disease

Do you need to get a vet to check them for any diseases first or is the risk of cross species contamination non existent in most cases? For example if i have a cow that i'm planning on having sex with do i need to get a vet to check her out first to make sure she doesn't have any diseases...

EDIT : Appreciate your kind replies, thankyouverymuch!!! ☹️

hi all my girlfriend is pregnant, she is afraid to play with dog i just want to know anyone experienced this situation? is it safe? she is two month pregnant ... she is active with our rottie for 5 years.