14 Nov
Image: © Juergen / Adobe Stock
Environmental enrichment involves the provision of stimuli to an animal’s environment in an attempt to improve its psychological and physiological welfare.
Sensory enrichment is a form of environmental enrichment where auditory, olfactory or visual stimuli are utilised. Sensory enrichment has applications in the management and housing of dogs. The use of auditory enrichment, such as classical music and audiobooks, is suggested to have positive behavioural effects in kennelled dogs by enhancing resting, and reducing vocalisations. However, use of heavy metal music should be avoided as it can increase barking and body-shaking, while pop music, psychoacoustically designed classical dog music and radio talk shows do not seem that effective at ameliorating dog stress.
In addition, the use of olfactory stimuli, such as lavender, coconut, vanilla, and ginger, have been found to reduce vocalisations and activity in dogs, suggestive of reduced stress. Visual enrichment, via use of televisions, decreased vocalisations and activity, but also seemed of relatively little interest to the dogs. In conclusion, auditory and olfactory enrichment seem to be effective, easily-applied and relatively inexpensive methods for enhancing dog welfare.
Environmental enrichment involves the provision of stimuli to an animal’s environment in an attempt to improve its psychological and physiological welfare (Newberry, 1995; Wells, 2009). One form of environmental enrichment that can be used in a range of contexts, including veterinary practices and animal shelters, is sensory enrichment.
Sensory enrichment involves the provision of auditory, olfactory or visual stimuli in an attempt to enhance animal welfare (Wells, 2009). Utilisation of sensory enrichment is valuable in the management and housing of dogs as it provides a straightforward, easily applied and, in many cases, relatively inexpensive form of enrichment.
A number of studies have examined the use of auditory enrichment in dogs.
Wells et al (2002) investigated the effects of five music types (classical, heavy metal, pop, human conversation, and no music control) on the behaviour of dogs (n=50) housed in a rescue shelter. They found that exposure to classical music induced greater frequencies of relaxation-like behaviour (such as reduced vocalisation; prolonged resting) compared to exposure to other genres, suggesting classical music held the potential to reduce stress-related behaviour.
This finding was supported by more recent research by Kogan et al (2012), which further evidenced the efficacy of classical music in enhancing sleeping and reducing vocalisations in dogs (n=117) compared to heavy metal, psychoacoustically designed classical music for dogs and a no music control.
In addition, Bowman et al (2015) recently found that exposure to classical music resulted in physiological (heart rate variability) and behavioural changes suggestive of reduced stress in dogs (n=50), but also raised concerns about habituation to the music, which may suggest that effective utilisation is limited to short-term application, unless habituation effects can be mitigated; for example, through variation in the playlist (Bowman et al, 2017).
Classical music is not the only auditory stimuli found to be beneficial in dogs. Bowman et al (2017) investigated the effects of five distinctive music genres (classical, soft rock, motown, reggae and pop) on kennelled dogs (n=38), and found that under all conditions, the dogs exhibited decreased stress both behaviourally (more time lying and less time standing), and physiologically (via measurements of heart rate variability). The study authors suggest that soft rock and reggae seemed the most beneficial genres of music.
In addition, Brayley and Montrose (2016) investigated the effects of audiobooks, among other music genres (classical music, pop music, psychoacoustically designed dog music and no auditory control) on the behaviour of kennelled dogs (n=31). They found that exposure to audiobooks resulted in increased resting, and reduced sitting and standing in the dogs compared to all other conditions.
In addition, the study suggested audiobooks may be more effective at reducing stress-related behaviour than classical music in kennelled dogs. This may be because audiobooks provide a simulation of human interaction and, therefore, offer the illusion of human company – something dogs value highly.
If using auditory enrichment for dogs, it is important to consider that not all music genres are beneficial for dog welfare; for example, exposure to heavy metal music can increase barking in dogs (Wells et al, 2002; Kogan et al, 2012), reduce sleeping and induce nervous body shaking (Kogan et al, 2012), while psychoacoustically designed classical music for dogs, pop music and radio talk shows do not seem that effective at ameliorating dog stress, at least via the behavioural indicators utilised (Wells et al, 2002; Kogan et al, 2012; Brayley and Montrose, 2016).
The latter is worth considering. When music is played in shelters and practices, it is often radio stations with a mixture of conversation and pop music. The research suggests this may not be that beneficial for dogs, and other genres or use of classical music or audiobooks may be more appropriate.
Surprisingly, considering the highly sensitive olfactory acuity in dogs, relatively few studies have been conducted on olfactory enrichment in this species.
Graham et al (2005a) examined the effects of four diffused essential oils (lavender, chamomile, rosemary, peppermint; and odourless control) on the behaviour of kennelled dogs (n=55).
Dogs were found to vocalise less and rest more frequently when exposed to lavender or chamomile odour, suggestive of relaxation and enhanced welfare. However, exposure to peppermint or rosemary resulted in more barking, standing and activity in the dogs.
Binks et al (2018) investigated the effects of vanilla, coconut, ginger and valerian upon kennelled dogs (n=15). The study authors found the dogs showed reduced levels of vocalisations and activity under all conditions, with coconut and ginger additionally increasing sleeping behaviour.
Both these studies are suggestive that use of olfactory enrichment provides a valuable method to reduce stress in kennelled dogs. It is also worth noting that the two studies applied scents using differing approaches – diffused essential oils and scented cloths – suggesting that both methods of olfactory delivery are effective in ameliorating stress in dogs.
Little study has occurred of visual enrichment in dogs, though Graham et al (2005b) investigated the behavioural effects of five forms of visual stimuli (control, blank television screen, moving television images of dogs, moving television images of animals such as penguins and polar bears, moving television images of people sitting and walking in a house) on kennelled dogs (n=50).
The study authors found that dogs spent significantly more time looking at the moving images than the blank screen, and showed less vocalisation and activity in the television conditions compared to the control condition.
However, in all the experimental conditions, the dogs quickly habituated to the presence of the television monitor, and the dogs also seemed relatively uninterested in the televisions (only 10.8% of their time was spent looking at the screens).
Considering these findings, alongside the cost and issues inherent in utilising this form of enrichment, the research does not support using this approach with kennelled dogs – particularly considering the positive findings found with other forms of sensory enrichment, such as auditory and olfactory stimulation.
In conclusion, sensory enrichment seems to be an effective method for enhancing dog welfare.
Use of auditory enrichment, such as classical music and audiobooks, as well as music genres such as soft rock and reggae, seems to be beneficial in decreasing stress in kennelled dogs. In addition, use of olfactory stimuli, such as coconut, ginger, vanilla, and lavender reduce vocalisations and activity in dogs, again suggestive of reduced stress.
Both these approaches are relatively straightforward to implement in practice, and provide effective and relatively inexpensive methods to enhance dog welfare.