At least you willfully attempt to take care of your pets. This person decided to get a pet with no knowledge or no desire to understand the necessary medical requirements to keep their pet healthy. Which to me is tantamount to animal abuse. It's the same as willfully keeping food from an animal, if you willfully keep medication from an animal, and then they suffer a debilitating condition because of that decision.
Luckily, the person decided upon treatment. But not before asking "is the treatment dangerous"? Well yes, it's dangerous, with death or paralysis as a worst case scenario. But seriously? Do you mean, dangerous as in not giving your dog heartworm medication so he ends up getting heartworms and would eventually suffer right sided heart failure if we didn't catch it dangerous? I will never understand people.
EDIT: And also, a good judge of ideal weight is that you should be able to feel your pets ribcage when you touch his sides, but not be able to see it when you look at him. If you can't feel it, he's got too much fat over it. If you can see it, he hasn't got enough.