3-4 inches is a little small IMO, I would shoot for 5-6". Besides the obvious hazards of giving bones you should know that it wears down their teeth pretty badly. I wouldn't give gnawing bones on a regular basis.
Mine do well on rawhide. We have 5 retriever rolls around at all times. They also get raw marrow, but I have one that will get xtreme runs from raw bones.
My dogs are still enjoying their Christmas bones. They are raw shank bones from the butcher, about 4 inches long. They most often leave them outside, but will bring them into the kitchen. People who don't know otherwise, worry about germs, but my dogs never ever get sick and the bones are enjoyed for months.
Hi.... I use raw femur bones from my butcher. I have them cut into about 4/5 inch lengths and the knuckles chopped off(these granulate). I use pressed rawhide rolls/bones(big ones) and I use the large claw foot nyla bones.
My guys love their Himalayan Dog Chews. They are made of yak and cow milk with a twist of lime. They are an everlasting cheese chew. You can see them at himalayandogchew.com
They also really like Moozles, big dehydrated cow snouts made by Merrick. They last all day and even my old girl with nub teeth can chew on them.