The amount of D Con or rat poison or mouse poison it takes to kill a dog depends on the weight and size of the dog.
Smaller dogs it would take less D Con to kill the dog while larger dogs would require larger doses of D Con to kill the dog.
For a lethal dose of D Con to kill a dog it takes between 0.2 and 4 milligrams of brodifacoum for every kilogram of body weight of the dog.
So for example if the dog weighs 75 lbs then the dog would need to eat 4 ounces or more of D Con for it to kill the dog.
Smaller dogs may only need to eat 1 ounce or 2 ounces of D Con for the dog to die of D Con poisoning.
If your dog did eat some D Con you need to take the dog to the vet for treatment or they could die.