What do you advise if I have a cold toes under my cast after surgery?

Check capillary. Return to make sure it is instantaneous. In general are your feet cold before surgery?If not you should discuss with surgeon.Noral cap return would indicate your circulation is likely fine but it is plausible the cast is tight with pressure on nerve and that's why toes are cold. Yu could try rubbing in a cream with l-arginine and see if that changes anything, .