Potassium permanganate can be seriously hazardous as a caustic contact irritant in it's dry form if it entered your eye or mouth.

However, once diluted to a 3-4 PPM solution in your pond per normal dosing guidelines, the potassium permanganate is non toxic to dogs or other domestic pets.

The effect on the pet if it jumped into the pond during a treatment could be eye irritation and surely some discoloration of the lighter colored pelts.

After potassium expends it's energy and becomes amber in color, you will notice that it is harmless to plants which might be exposed to the drainage water should you discharge it across the lawn. The recommendation of professionals for direct exposure to the dry compound is to rinse the affected area in milk and see a physician at once.