With the exception of rabies, most of the diseases transmitted from dogs to humans do not attract much public attention. However dog waste, a perennial nuisance in cities, is more than just an aesthetic problem. Dog faeces in public areas allow parasite transmission from dog to dog, and are also a human public health issue. There are numerous studies establishing that dogs are frequently parasitized by Toxocara canis, and failure to clean up after dogs seeds the environment with Toxocara eggs. It is now widely recognized that the ingestion of embryonated Toxocara eggs can cause human illness such as toxocariasis or visceral larva migrans. The disease appears to have two forms, one involving an intestinal migration and the other having ocular involvement (Glickman and Shofer, 1987).
The best way to lessen the occurrence of parasite contamination is routine veterinary care. Animals that are routinely ‘de-wormed’ do not pass contaminated faeces, which is particularly important for those dog owners with young children. Dog waste, apart from being a source of parasites, is viewed as a kind of environmental pollution. To address this problem, most large metropolitan areas in North America and Europe have laws that restrict the activity of animals, especially dogs, in public areas. Most cities in the United States prohibit pets from entering restaurants or food stores, or going on public transportation, except for animals in enclosed carriers or service dogs assisting people with special needs.
One of the most common regulations to reduce dog waste in public areas is to encourage or require dog owners to have their dogs use the street, rather than sidewalk, for defecation, the so-called ‘curb your dog’ laws. In this way people do not step into waste, which is carried to storm drains during street washing or rain. In addition, most cosmopolitan centres encourage or enforce ‘scoop laws’ so owners clean up after their dogs in public (Beck, 1979; Brandow, 2008). Basic courtesy permits dogs and people to share the cities in ways that benefit both.