These organs include:
• Liver
• Kidney
• Pancreas
• Lung
• Heart
• Splin
• Tounge
• Trachea
• Gizzard
• Tribe
• Brain
• Eye balls
These organs are highly nutritious as they are more densely packed (with vital nutrients) than standard lean muscle meat. In addition to containing high quality protein and fat, they are also incredibly rich sources of: vitamin A (helps with vision and growth); vitamin B (helps with metabolism, digestion and red blood cells); vitamin D (helps dogs regulate the balance and retention of calcium and phosphorus); vitamin E (which is one of your dog's defenses against oxidative damage).
However, organ meats should only be fed in small portions, as too much at once will lead to nutritional problems, with your dog receiving too many vitamins which can cause joint problems, heart disease, behavioral changes and more! They should only be fed to your dog if you know where it was sourced from, to prevent bacteria and parasites which can be harmful.
If your dog is not used to eating raw organs (or raw meat in general), you should start them off with small portions with strict supervision until they get used to it.