Interrelationships of dogs (Canis familiaris) and cats (Felis catus L.) living under the same roof

Abstract

In the process of domestication, dogs (Canis familiaris) and cats (Felis catus) have undergone thousands of years of genetic changes that have adapted them to the human environment. Both species have acquired a global distribution and it has become quite common to find homes with the two living side by side. Nevertheless, there is widespread belief that interspecific communication between dogs and cats is problematic, stemming from their separate evolutionary development and different social structures. Consequently, many people considering possible adoption of both species are concerned about their ability to get along.

Interrelationships of dogs and cats living together were studied here in an attempt to determine the main factors influencing the type of relationship likely to develop between the two species. Two approaches were used: (1) a questionnaire completed by owners of both dog(s) and cat(s), which provided a broad database of the animals’ behaviors; and (2) observations carried out in participants’ homes on their dog–cat interactions. Two separate ethograms for dogs and cats served for analyses of their body language. The findings revealed the following: Both species showed a similar ability to establish a relatively amicable relationship with the other species; the animals’ gender had little influence on the nature of their interrelationship; and adoption of the cat prior to the dog appears to conduce to establishing an amicable relationship, as does their first encounter taking place at an early age (up to 6 months of age in cats and up to 1 year in dogs). The findings also suggest that the majority of these dogs and cats understood the particular body language displayed by one animal that has an opposite meaning for the other species; and that the earlier the age of first encounter between the two, the better this understanding. It can be concluded that exposure of both species at an early age to the presence of the other facilitates the learning of each other's body language, and the consequent establishment of an amicable relationship. A better understanding of the various factors that contribute to determining the two species’ relationship should not only improve the quality of life of these pets, but also reassure and encourage more people to adopt both cat and dog.

Introduction

The domestic dog (Canis familiaris) and the domestic cat (Felis catus L.) are the two most widely kept household pets. Both species have undergone thousands of years of genetic changes in adaptation to humankind and living in human surroundings. According to archaeological findings the domestic dog is the first species to have habituated to commensalism with humans, probably around 14,000 years ago (Nobis, 1979, in Clutton-Brock, 1999), though recent molecular genetic findings date the emergence of the dog to somewhere between 35,000 and 100,000 years ago (Vila and Savolainen, 1997, Savolainen et al., 2002). The dog's origin appears to be linked to the north-east Asian wolf (Canis lupus) (for review see Clutton-Brock, 1995, Vila and Savolainen, 1997). The domestic cat is probably descended directly from the African wild cat (Felis silvestris L.) (Bradshaw et al., 1999, Cameron-Beaumont et al., 2002). Though the Egyptians are often given credit for first domestication of the cat, about 4000 years ago, recent findings have suggested that the cat was actually domesticated some 9500 years ago in Cyprus (Vigne et al., 2004).

A major factor that affected the domestication process of both species was the presence of food resources within human settlements. It has been hypothesized that dogs originally associated with man without constraint, receiving in return for their company only the small remuneration of food (Budiansky, 1989). Dogs, as a highly social species, underwent a selection process by humans and as a result have long occupied a unique place in human society. Nowadays, in addition to their role as pets, dogs are used for a wide variety of practical or recreational purposes, ranging from guard dogs, guide dogs for the blind and explosives detection dogs, to serving as scent detectors for identification of breast and lung cancers (McCulloch et al., 2006). Regarding cats, these served man as controllers of vermin in times when the agricultural economy was based on grain, and in return they were provided with shelter and food. However, unlike dogs and other domesticated animals (such as cattle, horses, sheep and pigs), in which selective reproduction was applied in order to achieve various desired traits, no control was placed on cat reproduction or movement (Izawa and Doi, 1994). Accordingly, domestication has had less effect on the cat than on other domestic mammals, in both physiological and behavioral terms, and it is likely that cats are still at an earlier phase of domestication than dogs (Bradshaw, 1992, Bradshaw et al., 1999). Nevertheless, the cats’ primary role in human life has greatly changed over the course of domestication, from pest-controllers to companions, possibly due to their adaptability to living in a wide variety of environments, including apartments and small homes (Beaver, 1992).

Though both dogs and cats belong to the order Carnivora, whose members are renowned for their aggressive and efficient hunting abilities (Throrne, 1992), these two species differ greatly in their social behavior (Fox, 1971, Bradshaw and Brown, 2006). Unlike dogs and their closest relatives, which are social creatures that live and hunt as a pack, cats come from an entirely different group whose members are mostly solitary hunters and are considered to be asocial. Both species communicate via visual, olfactory and auditory channels as well as physical contact, and show a high ability for observational learning. Their visual communication methods are expressed mainly by means of body language in relation to dominance status, aggression and fear (For separate reviews on dogs and cats, see Serpell, 1995, Beaver, 1992). Although in many cases both dogs and cats employ a universal body language whose meaning among different mammals is generally similar and comprehensible, they also display a variety of signs that are unique to their particular species.

Raising dogs and cats under a shared roof is a comparatively new trend in Israel, and can be considered a direct result of the domestication process and of more recent changes in human urban lifestyles that have led to closer relationships with these two species.

There is a general belief that interspecific communication between dogs and cats is complicated (Beaver, 1992), stemming from their separate evolutionary development, their different domestication processes and the lack of an innate ability to understand each other's communications.

Although many studies have explored the relationships between human and dog as well as between human and cat (Mertens, 1991, Turner, 1991, Rooney et al., 2000, Adamelli et al., 2005, Miklosi et al., 2000, Miklosi et al., 2005), no studies, to our knowledge, have examined the nature of relationships between dogs and cats living in the same house, and their interactive behavior. Such studies could provide valuable information concerning development of the interspecific relationship and communicative behavior of the two species and expand our knowledge regarding the role of the social environment provided by humankind in their pets’ lives.

The objectives of this study were: to examine the nature of relationships between dogs and cats sharing the same living environment; to determine whether a mutual understanding of each other's body language exists; and to explore the main factors (e.g. age of adoption, adoption order, gender, neutering) that may influence the type of relationship that will develop between the two species.

Two main hypotheses were considered: (1) that an early age of adoption for both species is expected to play a pivotal role in the primary establishment of an amicable relationship between dog and cat. This is due to the socialization process that takes place in the “critical period” during the 3rd and 9th week of life in both dogs and cats (Scott and Fuller, 1965, Beaver, 1992); and (2) that if the first hypothesis proves correct, and an amicable relationship between the two species is established, then an accompanied learning of mutual body cues, reflected in a mutual understanding of each other's body language, would also be expected.