Actually vieleds are suposed to be one of the easy ones to take care of. I have two vields and they are both doing very well.(male and female) I dont know if you have done much research or not but acording to one of me books about chameleons says... mbd is caused by an imbalance of phosphorous,calcium and/or Vitamin D3. I hope thos reply is helpful to you and if you have nother question about common diseases in chameleons just ask.