how to talk to parents about weird things my uncle does with dog

hi, i’m not so sure where to goes as this but i’m not sure if i’m over reacting or if i should tell my parents so basically i have my dog he loves to go to the bathroom and just lay on the floor because it’s cold and it’s been pretty hot in california and the ac blastes in there (contex) and there been a few incidents where i had caught my uncle once my dog stayed in there and he didn’t even care and went to shower and had hot steam around him and my dog was constantly whimpering and me and my mom came from the bank to see that. and he brushed it off like nothing and my mom thought it was weird and i just kept my dog in my room and a couple of days ago my dog was in the bathroom again because i had my door open and he went into there so my uncle had went into the bathroom and he dosent care to even tell my dog to go out and pees infront of him and then laughs and i’m not sure if he gets off to it or what but im concerned and im not sure if i should talk to my dad or how to because its his brother