I think some of you are being a little hard on Dorothy

.
I really have no idea whether she was advised not to do the show ahead of signing up, but just on the face of things, it seems there was a pre-existing problem which she was able to skate with and expected/hoped to be able to dance with, too.
A new discipline obviously presents new challenges for the body and it didn't work out this time, regrettably.
There can't be an athlete or dancer (or human being over 50

) who isn't carrying some kind of chronic injury or pain and I guess you just can't know - until you try - whether you can do it or not. Jennifer Grey had a history of neck (or back

) problems and had a lot of pain when she took part, but she won. Louis (on SCD) aggravated a pre-existing back injury but was able to push through. You can't rule out from the show everyone who's vulnerable to injury...
It sounds as though Dorothy was risking too much, so she's done the right thing. I'm very glad it happened at the first elimination stage and someone else got the chance to continue.
I'll miss her - she seemed lovely and had potential... and I'll miss Tris, too