Its because if Ras had asked her husband to heal Sing, he would have killed him instead. Treating Sing as a dog is Ras's way of keeping him alive because he husband is deeply possessive of her now. It does not help that Sing used to originally have a handsome face and there were rumors of him having a special relationship with Ras. All noble ladies closest attendant is usually female since they attend to their masters in the bedchamber and personal rooms too. The only way to keep Sing alive by her side was act like she cared about him only as a pet for amusement, not just to protect him from her Husband's jealousy but also to prevent others from targeting him as Ras's weakness as that Bitch had done before. Throughout the story, though she call him her dog and give him the muzzle, she actually treats him really well and protects him indirectly through guard dogs, which Sing knows. They have a very complex relationship and I love it because its so clear that they don't have any romantic interest in each other, but still care for the other.

So... The Ras husband healed Nika or whatever the pink hair bitch but Ras never, I don't know, thought of healing her assistant? Am I the only one who thinks its weird...?