‘Animal Odd Couple’: Deer and Great Dane are best friends

We expect cross-species friendship in animated films — "Dumbo," "Bambi" and "The Fox and the Hound," are just three examples of many — but in the non-cartoon world, they're still fascinating to observe.

PBS's "Animal Odd Couples" documentary premiered on Wednesday. Among its featured animal pairings is Kate, a Great Dane, and the abandoned fawn she adopted, Pippin.

Footage of the adorable unlikely duo has gone viral.

"When they greet each other, I've never seen anything like it. It's not a deer greeting a deer. It's not a dog greeting a dog. It's definitely something that they have between the two of them," Kate's owner, Isobel Springett, said of the best friends.

Their friendship mirrors other headline-making cross-species buddies, like Susie the rescue dog and her pig friend and the inseparable Tarra the elephant and Bella the dog.

"These friendships, unlikely friendships in a good number of cases, show that emotions including joy, love, empathy, compassion, kindness, and grief can readily be shared by improbable friends including predators and prey such as a cat and a bird, a snake and a hamster, and a lioness and a baby oryx," writes Marc Bekoff, Ph.D., for Psychology Today. "And, of course, the best examples of emotions being shared between different species are those close and enduring relationships we humans form with the companion animals with whom we share our homes and with those nonhumans with whom we work closely to rehabilitate when they're in need."

PBS explains what "Animal Odd Couples" attempts to explore:

"Each interspecies pair challenges the conventional wisdom that humans are the only species capable of feeling compassion and forming long-lasting friendships.Animal behavior experts weigh in with their opinions, and animal caretakers share their personal experiences with cross-species relationships in this compelling tale of unlikely animal couples."

Have you witnessed a cross-species friendship?