I had been thinking that Dorsal is the same as Posterior and Ventral is the same as Anterior since i had read that but when i checked in google images for these anatomical terms for a horse (just to strengthen my concept), i found that in a dog Dorsal is not the same as Posterior and Ventral is not the same as Anterior.

How is this possible? I have checked many websites but all state that Dorsal is the same as Posterior and Ventral is the same as Anterior. Am i going wrong somewhere.