After a lifetime of processed foods, you’ll want to start slow during this transition to raw for your senior pet. Just like with any pet that is new to the raw meat diet, start slow. Their first raw meal should be 3/4 what they normally eat and 1/4 raw meat. You can slowly work your way from there. Pick up some digestive enzymes at your grocery store during their transition and give them a pill with each meal until the bottle is finished. By that time they should be fine with eating raw.
As for the raw meat selection, begin with bland – chicken and turkey. Avoid the richer and fattier meats like organs and duck until your senior pet is used to the raw diet.