T4, CBC, serum chemistries and urinalysis. The company notes that these are general guidelines only; “Use clinical judgment to make decisions for individual patients.” Team Effort Getting the staff involved, as with any condition, is very important, Dodd said. “The role of the technician is not only to be able help answer questions but to take visual cues,” he said. Often, as soon as the vet walks out the door, the client has follow-up questions. The veterinary technician is a great resource to answer such questions and provide clarification, Dodd said. Veterinary technicians can also follow up with clients by calling them to see how things are going, he added. Because pet owners pick up medications at the front desk, it’s also a great opportunity for staff to talk to owners about the possibility of switching to nutrition as a hyperthyroidism management option, Bruyette said. The owner would then have a follow-up discussion with the veterinarian. Renee Pearson, RVT, specialty technician supervisor at VCA Los Angeles and assistant to Bruyette, said her role as a veterinary technician includes helping the client understand how this management option works and answering any client questions. The healthcare team plays a huge role in a management program, Pearson noted. A bond is created among the veterinarian, the veterinary technician and the owner and pet, she said. In addition, clear communication between veterinarians and technicians builds overall trust in not only the team but in the hospital in general, she said. “Our clients really pick up on that,” Pearson said. “They see our camaraderie and it makes them feel good about what we are asking them to do. … It’s important that clients not just believe what you are saying because the science is there but that they believe what you are saying because you are really interested in helping the client and their pet have a much more enjoyable lifetime together.” Dodd said practices can request educational materials from their Hill’s representatives or by calling the Hill’s Veterinary Consultation Service at 800-548-8387. Having nutrition as a feline hyperthyroidism management option is creating discussion and getting the academic and general practitioner communities all thinking about cats, Dodd said. “We have identified something that we didn’t know before, and it’s going to help us practice better medicine, be better veterinarians and be better pet owners,” he said. This Education Series article was underwritten by Hill’s Pet Nutrition of Topeka, Kan.
