September 17, 2008, Updated September 13, 2012

Cats are from Mars and dogs are from Venus. Or the other way around. Everyone knows that they don’t get along. But everyone also knows a story about the cat that adopted the puppy or the dog that cared for the kitten. Now, new research at Tel Aviv University, the first of its kind, has explored the phenomenon of harmonious interspecies relations and developed a model that, by extension, could be used by humans too.

Over thousands of years of domestication, dogs (Canis familiaris) and cats (Felis catus) have undergone genetic changes to adapt to the human environment. Both species are found around the world and it quite common to find homes with the two living side by side.

Nevertheless, there is widespread belief among humans that inter-species communication between dogs and cats is problematic, because of their separate evolutionary development and differing social structures. Consequently, many people considering possible adoption of both species are concerned about their ability to get along.

The good news, according to the study, is that the earlier the age of first encounter between the two, the better the understanding. If the cat is adopted before the dog and if they are introduced when still young – less than six months for kittens, 12 months for dogs – the probability is high that the two pets will get along. Results from the research were recently reported in the journal Applied Animal Behaviour Science.

“You barkin’ at me?”

The findings also suggested that the majority of the dogs and cats studied were able to understand the meaning of a particular body language displayed by one species that has an opposite meaning for the other species.

“This is the first time anyone has done scientific research on pets living in the same home,” says Prof. Joseph Terkel, of the Department of Zoology at Tel Aviv University. “It’s especially relevant to the one-third of Americans who own a pet and are thinking about adopting a second one of the opposite species.”

After interviewing almost 200 pet owners who own both a cat and a dog, then videotaping and analyzing the animals’ behavior, TAU researchers concluded that cats and dogs can cohabitate happily if certain conditions are met. Terkel and graduate student Neta-li Feuerstein found that two-thirds of the homes they surveyed reported a positive relationship between their cat and dog.

However, in 25% of homes, there was a reported indifference between the cat and dog, while aggression and fighting were observed in 10% of the homes.

One reason given by the researchers for the fighting might be crossed inter-species signals. As with people, cats and dogs are not always able to read each other’s body cues. For example, cats purr when happy, while dog wag their tails. Cats tend to lash their tails about when angry, while dogs growl and arch their backs. Eye contact is another area for miscommunication: a cat’s averted head signals aggression, while the same head position in dogs signals submission.

In the harmonious homes, Terkel observed a surprising behavior. “We found that cats and dogs are learning how to talk each other’s language. It was a surprise that cats can learn how to talk ‘Dog’ and vice versa.”

A model for people, too

The most hopeful aspect of the research, as far as humans are concerned, is that the cats and dogs living in harmonious homes appeared to have evolved beyond their instincts, learning to read each other’s body signals.

The researchers observed that, once familiar with each others’ presence and body language, cats and dogs could play together, greet each other nose-to-nose – even share the same couch and sleep together. They could also share the same water bowl and in some cases groom one another.

The results suggest that the two species may have more in common than was previously suspected. By extension, the Tel Aviv University research on cats and dogs implies that even so-called natural-born human enemies can find ways to live together. “If cats and dogs can learn to get along,” said Terkel, “surely people have a good chance.”

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