
Hi Kristian,
Congratulations on your new puppy - you must be delighted. This idea of fasting a dog for 24 hours (never heard of it being increased to 36, though) was first put about very many years ago, on the belief that 'in the wild' dogs wouldn't eat every day, so being hungry occasionally was natural and therefore good for them. Others believe that, given the choice dogs 'in the wild'
would eat every day, and that enforced fasting is therefore unnatural.
I have never fasted any of my dogs, and they generally (barring accidents) live well into their teens. Do what you feel most comfortable doing.
:)