The team at VCA West Los Angeles Animal Hospital was puzzled.
Veterinarians had recently begun managing feline hyperthyroidism with nutrition, using a pet food formally launched in October 2011, Hill’s Prescription Diet y/d Feline Thyroid Health. The food limits dietary iodine intake, and the staff was finding that in the majority of cats, thyroid levels returned to normal within three weeks of transitioning to the food.
But one patient’s thyroid levels had barely budged—even though the owner insisted the cat had been fed only the recommended food.
So team members started probing, says David Bruyette, DVM, Dipl. ACVIM, medical director at the hospital. Was the cat getting treats? Never. Did it sneak bites from other food bowls? Not that the owner knew.
Finally, a new fact emerged: The owner had been out of town for 10 days. And it turned out that when the affected cat’s food bowl ran empty, the owner’s husband had simply re-filled it with the same food that the other cats in the household ate, Bruyette says.
“This food is so good at limiting iodine that if the (cat’s condition) is not improving, there’s an incredibly high chance that the cat is getting food somewhere else—even if the owner insists otherwise,” Bruyette says.
So, thorough client education—and when necessary, follow-up detective work—is a critical component for any veterinary team using nutritional management for hyperthyroid cats, Bruyette says.
A Common Ailment
Hyperthyroidism in cats is common; about 10 percent of cats over 10 years of age, and about 3 percent of all cats, develop it, says Lynda Melendez, DVM, MS, Dipl. ACVIM, medical director of clinical research at Hill’s Pet Nutrition of Topeka, Kan.
If left untreated, hyperthyroidism can lead to more serious conditions like kidney or heart failure, or even death.
But traditional treatments—radioactive iodine, thyroidectomy or antithyroid drugs—are considered invasive, expensive or inconvenient by many owners, Bruyette says. He has added Hill’s y/d Thyroid Health to the treatment protocol at his practice and says owners have tended to react favorably when informed of the new option.
“Some owners seem to feel it’s a more natural option. Some don’t like the idea of surgery or having to pill a cat every day. And some see it in economic terms—if we can control and manage this disease with nutrition, the overall medical costs are reduced,” Bruyette says. “The owner has to buy food anyway. So even though this is a lifetime management, and the cat will have to eat this food for the rest of its life, owners may see this as a more affordable option.”
Hill’s spent 10 years developing the product based on a theory that if dietary iodine were limited, normalized thyroid levels would result. After years of work, researchers determined that an iodine content of = 0.3 ppm was optimal; it would sufficiently limit iodine intake but would not create iodine deficiency, Bruyette says.
Because iodine content in other foods can vary widely, from 1.5 ppm to 99 ppm, and because iodine content is not typically disclosed on pet food packaging, it would be difficult or impossible for owners to control iodine intake on their own, he adds.
Clinical trials by Hill’s indicated that 90 percent of hyperthyroid cats are returned to a euthyroid state through nutritional management, Melendez says. This is just slightly below the success rates of traditional treatments of radioactive iodine (94 percent) and thyroidectomy (92 percent), and better than anti-thyroid drugs (82 percent), says Bruyette.
To replicate those results in the real world, veterinary teams must do a good job of initial education and provide thorough follow-up, says Kara Burns, MS, MEd, LVT, technician specialist at Hill’s.
Initially, Burns says, the team should recommend a gradual transition to the hyperthyroid food from the cat’s previous food; Prescription Diet y/d is available in both wet and dry formulations to ease the transition.
Next, the technician should follow up within three days to answer any questions, make sure the owner is following recommendations for feeding amounts and restrictions, and offer advice and guidance, especially if the cat has been weaned off thyroid medication or has any other medical conditions.
“Technicians should ask the owner, how is the transition to the new food going?” Burns says. “Does the cat seem to be adjusting to the new food?
“When the cat is transitioned to y/d, the technician needs to probe to ensure that the cat is getting only the new food,” Burns adds. “Make sure the cat is not gaining access to any other foods, treats, or liquids, other than water. Does the cat go outside? If so, is there a chance that the cat is getting food at a neighbor’s house?”
The team can also use this follow-up phone call to remind the owner to keep follow-up appointments. Follow-ups are recommended initially every four weeks, until the cat’s T4 has returned to normal, and then every six months afterward, Burns says. Cats that have concurrent conditions such as kidney or heart disease should be monitored more often (every one to two weeks) until they are stable.
If the first follow-up reveals that the cat has not responded as expected, more questions are in order. For instance, the team may want to inquire about visitors to the household and make sure every member of the family is on board with nutritional management.
One technician, for instance, discovered through a follow-up that a client was giving her cat a dental chew daily, Burns says. The iodine level in that chew was high enough to keep the cat’s T4 level elevated.
“Owners may not realize that some of the little things they do, like letting the cat lick the last bit of yogurt off the spoon, can really make a difference,” Melendez says. “To them, that’s not feeding; that’s just a little treat, and they don’t recognize the role that it can play in their cat’s overall health.
“Because this is such a new way to manage this condition,” Melendez adds, “veterinary teams really need to be involved in working closely with owners, to monitor the cat’s health and make sure the owners are being compliant with the recommended treatment.”
This Education Series story was underwritten by Hill’s Pet Nutrition of Topeka, Kan.