Dogs as Pets and Pests: Global Patterns of Canine Abundance, Activity, and Health

Synopsis

Dogs (Canis familiaris) were the first domesticated species and, at an estimated population of 1 billion individuals, are globally ubiquitous today. Describing the tremendous morphometric diversity and evolutionary origins of dogs is a scientific endeavor that predates Darwin, yet our interdisciplinary understanding of the species is just beginning. Here, I present global trends in dog abundance, activity, and health. While the human–dog relationship has for millennia been close, it is also complicated. As pets, companion dogs are often treated as family members and constitute the largest sector of the ever-growing >$200 billion USD global pet care industry. As pests, free-roaming dogs are an emerging threat to native species via both predation and nonconsumptive effects (e.g., disturbance, competition for resources, and hybridization). Furthermore, I briefly discuss mounting evidence of dogs as not only infectious disease reservoirs but also as bridges for the transmission of pathogens between wild animals and humans in zoonotic spillover events, triggering intensive dog population management strategies such as culling. Dog mobility across the urban-wildland interface is an important driver for this and other adverse effects of canines on wildlife populations and is an active topic of disease ecologists and conservation biologists. Other canine scientists, including veterinary clinicians and physiologists, study more mechanistic aspects of dog mobility: the comparative kinetics, kinematics, and energetics of dog locomotor health. I outline the prevalent methodological approaches and breed-specific findings within dog activity and health research, then conclude by recognizing promising technologies that are bridging disciplinary gaps in canine science.

Uniqueness and global abundance of dogs

In a broad biological context, dogs are exceptional in many ways; they are the earliest known domestic organisms (Clutton-Brock 2012) yet remain the only domesticated large carnivore. Furthermore, at a population of approximately 1 billion individuals (Gompper 2014a), dogs are the most globally widespread and abundant carnivore (Vanak and Gompper 2009). For context, worldwide there are approximately as many dogs as the combined human populations of the third to sixth most populous countries (United States Indonesia, Pakistan, and Nigeria). Our canine companions are the most morphologically diverse mammalian species (Wayne 1986a, 1986b; Boyko et al. 2010) and present seemingly limitless phenotypic variation. This heterogeneity is the result of strong but evolutionarily recent artificial selective pressures on the basis of physical appearance, morphological functionality, and behavior or temperament (Worboys et al. 2018). Within the single species, dog breeds span two orders of magnitude in both body mass (a 44-fold difference; Jimenez 2016) and life expectancy (Kraus et al. 2013), and for these and many other reasons are being increasingly accepted as an interdisciplinary biological model organism (Bryce et al. 2021).

Despite the closeness of dog–human relationship over millennia, our association with canines is also complex. In much of the developed world, dogs are loved as pets; in many developing nations, dogs are loathed as scavenging, disease-spreading vermin. In India and elsewhere, dog aversion as a socio-cultural phenomenon has ancient roots (Debroy 2008). While biting free-ranging dogs can be a significant disease burden (discussed below), dogs are typically submissive in direct interactions with humans (Majumder et al. 2014) and their degree of sociability varies with human movement in urban areas (Bhattacharjee et al. 2021). The perception of dogs by various people groups is often geographically, historically, and culturally nuanced (Serpell 2016). Religion, too, can play a large role in human attitudes toward dogs. For example, Herzog (2019) found that predominantly Islamic nations, which tend to view dogs as unclean, had only one-third of the dog densities of other nations of comparable wealth. Global variation of opinions (and therefore treatment) of dogs is related to the nature and degree of association between dogs and people. The narrow Western construct of “dog” (as in owned pet dog) may be misleading as dogs exist under a broad continuum of human control, and pet dogs make up only a small portion of the global dog population. In fact, free-roaming dogs (those that are not permanently restrained or under human control, whether owned or unowned) are thought to account for roughly three-quarters of the approximately billion dogs on the planet (Hughes and Macdonald 2013; Kartal and Rowan 2018; Smith et al. 2019), although their mobility makes estimation difficult.

