Irregular breathing

[Pramee]

I've got a pregnant mare who ia panting all the time. Before she got pregnant she used to take longer than other horses to cool down, when others would take 15 min,she would take about 2 hours to return to normal rate of breathing. Im getting worried about her,shes due to deliver in 2 months. The vets havent a clue whats wrong with her. One mentioned water in the lungs then stopped treating her saying that he didnt know how to treat her, so we arent even sure if its safe to bath her. Despite the heavy breathing she doesnt sweat alot. The teperature here has been constant at around 30°c for the last month or so. Sri Lanka is tropical so this is the norm here. If anyone has any ideas please mail asap!
Thanks