ResearchBehavioral effects of auditory stimulation on kenneled dogs
Introduction
Countless dogs are kenneled, either short term or long term, for a variety of reasons (Hubrecht and Turner, 1998). Some dogs are kenneled for short-term boarding, whereas others, including strays or those relinquished by owners, are kenneled in a rescue setting for varying amounts of time, some indefinitely. Other dogs are bred as laboratory animals and spend their entire lives in a kennel environment (Wells, 2004).
The kennel environment, even for short periods, is a potential psychogenic stressor for most dogs owing to its novel surroundings and separation from social attachment figures (Beerda et al., 2000, Hennessy et al., 2002, Pullen et al., 2010). A kennel is spatially and socially restrictive, and as a result, many dogs show signs of acute stress when housed in kennels (Hiby et al., 2006, Rooney et al., 2007). Social isolation or restriction, a major stressor for many dogs, can lead to the development of both physiological and behavioral problems (Bergamasco et al., 2010, Hubrecht and Turner, 1998).
Continual stress, and resultant anxiety, is undesirable for both ethical and physiological reasons. Stress in animals has both short-term and long-term effects on health and life span (McEwen, 2005). A recent study (Dreschel, 2010) found that increased stress in dogs is correlated with shorter life spans and increased skin disorders. Anxiety, demonstrated through physical and behavioral manifestations, is a growing welfare concern in veterinary medicine (Overall and Dyer, 2005), and as a result, there has been increasing awareness and concern for the welfare of kenneled dogs and the development of potential strategies to improve their environment (Bergamasco et al., 2010).
The primary means that have been used to assess stress are physiological measures and behavioral observations (Bergamasco et al., 2010). Physiological measures to assess stress include immune functions, heart rate, sympathetic nervous system activation monitoring, and hormonal indicators (Bergamasco et al., 2010, Rooney et al., 2007). Behavioral observations include lowered body posture, panting, vocalizing, paw-lifting, body shaking, and repetitive or stereotypic behaviors (pp. 49-62, Beerda et al., 2000, Beerda and Schilder, 1997; Hetts et al., 1992).
One growing area of research pertaining to the welfare of kenneled dogs is the idea of environmental enrichment. Environmental enrichment can be defined as any technique designed to improve the functioning of an animal through modifications to the environment (Newberry, 1995). The goals of environmental enrichment for kenneled animals include helping these animals to handle the inherent challenges in kennel environments (i.e., lack of control and unpredictability), encouraging more species-specific behaviors, and reducing abnormal or stereotypic behaviors (Wells, 2009, Young, 2003). One area of environmental enrichment that has started to receive more attention is that of sensory stimulation. This stimulus type is presented to trigger one or more senses (i.e., vision, smell, and/or hearing) as a method of environmental enrichment. This line of inquiry, however, is still new and sporadic (Wells, 2009), and conclusive evidence on effectiveness is still unclear.
Auditory stimulation is one aspect of sensory stimulation that has received increased attention in current years with a variety of species. Listening to music has been found to be a mood-regulatory behavior (Saarikallio and Erkkilä, 2007), and several studies involving humans have found mood regulation and emotional management to be among the most important reasons for music consumption (North et al., 2000; Saarikallio and Erkkila, 2007; Sloboda, 1992, Wells and Hakanen, 1991).
Numerous studies on humans have found listening to relaxing or classical music to be beneficial in a variety of areas (Bechtold et al., 2009), including a decrease in anxiety (Dubois et al., 1995), increase in prosocial behaviors (Gueguen et al., 2010), improvement in satisfaction with medical procedures, decrease in blood pressure and heart rate (Chlan et al., 2000), increased tolerance for uncomfortable procedures, reduction in pain perception (Bampton and Draper, 1997, Nelson et al., 2008), and decreased need for sedative medications (Nelson et al., 2008, Schiemann et al., 2002).
Within other nonmedical settings, music has been found to positively affect various behaviors (Magnini and Parker, 2009), including the amount of time spent by customers in an establishment (Milliman, 1982, Milliman, 1986) and how much money people spend (Areni and Kim, 1993).
The recognition of the effect music can have on humans has generated interest in investigating the effect of music on other species. A limited number of studies have explored the effects of music on nonhuman animals. For example, classical music has been suggested to enhance the well-being of chickens (Gvaryahu et al., 1989), carp (Papoutsoglou et al., 2007), Asian elephants (Wells and Irwin, 2008), western lowland gorillas (Wells et al., 2006), and domestic dogs (Wells et al., 2002). Other types of auditory stimulation that have been studied include the effects of country music on cattle (Uetake et al., 1997, Wisniewski et al., 1977) and ponies (Houpt et al., 2000).
Exactly why music affects animal stress and behavior is not thoroughly understood.
Despite the uncertainty regarding what causes the positive effects seen with music, the fact that some studies have found that music can positively affect animal stress and behavior has stimulated the development of a growing number of music selections, created and marketed specifically to enhance companion animal well-being. Despite the growing popularity of music tailored toward dogs, there remains a dearth of studies to investigate these claims. The only study published in a peer-reviewed scientific journal to date that has investigated the effect of music on dogs was done by Wells et al. (2002). Given that the study by Wells et al. (2002) involved only 1 exposure to each type of auditory stimulation, further exploration of the effect of music on dogs was thought to be important. Therefore, the current study investigated the effect of auditory stimulation on activity, vocalization, and body shaking—a behavior suggestive of anxiety or nervousness.
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Material and method
The study was conducted within a building, in Northern Colorado, that housed both a dog shelter and boarding facility (a place where dogs are temporarily housed for a fee). The shelter had space for approximately 160 dogs. It consisted of 2 long runs, with kennels on each side of the concrete walkways. The kennels were rectangular concrete enclosures with a wire mesh front gate. The dogs were housed either singly or in pairs. Two populations of dogs were studied: dachshund rescue dogs and dogs
Results
A mixed model analysis of variance was used to control for multiple readings from the same dog and the fact that some dogs received more exposures to the auditory stimulus than other dogs, based on how long they were kenneled. The statistical significance level was accepted at P < 0.05. Because there was no significant interaction between auditory stimulus type and type of dog (i.e., rescue or boarding) or type of housing (singly or housed with other dogs) for any of the 3 categories of
Discussion
Both boarded and rescue dogs responded to all the classical music selections by sleeping more than during exposure to any other auditory stimulation type. The number of observations of silence was greatest during 1 classical selection (classical 2) and least during the control period (no music). These results are consistent with human studies, which have suggested that music can reduce agitation (Sung et al., 2008), promote sleep (de Niet et al., 2009), improve mood, and lower stress and
Conclusion
Results from this study suggest that auditory stimulation can affect kenneled dogs’ behaviors and stress levels, and therefore, auditory stimulation can be used to enhance the welfare of shelter dogs. The findings from this study have potential welfare implications for shelter dogs. As outlined in the American Veterinary Medical Association Animal Welfare Principles, “Procedures related to animal housing, management, care, and use should be continuously evaluated, and when indicated, refined or
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