You could look into a pet cooling bed like this one: https://www.amazon.com/dp/B07SR9VQQK/ref=cm_sw_r_cp_apa_glt_fabc_WNSHE7SXKJ6W8CNYPZ3Z or something similar. He may also appreciate some frozen treats like tuna juice ice cubes. If it gets super hot and he is having trouble you can also get a washcloth wet with cold water and wring it out REALLY WELL before placing it on him. Good luck!