Hill's Prescription Diet y/d Thyroid Care Original Flavor Dry Cat Food, 8.5-lb bag

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About This Item

Details

  • See results in as little as three weeks when fed as the sole source of nutrition.
  • Thyroid Care works to decrease T4 hormone production while supporting your cat's kidney, heart and urinary health.
  • Helps support lean muscles and a strong immune system while also promoting a visible improvement in skin and coat.
  • Formulated with S+OXSHIELD to help reduce the risk of developing struvite and calcium oxalate crystals in urine.
  • Contains limited iodine, controlled phosphorus and reduced sodium levels.

Ingredient Information

Feeding Instructions

FAQ

Learn More About Hill's Prescription Diet From Our Team of Experts

Hill's Prescription Diet y/d Thyroid Care for Cats

Groundbreaking Nutrition for Thyroid Health

Hill's breakthrough formula was designed to help felines with hyperthyroidism thrive. Cats with this disorder have an overactive thyroid gland—meaning it produces too much of the thyroid hormone—but limiting iodine in your cat's food can help regulate it. Prescription Diet y/d does that and more, all in a tasty kibble your cat will love. You may even see a difference in as little as three weeks.

Clinical Nutrition

With Hill's, it's not just high-quality ingredients that count. Their focus is on the proper balance of nutrients in every recipe. So, Hill's designed food to help pets with health conditions, providing the right nutrients to support their health. Hill's alliance with veterinarians puts them in a position to find a nutrition recommendation for your pet, no matter what health issue your pet is facing.

Formulated by Veterinarians

Hill's Prescription Diet started with a veterinarian's belief that some health issues could be managed through nutrition. What began as a theory has now been proven through extensive research by a team of over 220 vets, PhD nutritionists and food scientists. The results can be seen in Hill's Prescription Diet therapeutic pet foods.

Meeting the Highest Standards

Providing a food that delivers exactly what it says it does is Hill's number one priority. In fact, they perform over five million safety and quality checks every year. They've established relationships with trusted suppliers and will only accept ingredients that meet stringent standards.

The Taste Factor

You might know that Hill's Prescription Diet is good for your pet, but she's only concerned with the taste. Even though they place a heavy emphasis on nutrition, Hill's hasn't forgotten about palatability. Savory ingredients are combined to produce foods with enticing aromas, textures, and shapes that your pet can't resist.

How Hill's y/d Helps Manage Thyroid Health

Key Nutrients

  • Limited Iodine
  • High in omega-3 fatty acids
  • Controlled phosphorus and low sodium

Health Benefits

  • Decreased T4 production
  • Supports kidney, heart and urinary health
  • Promotes skin and coat health

About Hill's Prescription Diet

Hill's mission is to help enrich and lengthen the special relationships between people and their pet. Their Prescription Diet product line delivers clinically proven nutrition that supports common pet health concerns, from digestive and urinary health to aging and weight management.

Shop Hill's Prescription Diet

Questions & Answers

20 Customer Questions


I have 2 cats and only has a hyperthyroid. The vet meds have made him so sick that I wanted to try an alternative. Will this food be harmful if eaten by my cat who doesn't have hyperthyroidism but has asthma? They share a dry food bowl and feeding them independently would be a challenge. Thank you.

Answer by ChewyNov 15, 2018
Since this is a prescription food formulated to meet specific diet restrictions from known health issues, this food should not be fed to any other animal than the one prescribed due to the restriction of specific nutrients. Prescription diets can be detrimental to an otherwise healthy pet if that pet doesn't have the ailment for which the food is designed.

Is this food for an over-active or under-active thyroid problem (i.e. hyper- or hypo-thyroidism)?

Answer by ChewyApr 23, 2018
This formula is not designed for over-active or under-active thyroids specifically, instead it helps to promote the overall health of the thyroid. It contains limited iodine to decrease T4 hormone production. This product also supports kidney, heart and urinary health with controlled phosphorus, low sodium, and a desirable urine pH.

Is it safe to feed this to a hyperthyroid cat does take methimazole, but not always the full dose? She is also in very early renal failure. Are the phosphorus & sodium levels low enough to be beneficial?

Answer by ChewyNov 20, 2019
Due to your feline's underlying medical condition, we suggest speaking to your veterinarian to determine if this is the best option for your cat.

Does the 8.5 lb bag not have the S+OXSHIELD? when I hover over the 8.5 lb option, the S+OX logo disappears from the photo of the bag.

Answer by ChewySep 11, 2018
Both the 4 and 8 1/2 pound bags are formulated with the S+OXSHIELD to meet specific nutrient standards, shown to promote a urinary environment that helps reduce the risk for struvite and calcium oxalate crystals.

4.5
Rated 4.5 out of 5 stars
1357 Ratings

Customers Mention

Chewy identifies key considerations with the help of artificial intelligence and our veterinarians.

