[tareqak]

Oh, I agree with that: most people who have cats have them for companionship, and they don't think about the things that said choice externalizes. However, the same can be said for people who have dogs for companionship. Some dogs routinely lunge at people passing by. In addition, despite the best efforts of those who walk their dogs, there are smears of dog feces on sidewalks. Both situations are examples how keeping a dog has externalities.

[jessaustin]

On a cycle path that was closed by floodwaters earlier this week, already last night there was dog feces. Dog owners DGAF.