Petey

Hi all,

I'm trying to help my mom out as she is the one taking care of Petey. I live about an hour away from her. I adopted two brother cats as soon as I came home from college, Petey and Charlie. My mom became so attached that I left them with her when I moved an hour away for a teaching job a few years later. They are now 12 years old and have had no real health issues, until now. They are a big part of our family, especially Petey who is simply the best cat I've ever known.
My mom brought him to the vet a few days ago because he seemed to be experiencing mouth pain while eating. The vet said that some of his teeth were bad and needed to be pulled. Also, he lost 2 lbs. The vet took a blood test to see if there was an underlying issue.
A few days later the vet called and said Petey most likely has diabetes. My mom had also been wondering why he always seemed to be hungry and that the liter box was always full. This seems to explain that. As of now my mom is giving Petey insulin (Lantus) 2x a day. She started just 2 day ago. Petey seems even more lethargic than usual and has diarreah. Is that normal? The doctor does not want to do the mouth surgery until his blood sugar levels are better.
The cost of the surgery is around $1200 and it seems the insulin will cost almost $300 per month. The financial burdens on top of the daily responsibilities of caring for a diabetic cat are stressing my mom out, especially because she is used to leaving them every few weekends to take the train to PA to visit my brother and his family. We are wondering if putting Petey down is the best thing but it absolutely breaks our hearts. I found this forum and thought I'd try to learn a little bit before we make any decisions.
Thank you for any help.

Rob