My cat (female, approx. 17-20 yrs old) recently had both over-active thyroid glands in her neck removed (but the nodes to do with calcium were left). Shortly after, I noticed a lump on her lower spine on one side and one on the back of her neck. Both seem fused to her inner structure and do not move. She had an x-ray about 2 and a half weeks ago and it showed that the lump on her spine had not invaded the spinal column. The vet said she couldn't be sure what it is without taking a biopsy and if it told us it's cancer it would be too beyond reason to put an elderly cat through what would be intensive spinal surgery to remove it. Since then both lumps have practically doubled in size and she has almost completely lost her appetite, she still drinks a bit. I find the timing of finding these lumps soon after her op a little coincidental. Could they be linked? Could it be something other than cancer? Also, I have a friend who had over-active thyroids and she said when humans have them removed, they have to be put on drugs to replace a normal level of the hormones produced by thyroid glands. Is this the same with cats (she was not put on any meds after the op)? My friend thought this might have some link with her lost appetite. Also, over roughly the last week, she has increasingly lost control over her hind legs, to the point where she can't really walk as they just fold under her, she more drags them, than uses them, if at all. She has also lost a huge amount of weight since an initial increase in weight after the op.
Thank you very much for your answer, I really appreciate your advice.