[anonymous]

http://www.embracepetinsurance.com/blog/harmful-side-animal-sourced-dog-chews (excerpt below) click on link for full article.
Cow hooves and pigs ears are what the name implies. 
Marrow bones are from the long bones of cows and pigs.
Rawhides are the skin of cows. 
Antlers come from either deer or elk. 
So what do you think bully sticks are?  Think about this one.  Give up?  They are bull penises! Hmm.
There are some dangers with all of these items. All of these have the potential and can cause intestinal obstructions, but equally important are the dangers that come from the way these are processed.  They are first soaked for hours in a caustic lye solution to digest the undesirables off the skin and then to remove the lye the skin is then soaked in bleach solution.  Sounds yummy. Many of the rawhides come from China where they have been known to use arsenic compounds to preserve them. 
There is no regulation of rawhides or pigs ears.  You really have no idea where these come from.
Marrow bones and antlers cause many broken teeth.  A good rule of thumb is if you don’t want me to hit you in the kneecap with it, your dog should not be chewing on it. I can not tell you how many expensive extractions are the result of dogs chewing bones.

http://skeptvet.com/Blog/?s=bones

Also, you can use the search engine here to look up topics. I am sure that if you Google enough, you will find articles to support your opinions (whatever they may be).
I have found that I get the best results by listening to a veterinarian that has actually examined the pet in question.
I prefer science based veterinary medicine.