It is the Boron in the Borax that is the effective mineral. Boron supplements are dirt cheap, even the more expensive Boron Citrate is cheap (use for those with absorption issues).
You can use Borax as a source, but you need to take ~10x the amount to get the Boron you need. Daily dosage of Boron is ~3mg more if you have loose fluoride and aluminum.
Those dogs don't watch TV so they are more attuned to what is real...