Somewhat yes. The lamb(who they treat as as an infant) towards the beginning of the movie is taken from the house by her mother and the two main characters panic trying to find her.
Ending can be seen as happy or sad depending on which character you focus on...
Spoilers...
I saw it as happy for the lamb-child because she leaves with a goat-man who is probably her biological father. It's not a happy ending for the human couple who took the lamb-child away from her mother. Lamb-child seems to be sad to leave the humans but earlier in the film she also seems to know she isn't human. So maybe she's going to be happier with her father.
Cat is not hurt in any way, nor is the 'lamb' the main character of the movie