Dogs are now ubiquitous; they are found almost everywhere where humans exist and many places where humans are absent (Gompper 2014a). Dog prevalence estimates exist for approximately half (82) of the world’s countries, and the global per-capita average of 130 dogs for every 1000 people varies considerably, even among neighboring countries (Sykes et al. 2020; A. Rowan, personal communication, Fig. 1). Increasing pet ownership, particularly of dogs, is a worldwide phenomenon in spite of most dogs being-free roaming. One online survey of over 27,000 adults across 22 countries reported that one-third of households owned at least one dog, that dog ownership was slightly (but insignificantly) higher in females than males, and that dog ownership rates were highest in Central and South America (GfK 2016). Pet ownership has more than tripled since the 1970s, and today two-thirds of US households own a pet (APPA 2020a). Dogs continue to dominate in pet popularity; a conservative estimate is that over 38% of American households own at least one dog—the highest ownership rate sinceAmerican Veterinary Medical Association (AVMA) began measuring it in 1982 (AVMA 2018; Brulliard and Clement 2019) and among the highest per-capita ownership rates in the world (Herzog 2019). All told, the United States is home to over 77 million dogs (up 10% from 2011, although estimates vary considerably; Herzog and Rowan 2019), with shelter and rescue groups as the largest constituents (AVMA 2018). Dog ownership is expected to continue expanding fastest in developing countries where rising living standards and more discretionary income afford it (Tahir 2017; Sykes et al. 2020).

Fig. 1

Approximate global per-capita dog population distribution. Grayscale shades (#1–6) correspond to per-capita total dog densities (pet + free-ranging dogs/1000 people) and are based on data from Sykes et al. (2020) and Andrew Rowan, personal communication. Using available estimates, the global per-capita dog average is 130 dogs/1000 people (corresponding to shade #3).

Drivers of canine success

There are two canine characteristics facilitating their global success: their proximity to humans and their mobility across the urban-wildland interface (Fig. 2). First, the proximity in both space and time that dogs share with humans is unprecedented in the animal kingdom (Clutton-Brock 2012). This bond extends farther back into evolutionary time than it does with any other domesticated species. As a conservative minimum, the close human–canine bond dates at least 14,000 years before present (ybp) according to archeological evidence of the earliest definitive dog-like remains unearthed in co-burial sites with humans in present-day Germany (Janssens et al. 2018). By this time, dogs were distinct from wolves, and closely associated with humans or sites used by humans. By ∼1400 ybp, dogs had dispersed with humans to the extremes of every habitable continent (Larson et al. 2012), and to remote oceanic islands even earlier (Rick et al. 2008; Greig et al. 2018). Today, much of the developed world perceives dogs as partners and working companions for a variety of life’s activities, including hunting, law enforcement, guarding, guiding and assisting the disabled, load-pulling, military activities, search and rescue operations, and even therapeutic roles in clinical settings. Pet dogs function as companions and even family members (e.g., only 1% of dog-owning Americans consider their dog “property,” AVMA 2018) and people increasingly refer to themselves as “guardians,” “caregivers,” or “handlers” rather than dog “owners” (Hart and Yamamoto 2016). As companion animals, it can be argued that the human–canine bond could not become much stronger or closer; over half of American dog-owning households reported co-sleeping with their dog(s) (Rowan and Kartal 2018), despite more disruptions to human sleep (Patel et al. 2017; Smith et al. 2018; Hoffman et al. 2020). Similar prevalence of co-sleeping with dogs is reported throughout Australia (Thompson and Smith 2014) and elsewhere. Furthermore, of all domesticated species, only dogs (and cats) require no physical barriers (e.g., cages, fences, and tethers) to enforce their close association with humans (Serpell 2016). This may, be due, in part, to dogs’ impressive social cognition which is also present in their wild progenitor, the gray wolf (Bensky et al. 2013; Miklósi 2014; Arden et al. 2016). For example, social learning capacity and the ability of both species to use other animals’ behavior as a cue is enhanced in these canids compared with other social hunters or carnivorans, respectively (Lea and Osthaus 2018). Furthermore, dogs’ social plasticity may have been key to their successful domestication and ongoing reinforcement of the human–dog bond (Udell and Brubaker 2016; Sipple et al. 2021, this issue).

