Hi, Welcome to JustAnswer. I am a licensed veterinarian and I'm happy to help you and Maggie.
It's not unusual for cats to have an adverse reaction at first to the methimazole. This reaction includes loss of appetite, vomiting, diarrhea and dehydration. Fever is not a normal reaction to methimazole, so I wonder if she wasn't ill with something else.
Normally, when a cat reacts to the methimazole, we take them off the medication for a few days, and then try giving them 1/2 the full dose for one week. If all is OK, then we put them back on a full dose and usually quite successfully.
You could try this and allow her to eat what she likes. Also, methimazole can be made into a transdermal cream which can be applied to the inner surface of the ears. This would go directly into her blood stream and avoid any irritation of the stomach.
There is also radio isotope therapy for hyperthyroidism which will also shrink any extraneous thyroid tissue in the chest cavity. She may end up on a thyroid supplement for the rest of her life, but she also may not need such supplementation.
These 3 alternatives would mean she doesn't have to eat the Y/D which she seems to dislike! Do any of these seem feasible to you? Dr. Barbara
Thank you for your answer Dr. Barbara. The cream alternative sounds like the easiest solution to me. I have an appointment with the vet on Saturday so will ask about the possibility of trying this method for Meggie.
I'm glad to be of help. The cream is used by a lot of clients. . . MANY cats are so diffictult to pill! Just remember to avoid contact with your skin when applying the cream as you will absorb this too and it will suppress your thyroid function. Your vet, or the compounding drug store should supply you with latex gloves to wear to protect yourself.
I'd like to put you in for a follow up after your next appointment. There is no further charge for you, and I would really like to hear what you decide for Maggie. Please don't hesitate to respond now if you have any further questions or concerns.
Thank you and take care!