Poor Tia and poor your OH.
A few days ago we came out of our local park a different way to usual, onto an open track with a busy main road at the end close by. Ellie had gone to chase a squirrel so was out of sight, I manically called her but she didn't appear. Then I saw a flash of white on the road and was convinced it was her. My stomach went, my legs went and I could hardly breath. Then Ellie appeared and I don't think I have ever hugged her as hard as I did then. How your OH felt to know that Tia had been hit by a car, heard her scream and then to see her lying on the road, I cannot honestly imagine, it must have been unbelievable terrifying for him.
I am so pleased that Tia is not badly hurt, Gari was definitely looking after her. Hope that your OH is starting to feel better and realise it was one of those things that he just couldn't foresee.
Have just read your other thread and am so sorry you have not been given a definitely diagnosis, it must be so frustrating for you.