Fig.2

Proximity to humans and mobility across the urban-wildland interface as key drivers facilitating the global abundance and distribution of dogs. As pets and working animals with whom we share a close bond, dogs assist humans in completing tasks while providing numerous benefits to our health and well-being. Conversely, free-roaming dogs adversely impact wildlife populations through a number of direct and indirect ecological effects and can play detrimental roles as reservoirs and vectors of pathogens, even facilitating parasitic transmission between humans and wildlife (i.e., zoonotic diseases). Figure created using Mind the Graph Illustrations (www.mindthegraph.com).

Second, the mobility of dogs enables their successful worldwide proliferation. One key factor for dogs’ mobility is their underlying athletic capacity (see Davis 2021). Both wild and domestic members of the family Canidae are well-recognized for the cursorial (i.e., highly aerobic and mobile) lifestyles afforded by elongated limbs and digitigrade locomotion (Van Valkenburgh 1987; Boyd 2020). In dogs, this is best exemplified by the performance capacity (e.g., speed, endurance) of several highly trained breeds (Amanat et al. 2020). Greyhounds, for instance, have been strongly selected since at least Egyptian times for their agility and speed; greyhounds can reach velocities in excess of 62 km/h during races (Usherwood and Wilson 2005; Granatosky 2019). In contrast, sled dogs are capable of maintaining more moderate speeds for extremely long durations, even while pulling loads. Through rigorous selection and training, Alaskan sled dogs exhibit the highest sustained metabolic rates in the animal kingdom (Hinchcliff et al. 1997). Likewise, Greenland sled dogs can trot at ∼9 km/h for 8–10 h each day for 2–3 days, covering 60–80 km daily over rough terrain (Gerth et al. 2010). Although the extremes of canine performance are characterized by heavily “engineered” breeds, free-roaming dogs not under human selection are capable of similar feats of athleticism. For example, stray dogs Cactus and Gobi each voluntarily kept pace with racing ultrarunners in >30°C arid heat for hundreds of kilometers in the Marathon des Sables and Gobi Desert Run, respectively (Halsey and Bryce 2021).

Another key factor associated with dog mobility across landscapes is their adaptability. Free-roaming dogs can cover large areas and move readily across complex gradients of human influence (Sparkes et al. 2014; McNeill et al. 2016; Sen Majumder et al. 2016), from urban centers to relatively unperturbed landscapes and back (Young et al. 2011; Gompper 2014b). This is in part facilitated by their flexible sociality (solitary, pack-forming, or even hybridized with native canid species; Leonard et al. 2014) as well as dietary breadth (Ritchie et al. 2014). Dogs in urban environments tend to exhibit limited ranging patterns while subsisting on a human-dependent diet, but more rural dogs travel farther and are less reliant on anthropogenic food subsidies (Vanak and Gompper 2009). As such, they can adversely affect native wildlife populations through not only disturbance (Weston and Stankowich 2014) but also predation (Ritchie et al. 2014). A more in-depth discussion of canine impacts on wildlife is given by Gompper (2021, this issue). When including pet dogs, the global canine population has a substantial “ecological paw print” in terms of both resource requirements and feces production (Martens et al. 2019). Compared to a human, through their diet the average dog constitutes at least one-fourth of the environmental impacts from animal production in terms of the use of land, water, fossil fuels, phosphate, and biocides (Gompper 2014a; Okin 2017). While both free-roaming and pet dogs are adaptable consumers, the aggregate costs to the environment are considerable given their worldwide abundance and distribution.

