I thought they were allergic, but I'm not sure. Please help me understand what the science behind this is. Thanks

Dogs love chocolate. But the theobromine in it is toxic to them.

Every dog reacts differently, some can handle a large amount with no ill effects, while others only have a tiny piece and end up at the emergency vets.

It's much safer just to avoid letting your dog get hold of chocolate altogether.

Not going to lie here.. My dog gets Fudgesicle :) He LOVES them, and has never gotten sick, mind yeah, he only gets a few licks a few times a summer... I wouldn't recommend giving them a bunch of chocolate though.

Buy your dog some dog chocolate.

One of my dogs used to love maltesers! Then we found out they could kill her and got her dog chocolate. Its like she doesn't notice the difference.. She loves it!

Yep, dog chocolate is just carob (fake chocolate)
You can even buy dog biscuits with 'chocolate chips' that are perfectly safe for them.