Welcome to YT and bless you for not only rescuing but for taking a wee lil baby that is blind.
I don't have knowledge of blind dogs, just my senior who became blind as she aged.
It's going to be a rough start with Sadie until she learns where in the house things are. Do not move anything unless it's for Sadie's safety. She is only with you a couple of days, it will take her time to learn the entire home or the rooms she is allowed in.
Your two other pups will sense she has a disability, when a new baby is bought home with other dogs there is an adjust time your dogs will go through before accepting the new kid.
As for Sadie sleeping on the bed with you, you can get a small carrier and put her in it at night and set it on your bed, one that she cannot get out of, she will smell that she is near you and that will be a comfort to her, that is if she will go in it.
What horrible owners she had to not rush her to vet when she was bitten. Then just cast her out of their lives, just horrible. Sadie being blind yes does feel safer with all 4's on the ground. When my senior was becoming blind then lost 98% of her vision she did not want to be held, she preferred to stay on the floor.
Hopefully there is a member that has had experience with a pup that was born blind and can offer more info.
You have a lot of love for this new baby, she will sense this and in time will accept cuddling with you when your sitting on the floor with her, if she didn't have it with her prev. owner. Everything is done in baby steps. Sadie has to learn to trust you and new fur sisters.
Since Sadie was born blind and is an older girl darkness is the only thing she knows and has adapted to it.
Adjusting to her new surroundings will be her toughest challenge, but she will get through it.
__________________ Joan, mom to Cody  RIP Matese  Schnae  Kajon  Kia  forever in my  A House Is Not A Home Without A Dog |