Trends in canine health

No discussion of canine health would be complete without a brief historical overview of humans caring for their domesticated animals. What would eventually become known as veterinary practice was undertaken by 5000 ybp for various species in the ancient civilizations of China, Mesopotamia, Egypt, and India centuries before it arrived in Greece, Rome, and eventually Europe (Mark 2020). Nevertheless, the comprehensive, empirical approaches and enduring works of the Greeks (namely Hippocrates) and later the Romans (namely Galen and Vegetius) earned these three designations as the “fathers of veterinary medicine.” Each maintained the rather unconventional assertion that illness in both humans and animals was the result of naturally occurring causes (e.g., environmental factors, diet, and lifestyle) rather than divine discipline, and espoused controlled procedures, rather than incantations, to improve health. For nearly the next millennium (c. 5th to14th centuries), the Medieval church forbade animal dissections and autopsies, and confiscated or destroyed much of the early literature on veterinary medicine. The field was all but eliminated, and it was not until the Enlightenment of the 18th century that veterinary medicine once again gained attention and momentum. French veterinary surgeon Claude Bourgelat founded the first veterinary research institute in 1762, in response to massive cattle rinderpest mortalities during the plague. Bourgelat’s students made such significant progress in veterinary research, diagnosis, and treatment that the veterinary institute concept was quickly propagated elsewhere in Europe, and 90 years later, the Veterinary College of Philadelphia became the first of its kind in the United States (Mark 2020). Today, there are over 800 recognized schools of veterinary medicine in nearly 100 countries, many of which are certified by the Education Commission for Foreign Veterinary Graduates (AVMA 2020).

In much of the world, there has never been greater access to veterinary care for dogs. In the United States alone, there are at least 26,000 small animal veterinary practices (Downing 2014), and many of these clinics specialize almost exclusively in companion animal care. North America, and the United States in particular, is by far the largest segment (∼45%) of the $91 billion USD global veterinary services market (2019 data, The Business Research Company 2020). Unsurprisingly, a correlation exists between the degree of human–dog bonding and pet spending. Households that consider dogs to be family members averaged three veterinary visits in 2006, for example, in comparison with 2.2 visits for households that consider dogs to be pets or companions, and 1.1 visits for households that consider dogs to be property (Burns 2008). Western Europe and Asia Pacific are second and third in global veterinary market share, both worth about half of America’s segment. However, the growth rate of Asia Pacific’s market recently surpassed that of both North America’s and Western Europe’s. China is experiencing a significant increase in pet ownership, and associated demand for companion animal veterinary services among its growing urban population. Nearly 10% of families in China’s tier-1 and tier-2 cities now own pets (Thibaud 2017).

With the exception of the pandemic-induced downturn of 2020, the global veterinary services industry is keeping pace (>5% compound annual growth rate, CAGR) with the $223 billion USD worldwide pet care industry (2019 data, Ugalmugle and Swain 2020). This is driven by numerous factors, including the growing global pet population, increasing adoption of big data among veterinarians to assess, diagnose, and advise treatment for both pets and livestock (VanderWaal et al. 2017; Perez 2018), pet humanization among millennials and within the growing global urban population, and social media-driven increased awareness of animal welfare needs across the five physical/functional domains (nutrition, environment, health, behavior, and mental state; The Business Research Company 2018; Mellor et al. 2020).

Despite increased availability of veterinary services, high costs associated with specialized clinical equipment, licenses, and trained personnel are decreasing affordability for pet owners. In the United States and other developed countries, recent decreasing trends in veterinary clinic visits by pet and livestock owners suggest such visits are becoming cost-prohibitive, especially in light of readily available of online pet health information (Felsted 2011). One survey revealed that 43% of US dog owners rely on online information for their canine’s health (APPA 2020b). Similarly, the global pet insurance market is projected to grow at 16.3% CAGR through 2028 (Grand View Research 2019) as high veterinary healthcare costs, growing per-capita income, and increasing availability of online pet health information are driving a global trend by owners to purchase canine insurance (APPA 2020a). Nevertheless, only ∼2% of American pets are insured (Jenks 2017), and nearly 85% of these are dogs (NAPHIA 2020). At the other extreme, ∼90% of dogs in Sweden have insurance coverage (Kelly 2019).