Digestibility

79% Positive

Ingredient Quality

80% Positive

Nutritional Content

78% Positive

Palatability

77% Positive

742 Customer Reviews



Always consult a veterinarian about your pet’s health needs. Customer reviews should not be used as medical advice.

Rated 5 out of 5 stars
By Vicki on Jan 26, 2026

Y/d

Zeus loved this while he was able to be on his diet for thyroid care. He now requires medication and cannot eat this formula while taking the medication. Early

Zeus loved this while he was able to be on his diet for thyroid care. He now requires medication and cannot eat this formula while taking the medication. Early in thyroid care diagnoses, this food is great. But thyroid care does advance over time, no matter what food the cat eats. Quality veterinary care is a requirement as this food is only available by prescription.


Rated 1 out of 5 stars
By Tami on Jan 12, 2026

Not sure

Our cat didn't seem to do too well on this dry food that was recommended by her doctor for her diagnosis of hyperthyroidism, but that might not be the same for all

Our cat didn't seem to do too well on this dry food that was recommended by her doctor for her diagnosis of hyperthyroidism, but that might not be the same for all cats. She would eat it and throw it up. Unfortunately she just passed away on Friday so we didn't have her on this food long enough to see if that resolved itself or not.


Rated 5 out of 5 stars
By Judy on Jan 2, 2026

Gypsy Seems to Live It

Gypsy is now 100% on the y/d dry cat food. She's also on the y/d canned but her go to is the dry. It's perfect for late night snacks when I'm not awake to prepare

Gypsy is now 100% on the y/d dry cat food. She's also on the y/d canned but her go to is the dry. It's perfect for late night snacks when I'm not awake to prepare a little wet meal for her so I feel good that she stays on this life-saving food even when I'm not there to make sure she's staying on track.


Rated 2 out of 5 stars
By Natalie on Dec 17, 2025

Cat didn't like it at all

Sadly, our cat wouldn't eat the dry nor wet food. I tried everything I could think of but he wouldn't go for it :(. I must say they were good size cans since

Sadly, our cat wouldn't eat the dry nor wet food. I tried everything I could think of but he wouldn't go for it :(. I must say they were good size cans since they were more then the food we were buying.


Rated 4 out of 5 stars
By Nancy on Dec 3, 2025

Best service ever!

My car has a thyroid condition and there isn’t a food I can substitute this condition with. The vet had run out of this food and it was going to take a week to

My car has a thyroid condition and there isn’t a food I can substitute this condition with. The vet had run out of this food and it was going to take a week to for them to restock it. Chewy was able to deliver this to me in one day.


Rated 4 out of 5 stars
By Gail on Oct 9, 2025

Give your kitty time to adjust to the prescription diet

I have had numerous animals on prescription diet foods and not one has ever liked it. Give your pet, dog or cat, several days. When they get hungry enough they will

I have had numerous animals on prescription diet foods and not one has ever liked it. Give your pet, dog or cat, several days. When they get hungry enough they will do more than pick at it. It took 3 days for the kitty to really eat the food, but after several months, there is a definite improvement in the cat. She has gained some weight and doesn’t eat near as much food as she did. Hyperactive thyroid kitties have voracious appetites, but continue to loose weight even though they eat twice what a normal kitty does.


Rated 3 out of 5 stars
By Tracy on Nov 13, 2025

Science Diet Y/D Thyroid

My kitty had a reaction to thyroid medication so this food provided an option for treating his hyperthyroidism. I'm thankful Science Diet makes this food available

My kitty had a reaction to thyroid medication so this food provided an option for treating his hyperthyroidism. I'm thankful Science Diet makes this food available because there aren't any other options. He doesn't much care for the dry kibble but does like the wet.


Rated 3 out of 5 stars
By Ana on Nov 5, 2025

Dry food for tyroid

He prefers dry food than the wet type for this special diet, but it is not his favor, he will go around begging for something else before he realized that nothing

He prefers dry food than the wet type for this special diet, but it is not his favor, he will go around begging for something else before he realized that nothing else is coming... i often wonder why all this specialty diet foods seem to be so blend and animals never seem to be so eager to eat it.


Rated 1 out of 5 stars
By Jane on Dec 13, 2025

Fed Ex did not deliver the product

We were home all day and the delivery was not made to our house. We have a ticket filed with Fed ex but we will need the food for Domino soon as his food is almost

We were home all day and the delivery was not made to our house. We have a ticket filed with Fed ex but we will need the food for Domino soon as his food is almost gone.


Rated 5 out of 5 stars
By Susan on Dec 19, 2025

Quality of food

Sasha LOVES this kibble. This is ESPECIALLY important, because she is limited to the Hills Thyroid Y/D dry (& canned), and she loves the Hill's Y/D kibble!

Sasha LOVES this kibble. This is ESPECIALLY important, because she is limited to the Hills Thyroid Y/D dry (& canned), and she loves the Hill's Y/D kibble!