Claymore, if it's online, could you please post a link to the story? I did Google it a bit -- some horror stories about thieves in France using exhaust fumes deliberately to rob people sleeping in caravans, but nothing about pets dying on long trips.
I had a long wheelbase Landrover for many years, latterly with a Discovery engine in it. Snorkels are air intakes - exhausts on wading 4x4s don't need to be on 'periscopes', and aren't (at least I've never seen nor heard of one).
E.
PS: have been to Galloway ourselves on holiday - you live in a beautiful place, and the night sky there is just wonderful!