Like humans, dogs may experience a wide variety of medical conditions or diseases over the course of their lives. The risk factors for these depend not only on individual age, sex, and weight but also breed. A growing body of veterinary and primary research literature describes the impact of various risk factors on canine conditions. Several national-scale meta-analyses reveal the utility of electronic veterinary records to this end (e.g., O’Neill et al. 2014; Kim et al. 2018). At an even broader scale, disease susceptibility patterns exist from studying the underlying genetic architecture associated with human-relevant diseases in domestic dogs (e.g., Ostrander et al. 2019). Among pet dogs in particular, diabetes mellitus, urinary problems, obesity, and musculoskeletal conditions like osteoarthritis (OA) are widespread. Canine obesity and OA are often linked. Data from over 1000 general practice pet hospitals revealed that overweight dogs (>10–20% heavier than ideal weight; Brooks et al. 2014) are 2.3 times more likely to be diagnosed with OA (Banfield Pet Hospital 2019). In turn, dogs with OA are 1.7 times more likely to also be overweight. Like obesity in humans, canine obesity is a pandemic even in developing nations (Mao et al. 2013; Ward et al. 2019). In one study, 51% of >1.9 million adult dogs seen at US pet clinics were classified as overweight, and <10% were successful at losing weight, regardless of their age (Banfield Pet Hospital 2020). Canine obesity and the numerous clinical conditions that arise from it not only adversely affect dog health, but also welfare and quality of life (German et al. 2012; Yam et al. 2016).

Beyond the serious health effects associated with the aforementioned medical conditions, dogs are susceptible to a host of viral and bacterial diseases. Common canine bacterial infections include tracheobronchitis, Leptospira spp., Salmonella spp., and Bordetella spp. Prevalent viral infections include coronavirus, distemper, hepatitis, influenza, and parainfluenza, and parvovirus. With their generalist diet, wide-ranging mobility, and ubiquitous proximity to humans, dogs also serve as zoonotic disease reservoirs and facilitate the movement of over 60 parasitic species between wild animals and people (Macpherson 2005; Knobel et al. 2014; Ghasemzadeh and Namazi 2015; Gompper 2021, this issue). Fortunately, there is increasing recognition of the link between animal diseases, public health, and the environment (e.g., Takashima and Day 2014; De Giusti et al. 2019). Rabies is one dog-mediated zoonosis of public health concern worldwide. Rabies is estimated to cause nearly 60,000 human deaths each year across 150 countries (Fahrion et al. 2016). Tragically, half of these cases are attributable to children under 15. Widespread underreporting and estimate uncertainty suggest that this number is a gross underestimate of the true burden of disease. Nearly all (99%) of rabies cases are dog-mediated, and 95% of cases occur in rural, poor populations in Africa and Asia. For this and other pressing concerns (e.g., predation of wildlife species, hybridization with native canid species), free-roaming dog populations are managed using a variety of methods including culling, sheltering, and capture–neuter–vaccinate–release programs (reviewed in Smith et al. 2019, further discussed in Gompper 2021, this issue). As a result, humans can be major source of early life mortality in some free-ranging dog populations (Paul et al. 2016).

