Hypothyroid Cat

I did annual lab work on my cat, Chunky Monkey. She's chunky. We've tried to get her to lose weight with calorie intake and RC Satiety. The lab work shows low thyroid and my doctor called in a Free T4 ED for her. I've been reading hypothyroidism is extremely rare in cats. If she is a true hypo, is the treatment the Methimazole or Thyro Tabs? Is it basic expectations like if a dog were hypothyroid? Thanks!

Hello.   In full disclosure, i have seen about two hypothyroid cats in my whole career - and these were cases that other vets showed to me, chuffed to bits - not because the cat was ill, but because these cases are rare as hens' teeth and they'd managed to diagnose one.  The first thing I'd be doing in your vets shoes would be calling up an expert to ask if they needed any more tests.   The most common cause of hypothyroidism in cats is actually iatrogenic ie they have been on hyperthyroid tablets and overdosed (hyper means high - hyperthyroid tablets lower the thyroid back into the normal range, but if the dose is too high it can go too far.  This is why we check the bloods of hyperthyroid cats on treatment every so often).

Thank you for the reply! Her vet ordered a more sensitive thyroid test today but said it takes several days to get back. She's not currently taking any other medications. Could this just be a lab fluke?

Assuming that your cat isn't on thyroid meds, there are some cases of feline hypothyroidism that do occur.   Of these, according to Mereck's veterinary manual, the majority happen because the thyroid is unable to respond to thyroid stimulating hormone, which would usually stimulate thyroid hormone production.  Apparently there is another, obscure, kind, associated with head trauma.  Some of Weight gain, dullness, skin changes, sometimes low heart rate and appetite might be seen.  I beleive that the diagnosis is usually reached by comparing the thyroid hormones (low) with thyroid stimulating hormones (high).  Please do let us know what is found.

I guess that any result *could* be a lab fluke, but you are desribing signs consistent with hypothyroidism, so sending off the other tests sounds to be the right thing to do.