Drooping ears is a trait for domesticated animals that very rarely occurs in the wild (elephants are an exception). Almost all species gain this trait when domesticated. A Russian experiment successfully domesticated foxes over 40 generations, and in that span their ears drooped. – WTF Fun Facts
Source: https://blogs.scientificamerican.com/guest-blog/mans-new-best-friend-a-forgotten-russian-experiment-in-fox-domestication/
WTF Fun Fact – Drooping Ears Trait

Why don’t cats have dropped ears than?