Feline Hyperthyroidism: The Alarming Facts - Groomer to Groomer Magazine
Feline Hyperthyroidism: The Alarming Facts

Feline Hyperthyroidism: The Alarming Facts

By Deborah Hansen

I will be the first to admit that I thought my clients were being neurotic or the vets in my area were over diagnosing hyperthyroidism. Almost every cat I groom seems to have a  hyperthyroidism diagnosis.

When I began researching hyperthyroidism, I was shocked to learn that it is a valid disease and seems to be a result of the environment. Research shows that a substance developed to keep humans safe is actually harming our feline companions.

What Are The Facts?

The first cases of Feline Hyperthyroidism (FHT) were written about in 1979. In the early 1980s, FHT was treated by a specialist. Unfortunately, FHT is so common that today general practitioners treat FHT. It is estimated that over 10% of household cats over the age of 10 have FHT. In my grooming business, I am noticing a trend of younger cats developing the disease. Research supports that in the 1980’s FHT was a new disease, as compared to an undiagnosed disease. The questions then became why and how are household cats getting FHT? We know FHT is a house cat disease, as feral colonies are not presenting FHT when blood samples are taken.

It is suspected and research is supporting that the chemical polybrominated diphenyl ethers (PBDE) that is added to household furnishings, electronics and vehicles to prevent fires is the cause of the elevated occurrence of FHT. We are led to this belief for several reasons. FHT was unheard of in the 50’s and 60’s before PBDE was commonly used. As PBDE became the standard fire retardant used in consumer products the occurrence of FHT started showing up in cats. The FHT cases increased as the use of PBDE increased.

The problem comes because PBDE does not form a chemical bond to the surfaces it is applied. This lack of bonding allows the chemical to easily “flake off”. The results are a twofold dilemma for our feline friends. First, when the chemical “flakes off” it floats around our home environments as dust particles. The dust particles either land on the coat or are stuck to the coat through normal feline activities such as lying under the TV, racing across furniture, rolling on the carpet, etc. When the felines lick their coats, PBDE is ingested. A home with FHT cats has PBDE levels up to 180 times a home without FHT cats.


Second, cats are exposed to the fire retardant chemical when they are kneading or scratching. Before 2004, PBDE was commonly applied to carpets, upholstery, bedding, and curtains. All the places cats love to mark or readjust with their claws had the chemical that literally was just sitting on the fibers of their favorite places. When a cat makes a new cozy spot to lie, scratches the carpet or races behind curtains, PBDE is released and settles into the feline coat. Later the feline will lick the PBDE off and it will build up in its body.

To make matters worse, PBDE is now also found in fish flavored cat food! Come to find out PBDE is naturally occurring in marine animals. We already know that predatory fish at the top of the food chain contain high levels of toxins such as mercury and pesticides. They also contain high levels of PBDE. Tilefish is the fish in cat food labeled as “ocean whitefish.” Tilefish, along with king mackerel, shark and swordfish are currently the most contaminated fish in our oceans.

What Are The Symptoms Of FHT?

The physical symptoms include weight loss—despite a normal or increased appetite, increased urination, increased drinking, not using the litter box, increased vocalization, restlessness, vomiting, diarrhea and poor coat. The official diagnosis of FHT comes from a blood test indicating an elevated thyroid hormone concentration (T4 or T4 plus FT4ED) with one or more of the physical signs. While grooming these cats, I have noticed they tend to lick their lips excessively. 

How Is FHT Treated?

My grooming clients seem to choose one of three treatment options, however, there are currently four options listed by the AAFP.

First, and the least invasive treatment, is diet. About half my current grooming clients have had success with this method. Studies show that more than 81% of patients have success with this method. The problem comes if the cat is taken off the diet, given treats or has access to another food source.

Most common for my clients is transdermal medications, however, it can also be administered orally. As with any medications, it does have side effects and not all cats are “easy” for owners to medicate. The guidelines call for the medication to be administered once or twice a day.

A third method is radioactive iodine. Many of my clients opt for this treatment. Studies show it cures over 95% of the cases of FHT, with a 5% relapse rate. There is a hospitalization period of 3+ days where the owner is not permitted to visit the cat due to radiation levels. Then the cat’s waste needs to be collected and the owner cannot cuddle for 2 weeks after discharge.  

An option my clients do not seem to use is surgical thyroidectomy.

Interestingly enough, the current projections show that over the lifetime of the feline, it does not matter if the owner selects diet, medication or radioactive iodine, the costs of the treatment seem to be equal at this point in time. The only difference is if the client chooses to endure the costs upfront (radioactive iodine) or over the life of the feline (diet and medication).

What Does This Mean For Groomers?

My business will not groom a radiation iodine treated cat for a month after treatment, and then only with vet approval. The studies show that the radiation leaves the body through waste within two to four weeks of treatment. My business is based on lap grooming, which leads me to have two concerns regarding a feline immediately following radioactive iodine treatment. First, potential radiation lying over my reproductive organs for up to two hours. Second, having the felines’ waste on my body which may still contain residual radiation. If transdermal medication is given in the ear, I do not clean the ears.

My business model does not provide any kind of treats or food to the cats we groom. If your business does, a cat being treated by diet should only have vet approved items.

In conclusion, felines with FHT can live a long and normal life once the FHT is controlled or eliminated. Untreated FHT can lead to death. Few adjustments need to be made to your regular grooming routine for a cat with FHT.  ✂

Deborah Hansen, CFMG, CFCG is the owner of a very successful feline exclusive, house call grooming business, Kitty’s Purrfect Spa. She is also the founder of “Deborah’s Programs”, a complete rebooking system to get all cats onto a regular grooming schedule, and owner and creator of Kitty’s Kopy Kats, a stationary store for anyone who grooms cats. Deborah is the creative talent behind Feline Artistic Creations and an author in multiple publications with worldwide distribution. She is also a Feline Specialist and Correspondent for the National Association of Professional Creative Groomers. She can be found at deborahhansen.com.

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