Joey

Joey was 3 months old last Thursday and we almost lost him this past weekend and he's not out of the woods yet. He had a severe case of diarrhea overnight on Friday that led to dehydration that led to his kidneys starting to shut down on Saturday. We had to hospitalize him Saturday night and he's still there now on iv fluids. He was 100% fine Thursday night and Friday morning he was completely caked in diarrhea as was his stall. My vet came right out and got blood work going and antibiotics/ anti-diarrheal meds started. She took more blood Friday afternoon and again Saturday morning as we were watching his hydration levels very carefully in this heat. He completely stopped drinking, eliminating or even getting up on Saturday and Saturday afternoon he was lame in his front right leg. It would take me over an hour to get him standing to go outside to hose him down. High fevers (104.5 was highest) and completely lethargic. His white blood cell count was very low (yes, low) as was his sodium, chloride and glucose. He has a mineral block in his stall that he uses but I've always had an issue with him drinking enough water. He drinks very little normally and I keep him stalled with fan during the day when hot (which is every day lately). Equitea and some type of apple flavored electrolytes offered in addition to regular water also refused. I sat for hours with a syringe trying to get fluids down his throat until my vet could get here as she was at another emergency pretty far away.
Sunday evening, after pumping him so full of fluids that he was constantly dripping urine, his kidney levels were back to normal and his white blood cell count was better but still running a fever and still lethargic.
As of this morning, his appetite is good and he's drinking a little better. They have started weaning him off of iv fluids. He is still very lethargic which is worrying them a lot because they think he should be acting more normal at this point and they are pretty clueless as to what is causing this and where to go from here. We are waiting for this mornings blood work results to see his kidney levels and will keep monitoring those once he's completely off of iv to make sure his kidneys are not permanently damaged. They are discussing doing ultrasound and x-ray to look at his entire gi tract.
He has been eating shavings from his stall to the point that they have a muzzle on him so he won't eat any more. Found out that the new shavings that my feed store is carrying (the other shaving company went out of biz so had to switch) are not 100% pine. They are pine + mill by-products from furniture makers. #1 wood used in furniture is oak which is toxic to horses. Vet says most toxins can be ruled out because they would show neurological effects and he has none. The toxins that have gi effects would be long gone from his blood stream and even by Friday late morning when they pulled blood, would have been hard to catch as would have been mostly gone. If he was bit by something, there would be swelling and he has none.
There has been the thought that this was heat related but they are now sure that it is not caused by the heat, altho it was definitely a factor in his dehydration.
Like I said, he's lethargic. He walks around like an old man. Shuffles his feet. Moves VERY slowly. Collapses when he lays down. Falls asleep while eating or grazing. Sleeps A LOT. Zero energy.
Also discussed this morning that he's 3 months old and hasn't lost any of his baby fuzz yet. not shedding at all. They are going to shave him to help with the heat.
Has anyone ever seen/heard anything like this? any clues? suggestions? ideas? I'm getting desperate. I refuse to loose him but I'm out of ideas of what it could be and have gone thru everything in my head over and over again of the last few days before this happened and, nothing... Vet has nothing at this point either.
I'm rambling but I think I remembered everything and I hope it's clear.