MOST SMALL PETS SEEM TO ENJOY RUNNING ON AN EXERCISE WHEEL.
Animals, such as pet hamsters, really do enjoy exercise wheels, suggests a new study that found most small wild creatures voluntarily use the wheels when they encounter them.
The study, published in the latest issue of Proceedings of the Royal Society B, is the first to look at wheel running in the wild.
“Locomotion can be inherently rewarding for animals,” Johanna Meijer, a professor in the Department of Molecular Cell Biology at Leiden University Medical Center, told Discovery News. She co-authored the study with colleague Yuri Robbers.
Like other rodents, hamsters are highly motivated to run in wheels; it is not uncommon to record distances of 9 km (5.6 mi) being run in one night. Other 24-h records include 43 km (27 mi) for rats, 31 km (19 mi) for wild mice, 19 km (12 mi) for lemmings, 16 km (9.9 mi) for laboratory mice, and 8 km (5.0 mi) for gerbils.
Hypotheses to explain such high levels of running in wheels include a need for activity, substitute for exploration, and stereotypic behaviour. Alternatively, various experimental results strongly indicate that wheel-running, like play or the endorphin or endocannibinoid release associated with the ‘runner’s high’, is self-rewarding.
Wheel use is highly valued by several species as shown in consumer demand studies which require an animal to work for a resource, i.e. bar-press or lift weighted doors. This makes running wheels a popular type of enrichment to the captivity conditions of rodents.
Captive animals continue to use wheels even when provided with other types of enrichment. In one experiment, Syrian hamsters that could use tunnels to access five different cages each containing a toy, showed no more than a 25% reduction in running-wheel use compared to hamsters housed in a single cage without toys (except for the running wheel).
In another study, female Syrian hamsters housed with a nest-box, bedding, hay, paper towels, cardboard tubes, and branches used a wheel regularly, and benefited from it as indicated by showing less stereotypical bar-gnawing and producing larger litters of young compared to females kept under the same conditions but without a wheel. Laboratory mice were prepared to perform more switch presses to enter a cage containing a running wheel compared to several meters of Habitrail tubing or a torus of Habitrail tubing.
Running in wheels can be so intense in hamsters that it may result in foot lesions, which appear as small cuts on the paw pads or toes.Such paw wounds rapidly scab over and do not prevent hamsters from continuing to run in their wheel.
The reliability which hamsters and other rodents such as mice, rats, flying squirrels, and degus use running wheels has made voluntary wheel running one of the most widely used indicators of activity and wake-time in research on circadian rhythms and other aspects of microbiology.
Miniature running wheels have even been used to measure the circadian loco-motor activity of cockroaches. For rodents, running wheels are easier to set up and automate than other techniques of activity recording such as bar-gnawing and spring-suspended or knife-edge balanced cages.
In rodents, voluntary exercise is almost always measured by use of wheels. This makes running wheels the tool of choice in research on the effects of exercise on metabolism and obesity.
The neurotransmitter systems involved in wheel-running behavior have received considerable study.
Recent evidence suggests that changes in both dopaminergic and serotonergic tone alter running-wheel activity.
For example, one study in mice has shown that several antidepressant medications (all of which directly or indirectly enhance serotonergic tone) suppress running-wheel activity without suppressing general locomotion.
The endocannibinoid system also contributes to wheel running in a sex-specific manner in rodents.
Mice from lines that have been selectively bred for high levels of voluntary wheel running have altered responsiveness to drugs that alter dopamine and endocannibinoid signalling, and enlarged mid brains.
When Wild Animals And Pets Use An Exercise Wheel.