Cage size affects comfort, safety and the experienced security of working dogs in cars

Working dogs often spend a large amount of their time in cars. It has been hypothesized that a larger compartment in the car would be more comfortable for the dog, but that a smaller space could be safer, especially while driving. This presents a potential conflict. In this study, working dogs of the breeds German Shepherd (N = 8) and Springer Spaniel (N = 8) from the Swedish Police and Customs respectively, were each tested in four different car cage sizes; two cages were the minimum size allowed according to Swedish regulations (one of fixed size and one adapted to the size of the dog) and for comparison we tested one larger (fixed sized) and one smaller (adapted sized) cage. These were tested under two different driving phases; normal driving (including turns and changes in speed) and slow cruising (without turning forces and of an even speed). The study was conducted at a test track using an estate car, typical of that used by these organizations. Testing of each cage size involved 30 min in the car, excluding the habituation period. The dogs’ behaviour and heart rate activity was recorded. Statistical analyses used a mixed model and pairwise comparisons. We found a large effect of our two driving phases, for example heart rate was higher and behavioural stress indicators more frequent during normal driving, implying that this was a more demanding situation for dogs compared to the slow cruising. Regarding cage size effects, there were fewer overall movements and body position changes by dogs in the three smaller cages compared to the largest cage size. That this could be a sign of decreased comfort is supported by the finding that dogs could not turn around in these cages without curving their back upwards or lowering their rump in these cages. This could have negative physical effects, especially in German Shepherds which are predisposed to musculoskeletal disease. Furthermore, German Shepherd dogs showed more bracing postures, i.e. more attempts to maintain their balance, in the small fixed cage size. For these dogs this cage size was shorter than their own body length. However, this bracing did not result in them losing their balance any less often, illustrating the importance of space allowance for maintaining balance during transportation and implying that a smaller cage is not necessarily safer.