There are some MAJOR direct effects from it's proper dosing.
"We give a couple of MLs to each dog once a month and I know it's very safe to use ie you can over dose the heck out of them with out harm."
All dog breeds cannot tolerate ivermectin, it will cross the blood-brain membrane in several breeds and will cause seizures/coma at best. It can be overdosed and cause a stupor or stroke type symptoms in more than several breeds. If it is given to a dog with a large microflaria load it can cause embolism. It will kill the parasites you mentioned as well as demodex and ticks, but will not kill whipworms or tapeworms. I was a little concerned that someone would decide to give a couple of ML's to their beloved Sheltie after reading this and kill it. But in general, you are correct...it works well for many parasites in most breeds under most conditions.
Turtles and tortoises should not be given ivermectic for the same reason some dogs can't take it. It also crosses their blood-brain membrane.
Nothing personal, just a word of caution.