If it was an attempt to poison your dogs, it was a feeble one. A dog might get sick on chocolate cookies, but it probably won't have any negative effects. Probably. If they were soaked in antifreeze -- that would make a huge difference.
There are evil idiots out there. I suppose I would look at the environment. Could someone walking down the street or sidewalk toss them over your fence, or did they have to travel over your lawn several yards and then throw them over the fence? If the first, I would probably think, someone who is stupid and litters, but not necessarily malicious and intent on harming you or your dog. If the latter it is more puzzling. As we have mentioned, chocolate cookies probably won't hurt the dog, so unless they added poisoning, I don't know, it i just weird.
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