Although free-roaming dogs can exert a suite of adverse effects on people and wildlife, companion animal dogs have been shown to enhance human mental, emotional, and physical health (Wells 2007; Dotson and Hyatt 2008; Stanley 2009; Hodgson and Darling 2011; McCardle et al. 2011; Beetz et al. 2012; Takashima and Day 2014; Casciotti and Zuckerman 2016; but see Herzog 2011, 2020; Rodriguez et al. 2020). To name a few of the myriad benefits of the so-called “pet effect,” dog owners and people with frequent canine contact have lower stress levels (Nagengast et al. 1997; Aydin et al. 2012; Barker et al. 2012; Tournier et al. 2017), reduced risk of heart disease (Allen et al. 2002; Levine et al. 2013; Schreiner 2016), lower blood pressure (Allen et al. 2001; Wright et al. 2007) and cholesterol levels (Hodgson et al. 2015), strengthened immune systems (Gern et al. 2004; Wegienka et al. 2011; Schreiner 2016), make fewer annual doctor visits (Headey and Grabka 2007), take fewer sick days off from work (Headey et al. 2008), enjoy improved workplace wellness and productivity (Wells and Perrine 2001; Wilkin et al. 2016), experience improved social connections (McNicholas and Collis 2000; Wood et al. 2015) and support (McConnell et al. 2011; Brooks et al. 2016, 2018), and decreased levels of loneliness (Antonacopoulos 2017) and depression (Crowley-Robinson et al. 1996; Clark Cline 2010). One study conservatively estimated the annual American healthcare cost savings associated with pet ownership (i.e., quantified as fewer medical office visits by pet owners and reduced incidence of obesity among dog owners who frequently walk their pets) at over $11.7 billion (Clower and Neaves 2015). However, numerous studies suggest surprisingly little to no effect of dog ownership status with increased exercise or decreased incidence of obesity (e.g., Cutt et al. 2007; Gillum and Obisesan 2010; Westgarth et al. 2012; Brown and Jensen 2020; Koohsari et al. 2020; Miyake et al. 2020).

Important limitations of many “pet effect” studies include reliance on self-reported data (which is subject to recall bias—the difficulty subjects have accurately remembering and reporting past events or psychosocial states; e.g., Prince et al. 2008) and various methodological weaknesses. For example, a systematic review on the psychosocial effects of assistance dogs for individuals with physical disabilities found that for nearly 70% of the comparisons made across 27 included studies, there was no evidence of any impact of assistance dogs on the mental health or well-being of their owners (Rodriguez et al. 2020). Inadequate reporting, failure to account for moderating or confounding variables, and positive publication bias are common phenomenon plaguing the social and behavioral science literature on the “pet effect,” and more systematic, reproducible studies are needed to decipher trends that may exist (Herzog 2020).

Dog activity and locomotor health

Canine athleticism and the elegant diversity of dog movement have captivated the imaginations of artists, engineers, and scientists for centuries. Muybridge’s (1887) pioneering and enlightening work in sequential photographic studies of animal movement, including dogs, set the stage for further detailed investigations (Gill et al. 2020). Since that time, breed-specific movement has been highly selected and trained for among dog breeders seeking to exhibit the prowess of their purebred at conformation events (i.e., dog shows). Seminal works by Elliott (1973), Brown (1986) and others showcased canine gait variation across breeds and paved the way for even more rigorous experimental endeavors to quantify the distinctions and their functional importance. Both veterinary clinicians and researchers utilize controlled laboratory settings for such work. On such investigation, the Jenna Study is perhaps the most comprehensive and innovative analysis to date (Fischer and Lilje 2011). Over 300 dogs (10 representatives each of 32 breeds) participated in high-speed marker-based movement analysis and biplanar X-ray videography trials to study the influence of body shape and weight (>25-fold weight spectrum) on canine locomotion. Unlike gait analysis studies focused on characterizing orthopedic or neuromuscular pathologies (e.g., Zink 2013; Carr and Dycus 2016), the Jena Study described the detailed motion sequences of healthy adult dogs. Despite large morphological disparity, surprising uniformity was found in the relative proportions of the fore and hindlimbs across breeds. For example, humerus length was found to be 27 ± 0.7% of anatomical limb length regardless of breed and is thought to contribute to the striking similarity in the underlying motion of canine bones, muscles, and connective tissues (Fischer and Lilje 2011).

