The following is my recipe for ice cubes made from leftover roasted chicken.
1 chicken carcass. Remove the skin if you really charred it up. The skin usually has salt and other spices on it which may not be healthy for the dogs. The dogs love the fat flavor so I do keep the skin from the bottom of the chicken on.
A bunch of carrots. I usually grab some from the garden and just throw them in, stalks and all, but a handfull of baby carrots would do well too.
Sweet Potato or leafy greens are great for your dogs too. For greens, chop them up 10 minutes before the end of the boiling so it doesn't impair the chicken flavor.
Cut up the bones of the chicken so any leftover marrow can be released and cover with water. Simmer for 3-4 hours and then strain the broth. The carrots or sweet potatoes can be mashed and be added to the broth or the broth can be frozen just after straining. Place in ice cube trays and freeze until hard.
Your dogs will love them!