The good news is that Toby is twelve weeks and three days old, eating, playing, and growing.
The bad news is that on Friday he decided to play-attack the dog's face and she nipped him when he kept on after a warning growl. It was a matter of seconds and Matt couldn't get there in time. No serious damage, but it could have been very bad indeed; her teeth shaved his upper eyelid and tore the third eyelid on his left eye. The eye is untouched, the lid is healing nicely, and he's busy hating his antibiotic ointment.
Daisy was immediately wretched and crawled into a corner as Matt dealt with the injury and called me to come take them to the vet (I was at an appointment). When I saw her a couple of hours later, she was still miserable; I haven't seen her so sad since Buddy died. We boarded her at the vet over the weekend and got her a medical exam; she's healthy. We also talked to several knowledgeable people about how to handle the situation.
We asked: should we euthanize or rehome a 9-year-old dog who had never harmed a cat before and has lived with them all her life? Should we rehome a kitten whose history of digestive issues means he is still having trouble learning to use the litterbox? (We have five, count 'em five, litterboxes scattered around the living room right now so he is always close to one, and he's doing better.) Or should we figure out ways to keep them apart while we continue to train Daisy, work with Toby to be less aggressive at playtime (yes, we have worked on this and continue to do so), and wait for him to grow up and calm down? We have plenty of doors in the house.
There were differing opinions, but the third option got several positive answers and became our choice. Toby and Daisy are never in the same room when Toby is out playing, but they can sometimes see and smell each other when he is safe in his crate, where he sleeps. Neither of them reacts badly to the other in that situation. They both get plenty of human time and play time because we both work at home. Although Daisy is not a yard dog, she can tolerate some time alone in a room if she knows it's her job to stay, and she loves sitting in the car when it's cool enough for her to be there. They are both with people who know them, love them, and are committed to their welfare.
So far, so good, and if it changes, we will reconsider. They will not be together unless and until Toby has stopped flying at faces. We will check Daisy for any sign of aggression: she’s on probation.
I considered not posting about this because it's bound to be a hot-button topic, and decided to do so because it's the truth and there are no perfect answers. I understand that some of you will have strong feelings about this. And if you know exactly what you'd do...well, I thought I did, until it happened.