Traditionally, dog activity locomotor health has been explored through three primary methodological disciplines: kinetics, kinematics, and comparative energetics. A historical emphasis in canine veterinary medicine has been the kinetic analysis: the study of forces occurring during motion (reviewed in Sandberg et al. 2020). By quantifying ground reaction forces (GRFs) transmitted through a given limb, clinicians can objectively measure both musculoskeletal conditions and therapeutic modalities. GRFs reveal limb-specific patterns of weight bearing in dogs and therefore afford means to evaluate total limb function. For joint-specific evaluation within a limb of interest, kinematic analyses must be applied. Kinematic data provide insight into joint range of motion, angular and segmental velocities of limb components, and basic biomechanics such as stride length and frequency as functions of dog speed. In recent years, 2D and 3D video motion capture analyses have greatly aided the collection of such data and our understanding of in-motion limb functionality (Kim et al. 2008; Kearney et al. 2020). Finally, the study of canine energetics seeks to not only quantify the gait-specific metabolic rates of various breeds, but also compare domestic dogs to their wild progenitor, the gray wolf (Canis lupus) and other members of Family Canidae. Both wild and domestic canids are widely recognized as endurance athletes within the animal kingdom (Weibel et al. 1987; see Davis 2021). Wolves, dogs, foxes, and dogs exhibit aerobic capacities that are approximately three times greater than those of equivalently-sized mammals (Weibel et al. 1983), facilitating their ability to run for extended periods at sustained speeds without becoming anaerobic (Okarma and Koteja 1987). Bryce and Williams (2017) found that some ancient-lineage dogs (including northern breed “sled dogs”) exhibit comparable standing and running postures to C. lupus, which may contribute to their locomotor economy relative to other breeds.

Increasingly, methods for monitoring the behaviors and activity patterns of dogs are being applied outside research or clinical laboratory contexts (e.g., Hoffman et al. 2019). One emerging trend is the use of commercially available wireless health monitoring technology (“wearables”) such as smart collars for dogs. Wearables are revolutionizing our collective understanding of canines through collection of in situ location data and vital health parameters (e.g., body temperature, heart rate, respiration rate, pH, and locomotor gait and activity levels; Jukan et al. 2017; Cotur et al. 2020). Most commonly, wearables are simple collar-attached inertial measurement units (IMUs, such as triaxial accelerometers) marketed to monitor and inform dog owners of welfare needs, including daily exercise and feeding regimes, to optimize their pet’s health (Ladha et al. 2013; Chambers et al. 2020). Several makers of pet wearables have even made canine activity and health insights from their global user base freely available (e.g., FitBark Explore, Pet Insight Discover). Wearables are forecast to grow at an astounding 14% CAGR in the next few years as their pet health monitoring benefits become more globally recognized (Harrop et al. 2017; Grand View Research 2020). Dog health insights from IMUs such as patterns of increased scratching or decreased activity can also aid in the detection and treatment of canine neuropathic or orthopedic conditions (Barthélémy et al. 2009; Carr and Dycus 2016). Wearable data is just one of many “big data” sensor streams being progressively incorporated into veterinary care (VanderWaal et al. 2017; HealthforAnimals 2018; Perez 2018).

Conclusion

Our long, shared evolutionary trajectory with dogs combined with several inherent canine characteristics (e.g., athletic physiology, flexible sociality, and generalist diet) have contributed to the longstanding ubiquitous distribution of dogs as well as their ability to thrive with or without direct human care. If history is any indicator, the worldwide dog population will continue to grow and canines will increasingly permeate the human experience as pets, free-roaming conspecifics, and in many places both. The reciprocal benefits of companionship for both dogs and humans are being experienced by broader demographics, and enhanced veterinary access and standard of care rivals that of human medical care in some locales. Going forward, dogs are poised to remain near the forefront of not only interdisciplinary biological research (Bryce et al. 2021), but also technological innovations and medical advancements that are mutually beneficial to dogs and humans alike.

Funding

Support for this article's host symposium “Biology's best friend: Bridging the gaps to advance canine science” at SICB 2021 came from the Company of Biologists and the Society for Integrative and Comparative Biology.

Conflict of interest

None to declare.

From the Symposium “Biology’s best friend: Bridging disciplinary gaps to advance canine science” presented at the Annual Meeting of the Society for Integrative and Comparative Biology, Virtual meeting, January 7, 2021.