Electronic fences and their partners collars that deliver an aversive agent have been around for more than 20 years. They seem like the perfect canine confinement alternative to a solid physical fence. They are often marketed as the ideal fencing solution to homeowner association fence prohibitions and for problematic, difficult-to-fence, steep, rocky and rugged living spaces. But while occurrences of a collar shorting out and administering repeated shocks to a hapless, helpless dog are relatively rare, there are other drawbacks to using electronic fencing systems. A conscientious owner will weigh all the pros and cons before deciding whether or not to invest in this sort of fencing" system. "