Hi Mr Gaiman! Recently I saw a video were they claimed that Dog the hell hound actually bit David Tennant and had to be somewhat replaced with cgi, is that true?
No. Ollie the dog absolutely bit David Tennant. He wasn't really replaced with CGI for the rest of the episode as his part in the UK was done, although there might have been a shot or two on the airbase after that where we composited Ollie in. The later scenes in Episode 6 had already been shot.
A couple of months later we shot the end of Episode 3 scene in Adam's bedroom in South Africa and we needed a Dog in it. But we couldn't have brought Ollie to South Africa anyway. Instead we used A Local Dog that looked a lot like Ollie. And we used make up and maybe even a tiny bit of CGI to make him look more like Ollie.