National Geographic photographer Steve Winter has spent most of his adult life shooting wild cats. Photo: A 14-month-old cub, cooling off in a pond, is riveted by a deer that appeared near the shore. Tigers are powerful swimmers; they can easily cross rivers four to five miles wide and have been known to swim distances of up to 18 miles. (Photo by Steve Winter/National Geographic)

Cat lounges and makes itself at home at the new Cat Café by Purina ONE on Wednesday, April 23, 2014 in New York. (Photo by Amy Sussman/Invision for Purina ONE/AP Images)

Scottish Fold cat is displayed during a cat exhibition in Bishkek, Kyrgyzstan, 26 November 2017. Cats owners from Kyrgyzstan and Kazakhstan gathered in Bishkek to show their pets. (Photo by Igor Kovalenko/EPA/EFE/Rex Features/Shutterstock)

Darlene Eddy packages up a chocolate Easter bunny that she made in her store Amazing Chocolates on March 28, 2013 in Hollywood, Florida. As Easter Sunday approaches chocolatiers are busy manufacturing many different types of delights for the holiday when Americans spend roughly $1.9 billion on Easter candy, second only to Halloween in candy consumption. Around ninety million chocolate Easter bunnies are produced each year, from white to dark chocolate, and with an unlimited varieties of styles. (Photo by Joe Raedle)

Japanese embroidery artist Hiroko Kubota was in the process of making custom sized clothes for her smaller-framed son when he made a small request: could some of the shirts have cats on them? Kubota explains her son was somewhat obsessed with cats and had collected a small library of adorable images found around the web.

A cat jumps from a shelf to catch a light beam at the “Kis-Kis” Cat Cafe in the Siberian city of Krasnoyarsk, Russia, July 6, 2015. A local animals rights group founded the shelter for dozen of homeless cats and combined it with the cafe, where visitors can communicate with animals for hourly fee in addition to drinks, table games, books and WI-FI. (Photo by Ilya Naymushin/Reuters)

Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

Cat-Friend vs Dog-Friend, Two Humans Acting Like House Pets