Dog Owner Thinks Heat Exhaustion Led to Death on Hawaiian Airlines Flight

The owner of the 2-year-old emotional support dog who died while traveling with Hawaiian Airlines believes his pup may have suffered a very painful death ... and he wants authorities to investigate.

The dog, a pit bull named Louis, had a body temperature of 107 degrees and his right paw was bloody with nails worn down to the quick ... according to the necropsy results, obtained by TMZ. For reference, normal body temp for dogs is around 101 or 102.

The owner, Dr. Randall Carpio, says the findings lead him to believe Louis died from heat exhaustion or heat stroke. He also claims the necropsy is missing key details surrounding the death.

He says Hawaiian Airlines ordered the testing while keeping him in the dark about Louis' death.

TMZ broke the story ... Louis died July 21 while traveling from Kona to Honolulu, but Randall says the airline gave him no explanation why.

The dog owner's attorney, Evan Oshan, filed a complaint with the Hawaiian Humane Society, claiming the airline isn't being transparent, and called on the state to investigate. He says the complaint was also sent to the Hawaii Attorney General's office.

In the complaint, obtained by TMZ, Randall says Louis was given a clean bill of health 48 hours before the journey ... and he claims airline agents told him the pup died in the animal holding facility at the Honolulu airport during a layover.

He recently received the dog's ashes and toys, but, obviously, he's looking for more answers.