On/off lurker for several WS case follows, so had to finally make an account to comment on this one, but felt I could shed some more light on this topic as an ER vet who has treated many cases of canine heatstroke, albeit some to no avail.
I work in the PNW, where summers are fairly mild but the recreation opportunities abound. We had an unprecedented heatwave at the beginning of June where temperatures reached the low 100s & the night time low was only ~80. We treated (& lost) so many patients to heatstroke in those few days, many from just attempting simple walks around their neighborhood. Most people were not used to the heat & as very few have central AC the overheating process they kicked into gear on their walks, had a hard time getting reversed once they got home.
Dogs don’t sweat, they can only release their heat through panting & evaporative (sweating) through their paw pads. This makes them much more susceptible to overheating than people as the temperature of the ground will directly impact their ability to cool (or will contribute to drive their temperature higher).
I have dogs Oski’s size & coat length, & even here in a more moderate climate, I am very careful about not taking them on exposed hikes with little shade if it gets above 80. In the summer I preferentially hike along or to water, pack water for them, & take plenty of shade breaks along the way. As others have said, in the type of heat they were attempting a venture in, you could not pack enough water to hike comfortably & safely for just a solitary person & dog… let alone 2 adults & an infant. The amount you’d need to pack & number of breaks you’d need to take in the beating sun would make it very unenjoyable.
I wouldn’t attempt a hike at all with a dog when it’s in the 90s unless it was less than a mile & fairly flat & shaded. MOO from seeing the worst of the worst.
On the note of Cyanobacteria/blue-green algae. Not all blue-green algae contains the harmful cyanobacteria & not all cyanobacteria contains the neurotoxin which contains the very fast death factor (VFDF). All of which, needs to be consumed to affect the individual, which is why you’ll find lots of case studies about dogs but few about people (they just can’t help themselves when they swim). They would not be affected by VFDF from contact, they would have had to take at least a good healthy swig of it.
The VFDF hits very rapidly with staggering, seizures, death. Usually within 45 min from ingestion. Most dogs that get this are DOA once they arrive. I have known 1 or 2 dogs that were able to get into a vet clinic very quickly between seizures & death & be induced into a medical coma on a ventilator for days & survive it. These are VERY rare cases (one belonged to a vet & so was intubated/bagged during transport off the trail, which made survival possible).
The harmful Cyanobacteria lacking VFDF (which I think is more common) usually takes several hours prior to onset of clinical signs & is usually more gastrointestinal in onset.
My last thought is that I don’t expect any of the autopsies/necropsy to be too conclusive. All 4 of those bodies sat out in sweltering heat for >48hrs, that will lead to a lot of confounding postmortem changes. Had they been taken off the trail the night they died, I think signs of heatstroke would likely be more readily apparent.
As others have theorized, I think this is a tragic case of overestimation of ability & lack of foresight regarding temperatures. I think it is highly likely the dog was the first to succumb & was likely carried, which lead to more exertion & stress in the people & then a domino effect with the heat & being on those exposed switchbacks. Very sad but hope it is a case that others can learn from when setting out for causal adventures with their pets & kids.
