acepromazine concerns for my 17 year old poodle

have a 17 year old poodle that is otherwise healthy. Blind and deaf but still finds her way to her food and water. she mostly sleeps but gets excited when shes knows its treat time. Today we gave her 1/4 (if even that much) of a 25mg acepromazine tablet to try to clip her nails and clean her teeth as best we could. We stopped regular teeth cleaning by the vet a few years back because her sensative esophagus wasn't holding up to the general anesthesia. We made sure that she didn't swallow any of the build up that we were able to remove from her teeth as we r aware it is bacteria and could harm her heart. This was several hours ago. This evening she was having a hard time using her hind legs but seems to be using them a bit better now. The main thing that has us worried is that she is curled up on my moms lap sleeping heavily with shallow breathing. Ever since she lost her hearing and sight she WILL NOT lay on anyones lap and doesn't even like to be held. It seems to come in spurts of her seeming ok then VERY lathargic. We know its coming time to say goodbye but is there anyone that can tell me if this could just be a side affect of the Acepromazine or something more serious as a result of the acepromazine. We would like to prepare ourselves, however impossible that is to do, if her time to go may be much closer than we thought....like tonight even? Ive never lost a dog so i have no idea what to look for. if anyone can help, I would sincerely appreciate it. Ive had this dog since i was 8 years old and i am 25 now, she is like my sister. her name is Chanel. :/ I am going to miss her