The other options do state possible recruitment, not garunteed, and as I said twice now.
Just because we finish the War Dog research now, doesn't mean everyone on MB will suddenly have a fully trained and fully grown War Dog. It will take time to give everyone a Canine Partner, so we should start now, so we can start partnering up our soliders before WW2 starts. Not to mention who knows how crazy the next few turns are going to be after we get ported or what fire's we will have to deal with. So I'd like to get it done now before more pressing subjects appear.