could they also give the dog activated charcoal to absorb some of the toxic antifreeze as well?
Wikipedia says no, as activated charcoal does not adsorb glycols. Also (my opinion only), since antifreeze is liquid, it’s going to leave the GI tract pretty quickly, at which point activated charcoal would be useless.
Ref: http://en.wikipedia.org/wiki/Ethylene_glycol_poisoning#Treatment