There are hundreds of animals in the forest, and nobody seems worried how their waste products affect the environment, so why should you worry about pet waste?
According to the U.S. Humane Society, 40% of United States households have at least 1 dog. Assuming Duluth is average, there are at least 125 dogs per square mile in the city (based on 21,000 households). This is a much higher population density of large mammals than you would find in a natural forest. You would expect to find an average of 4 fox, 0.8 coyotes, 0.1 wolves, 2.6 raccoons, 0.1 lynx, 0.6 bobcats, 8.5 skunks and 0.2 bear per square mile in undisturbed areas.
High animal populations yield lots of waste for the ecosystem to decompose. In a natural forest, this waste would slowly be broken down by microorganisms and would then be filtered through the soil by rain and snowmelt.
In an urban setting, the natural system has been altered by increased runoff due to impervious surfaces (surfaces that do not allow water to infiltrate the soil including rooftops and asphalt or concrete roads, parking lots and sidewalks). Pet waste that isn’t properly disposed of will often be flushed into streams and lakes before being completely broken down.
Contaminants in Pet Waste
Pet waste may contain pathogens such as bacteria, viruses and parasitic worms that can be transmitted to humans who are gardening in contaminated soils or who are recreating in infected waters.
Some specific diseases and parasites carried in pet waste are:
Campylobacteriosis – a bacteria carried by some cats and dogs causing gastrointestinal illness (diarrhea) in humans
Cryptosporidium – a protozoan parasite that can be carried by dogs, cats, mice, some farm animals, and many other mammals causing gastrointestinal illness in humans. Common symptoms include diarrhea, stomach cramps, nausea and dehydration.
Toxocariasis – roundworms that may be transmitted from dogs to humans often without obvious symptoms; may cause vision loss, a rash, fever, or cough.
Toxoplasmosis – protozoan parasite that may be transmitted from cats to humans that can cause birth defects such as mental retardation and blindness if a woman becomes infected during pregnancy; symptoms include headache, muscle aches, lymph node enlargement.
All of these diseases are of particular concern if contracted by people with with depressed immune systems.