Plain tripe only
Either lamb / Ox or Beef Tripe
If your dog gets loose stools on tripe, then move on to next phase which contains bone.

Chicken and tripe / Turkey and Tripe
10% bone

Duck and tripe
10% bone

Ox tripe with chicken or duck 80-10-10

Start mixing in some red meat 80-10-10s with tripe 80-10-10s as we want to introduce new proteins slowly or if feeding DIY (balancing yourself) mix new chunked proteins with proteins your dog is already used to.
If introducing pork, British pork is a great protein, or fish please introduce very slowly as pork may be a little rich until some dogs get used to it and the texture of fish can mean it makes a re appearance until your dog is used to it.
If your dog regurgitates and they want to re eat it its perfectly fine for them to do so, this is a natural process for dogs.