Via tells August to come quick and yells that it's not about him when he refuses to apologize. She says that Daisy is sick, and Mom needs to take her to the vet, so August needs to say goodbye. August allows Via to lead him to the kitchen, where Daisy is panting on the floor. Mom is crying and admits she's not sure if the vet will be able to fix Daisy. When the taxi arrives, August tries to stop Mom from carrying Daisy out. Mom explains that Dad will meet her at the vet, and August needs to say goodbye. August does as he's told and watches Mom get into the taxi. When the taxi pulls away, Via and August hold each other and cry.
August's initial reaction here shows that he's still self-absorbed, especially during times of heightened emotion. This is a mark of immaturity that's thrown into even sharper relief as August is confronted with the possibility of Daisy's death. Though Mom is clearly doing the right and kind thing by seeking help for Daisy, even if it means euthanizing her, August's unwillingness to let this happen shows that he still has a long way to go to understand that this is actually the right thing to do.