It is so easy for conscientious people to suffer as you are!

My son did not return to the rescue vet contract..he was allowed one
visit after adopting the sick older cat. She has had many problems since.
(he went to his own vet instead).

I don't think vet medicine is totally trustworthy yet. So anything can happen to
anyone anytime there. It was just very unlucky that it was Moonshadow.
It is kind of spooky that his name fits now...very spooky.

Let me share this with you. My son's older rescue cat...had an abdominal hernia in her side, when found. The rescue vet "fixed" it, and gave her a clean bill of health. She still had a draining hole at the incision site when he adopted her. She was pregnant when found and the kittens removed when the surgery was done (a spay with the other hernia repair). When he took her to his vet, he was given Clindamycin for her to help it heal. Then she became ill with a urinary tract infection, and they overmedicated her with Elavil. Then they said, do an ultrasound and found congenital kidney malformations (very small), poor blood work, and told him she had a very short life expectancy. So he bought a kidney formula food online for her..and she seemed better. But before Xmas she became very ill, vomiting and almost comatose so he took her in to an emergency vet. $800 dollars later they said she had bacterial hepatitis, put her on IVs and said nothing was wrong with her kidneys! We saw her at Xmas and she was so much more lively, happy etc. So all that time, 3 vets, and tons of $$ and only now she is happy? Could she have had an abscess in her liver all this time? Maybe? But still no one knows. My son refused the ultrasound for the liver--he is getting fed up with vets. (we had to help him pay the bill, as a matter of fact! ) On the upside, my son and his roommate have alot of fun daily with both of his cats..each day that joy is a gift.

So anytime, any unexpected thing can happen. It is not your fault, Chemar.
Little Moonshadow can live indoors and have a comfortable life with your family. He may regain some sight. But prepare yourself and your son, that his weak constitution may rear up again in the future. One just never knows.

And he may be a gift to you in other ways.. you just have not experienced that perhaps yet.

This is such a sad event. But you know he is young, and will adjust. An old cat would have so much more trouble!

I am so sorry you all had to go thru this.

I'd like to add: rescue and Humane Society places, try to do as much as possible with the lowest costs. That has been
my impression. Neutering baby animals because they think the adoptive humans will not follow thru, or using as little as possible resources, seems to be common. My son's vet said his cat (which cost him $75 at adoption) should not have been let go in the state she was in (she weighed 5 lbs and could hardly walk she was so weak). He did not go back to the rescue place (but he wanted her, and thought her mature kindly presence would help with the out of control kitten he already had as this mature cat had had her own kittens),
because it was 100 miles away! (probably lucky for her). So others reading here might consider this scenario and pick their own
vet for follow ups.