Yikes! That is an extremely high starting dose.Well-I Her liver enzymes are elevated, so he's starting her on 5 mg of the methimazole twice a day.
I really like this vet so I am sticking with them.
I have not treated a cat for Hyper-T........but.......everything I have read recommends a starting dose of 1.25 - 2.5 mg.
Here's Dr. Mark Peterson, the discoverer of feline Hyper_T on dosing:
Here's one owner speaking about common Vet dosing errors.....and what can result:Initial Methimazole Dose
The initial methimazole doses used vary depending on the cat’s pretreatment serum T4 value and the size of the thyroid tumor. In general, however, most cats are started on 1.25 mg to 2.5 mg of methimazole, administered twice daily (4-7). This dose is adjusted according to T4 measurements (see below), as well as the cat's clinical response.
In cats that fail to respond and remain hyperthyroid, the daily doses are slowly titrated upwards to lower serum T4 concentrations into the desired range
http://animalendocrine.blogspot.ca/2012/08/how-to-dose-and-monitor-hyperthyroid.html.
I read your comment about liking this Vet.........so, you may naturally have some difficulty with the info I've given you.Many vets are not up-to-date on the latest protocols for methimazole dosing, unfortunately, and therefore frequently order doses that are much too high to start. This can result in a cat becoming very sick from the side effects, or even worse, become hypothyroid (T4 too low) which will also make them sick and sometimes have adverse effects on the kidneys. It is, therefore, very important to insist on starting at the low recommended starting dose and increase the dose slowly so that the cat's body becomes acclimated to the medication.
I've sent a PM to someone here who I know has personally dealt with Hyper-T - hopefully she can come by and assist.