Here are some clues:
1. Kept as house pets, along with lions, by Egyptian royalty and high-society.
2. Perfect running machine and the fastest cat on earth.
2. Keeps head steady and eyes focused while running after prey.
3. Hind legs enable explosive power.
4. Sometimes mummified and buried with owner for its speed and ability to take owner's soul to the afterlife more quickly.
5. It is the size of a large dog.
Answer: Cheetah