The effects of kennel size and exercise on the behaviour and stress physiology of individually-housed greyhounds

Highlights

• There was no evidence that smaller kennels disrupt biological function.

• Implications of floor space for younger dogs is less clear.

• There was no effect of exercise on the measurements regardless of kennel size.

• The larger kennels may provide better opportunities for social contact.

Abstract

Greyhounds are routinely bred and managed for racing and are usually housed in individual kennels. To address the question of whether greyhounds would benefit from an increase in the minimum kennel size specified in the Victorian Code of Practice, the effects of kennel size and routine exercise on dog behaviour, stress physiology and injuries were examined. A total of 36 healthy greyhounds (aged 17 months (replicate 1 and 2) and 12 months (replicate 3)) were studied in three time replicates in a 2 × 2factorial experiment (kennel size of 3 m² and 10 m² of floor space, and two levels of exercise (‘no exercise’ and ‘exercise’(consisting of 2 × 10 min per day and 3 times per week chasing a lure)) over 6 weeks. During the 1st and 5th week of treatment, dog behaviours were recorded for 2 days in their kennels using time-lapse video. During the 6th week, six saliva samples were collected to measure basal cortisol concentrations, an ACTH challenge test was performed and injuries were assessed. Intensity of exercise had no significant (p ≫> 0.05) effect on behaviour, stress physiology and injuries. In the 1st week the adult dogs in large kennels spent more time in the front of the kennels (p ≪ 0.05), less time in the back of the kennels (p ≪ 0.01), less time lying (p ≪ 0.05) and more time standing (p ≪ 0.01) than those adult dogs in the small kennels. In week 5, the younger dogs in the large kennels spent more time at the front of the kennel (p ≪ 0.05), less time in the back (p ≪ 0.01) and spent more of their lying down time at the front and middle of the kennel (p ≪ 0.001) than dogs in the small kennels. No significant differences in any of the measurements were found in the adult dogs in week 5. No abnormal or stereotypic behaviour was observed in Week 1 or 5. No significant differences in injuries, saliva cortisol concentrations and maximum cortisol concentrations in response to ACTH were found. The results of this study do not provide evidence that the smaller kennels and limited exercise increase the risks to dog welfare based on behaviour, stress physiology and injuries. Nevertheless, the observation that dogs tended to spend more time in the front of the large kennels where they were in view of other dogs could indicate that larger kennels may enable better welfare by providing additional social contact.

Introduction

Spatial requirements for individual animals kept in confinement involve space for their physical size and basic movement as well as space to perform a range of behaviours that are likely to affect their welfare (Petherick, 1983). Furthermore, many species (e.g., dog, pig, rat, mouse) are motivated to separate several important functions, for example elimination and lying (resting/sleep).

Limited studies have examined the effect of floor space on dog welfare. Indeed, in a review of the literature on the effect of the kennel environment on the welfare of dogs Taylor and Mills (2007) concluded that due to the lack of single variable studies the relative effects of factors within the environment are not known. Two studies (Campbell et al., 1988, Hite et al., 1977) indicate that for purpose-bred beagles, changes in floor space in the range of 0.58 m² to 2 m² per dog did not adversely affect stress physiology or immune measures indicative of stress. However, one could argue that this range in floor space may be sub-optimal. Most studies found little to no effect of space on gross behaviour such as locomotion or activity (Hite et al., 1977, Hubrecht et al., 1992, Hughes et al., 1989, Bebak and Beck, 1993). When dogs housed in indoor pens of 11 m² were given additional access to outdoor kennels of the same size however, they showed a significant increase in activity and more than doubled the number of steps as measured by a pedometer (Spangenberg et al., 2006). This effect may be due to the more complex nature of the outdoor environment, rather than space per se.

Most studies that investigate the effect of floor space are confounded with social contact. For example, Beerda et al. (1999) found that visual and tactile isolation from dogs, together with spatial restriction from 12 to 1.7 m² floor space per animal, resulted in increased circling, eating of faeces, paw lifting, vocalisation and sitting, reduced walking and lower postures. However, within the constraints of the very limited literature, it appears that space may be less important to the dog than social contact (Hetts et al., 1992, Hubrecht et al., 1992, Hughes et al., 1989), especially in the long term. Furthermore, the amount and type of social contact available may be an important determinant of the welfare of dogs that are individually housed.

Little is known about the interaction of exercise with housing condition of dogs. While it is thought that exercise may alleviate boredom and may provide activity for dogs in confinement, there is little evidence that this is indeed the case. No differences were found in behaviour, immunology and physiological measurements between dogs exercising in indoor rooms compared to dogs provided with no exercise (Campbell et al., 1988, Clark et al., 1997). It is possible that the amount of exercise provided (20 min per day, 3 days per week; Clark et al., 1997) or the difference in cage size used (0.58 m² vs 2 m²; Campbell et al., 1988) was not sufficient to allow the detection of any differences.

Carefully controlled studies are clearly required to study the relationship between space and the behaviour and stress physiology of dogs. Greyhounds are routinely bred and managed for racing and are usually housed in individual kennels. According to the Victorian Code of Practice for the Operation of Greyhound Establishments (Victoria Department of Primary Industries, Biosecurity Victoria, Australia, 2012) the minimum floor space allowance for greyhounds in training, or receiving a minimum of 10 min of exercise twice daily, is 3 m², while those not in training should be provided with a floor space of at least 10 m². However, these recommendations are not based on scientific data. To address the research question of whether greyhounds housed in individual kennels would benefit from a larger kennel size, a controlled study was conducted to examine the effects of kennel size on dog welfare. Since greyhounds are generally housed individually when in training for racing, the effects of kennel size with and without routine exercise was evaluated since both factors may influence the dog’s welfare. The normality of biological functioning (Hemsworth et al., 2015), using measurements of behaviour and stress physiology, as well as common fitness variables such as body weight and injuries, were used in this experiment to assess risks to dog welfare.