Naturally shed antler pieces: a safe chew?

[Almarine]

Oh wise and wonderful Rat Shack gang!
A friend of the family has fallen in love with my boys, and came over a couple of days ago bearing gifts for the 'furry foursome'. One thing he brought were naturally shed antlers, sliced into round chews. I haven't been able to find any information on them, and so have held off on giving them to the boys.
Anyone know if they're safe?

 

[purinpurin]

I said a bit about giving antlers to pets here: viewtopic.php?p=344049#p344049

Hope you find the info useful!

 

[Almarine]

Thanks for the link--gave me lots to think about!