Below is an excerpt from http://animaldentalspecialist.com/safe-and-appropriate-chew-toys-for-dogs/
Click on link for full article. Hope this helps.
Fractured pet teeth are one of the more common dental problems encountered by veterinary dentists. Broken teeth, more often than not, have exposed pulp tissues that subsequently become infected. Just like for humans, apical infection (apical periodontitis, dental “abscesses”) will occur in a matter of time. They are painful and cause exposure of the body to chronic bacteria infusion and inflammation. In most cases, the problem is caused by dogs being allowed to chew on objects that are just too hard for their teeth. These objects may actually be harder than the teeth. It is important to remember the evolutionary function of carnivores…they are meat eaters. The function of carnivore oral behavior is to grasp, pull and hold prey. This is followed by cutting and tearing meat before crushing and gulping. Carnivore teeth are not designed to chew bones or other objects harder than the teeth. Starving wild animals often have only bones to eat, however, they also break their teeth, which places them at a survival disadvantage (survival of the fittest). Wild carnivores that do eat bones are usually doing so from freshly killed prey. Fresh bones are softer, however, they still can lead to traumatized and fracture teeth. Dental treats and chew objects should be considered as only part of preventative dental health care (please refer to information on dental diets, chews and antiseptics). In conjunction with daily tooth brushing, dental diets and regular professional cleanings, toys and treats can play an important part of oral health care maintenance.
Strictly avoid bones (cooked or uncooked), cow hoofs, pig ears, hard & thick rawhides, plastic or nylon bones, and large ice cubes. Tennis balls and other objects with abrasive surfaces should also be avoided as these have a sandpaper-like effect on tooth structure that damages and may expose the pulp. The flatter, softer rawhide chews have been shown to be safe and effective in reducing the rate of plaque accumulation. C.E.T. Hextra rawhide chews contain Chlorhexidine which enhances their effectiveness.
When trying to select safe chew objects for your pet, there are two good approaches:
General rules of thumb.
Use products approved by the Veterinary Oral Health Council (VOHC)
A. Rules of Thumb
You want to be able to indent the surface with your finger nail. Surface has some “give” to it.
“Knee Cap Rule”: If you hit your self in the knee with the object and it hurts, it’s probably too hard/heavy for your dog.
“Hammer Rule”: If you can drive a nail with the product, don’t allow your dog to chew on it.
Also avoid objects with abrasive surfaces like Tennis Balls and Frisbees.
If you cannot flex or break the product with your bare hands, it’s probably best to avoid it.
Please take note: you should always monitor your pet when they are chewing on anything. Verify they’re not gagging, trying to ingest too much at one time or attempting to eat an inedible product.
B. VOHC approved products
Although not all safe products have VOHC approval, using products with the VOHC seal of acceptance is recommended as these products have successfully met pre-set requirements for veterinary dental efficacy and safety. A complete list of VOHC approved products can be accessed at http://www.vohc.org.
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