Clinical pathology diagnostic challenge : case #20

Signalment: 3 year old, intact male Golden Retriever, canadian champion.
History: owner was driving back with the dog from a competition 6 hours away; upon arriving, the owner found the dog in lateral recumbency and unable to stand, outside temperature: 32 degrees C.
Physical exam observations: dark red mucous membranes, severe dehydration, hematochezia, weakness; initially urine couldn`t be obtained, rectal temperature: 40^o C.