According to the American Veterinary Medical Association (AVMA), most communities do not have data on the number of households that own dogs, nor do they have data on the numbers of these pets in their communities. However, the number can be estimated, even if many pet-owners fail to register their pets.

Why? It's interesting to know how well your community is considering life for its non-taxpaying four-legged citizens, particularly in urban areas that are gentrifying, but may not be quite set up for an explosion in the dog population . As warehouses and old courthouses are turned into residential housing, where are the parks for people and their dogs?

Advises the AVMA, "To use the formulas on these pages you need to know the total number of households in the community in which you are estimating. If you only know the population of the community, you can estimate the number of households by dividing the population of the community by the average number of members per household. In 2000, the U.S. Census Bureau estimated that there were 2.67 members per household.

The formula recommended by the AVMA to figure the number of dog-owning households in your area is: number of dog-owning households = 0.361 x total number of households.

To find out the number of dogs, try these formulas: number of dogs = 0.58 multiplied by the total number of households or number of dogs = 1.6 multiplied by the number of dog-owning households.

Using it's own formula, the AVMA estimates that approximately 31.6 percent of American households include a dog, and as many as 21 percent include more than one dog. (The American Medical Association says there are about 65 million dogs in U.S. households.)

This information can be useful in determining a community's needs for such necessities as dog parks, doggie day care facilities, pet-sitter/groomers, rescue centers and pet stores, among others.

It can also be used by communities to cope with one of the downsides, pardon the pun, of dog ownership. Over a 10-year lifetime, according to research performed by the BBC in London, a dog can produce as much as a half-ton of feces.

A Cambridge, Massachusetts dog-owning group makes several points in its petition to the city to designate more "off-leash" space.

Among the petition's points:

• Sanctioned off-leash areas (also known as dog parks or dog runs) are not a new concept, with the first ones introduced more than 20 years ago. There are currently over 700 off-leash areas in the United States, with new spaces added frequently. Their benefits are numerous, affecting both dog owners and non-dog owners alike:

• Relieved usage of other public recreation areas (especially children's playgrounds and other areas where interactions with dogs may be unwelcome.)

• The presence of dogs and their owners can revitalize little-used areas and may deter crime.

• Many studies show the benefits of animal companionship to the elderly and people with disabilities. Off-leash areas are often the only place where they can exercise their pets.

• In a city, people can be reluctant to approach their neighbors. Off-leash spaces engender community by bringing people together.

• Reduced demand on animal control officials to enforce leash laws, allowing them to focus on other issues

• Increased responsible dog ownership (including cleaning up after one's dog and controlling his/her behavior). Peer influence has been demonstrated to be more effective than other types of enforcement in such situations.

• Socialized, well-exercised dogs are calmer, more well behaved, and less likely to develop aggressive tendencies than dogs that are under-socialized and under-exercised.

• Separate areas for off-leash recreation allow dog-owning park users a space to gather without infringing on the rights of others, who may choose not to interact with dogs.

• Off-leash areas provide a place where people can exercise with their dogs, contributing to improved health and physical fitness.

Dogs can be the harbinger of urbanization and things to come. In this recent LA Times story , a man found downtown lofts allowed pets while other landlords in the city didn't want them. Something to be said for indestructible concrete floors.

Dogowners have responsibilities, too, namely to pick up after their dogs and train them so that others are safe from disease and from being pawed, or worse, bitten. Should the worst happen, dog bites are generally covered under homeowner's or renter's insurance. Some guarding and large-size dogs may be exempt from coverage so it's up to the dog-owner to make sure they're covered.