Since a lot of trash is thrown outside, dogs will look through the trash and find scraps of food to eat. In other countries I've visited, the stray dogs are very skinny because they have a hard time finding food. Here, all the dogs actually look very healthy!
Besides dogs fighting and harming each other, the biggest threat to dogs is not having caregivers. When they get old or sick, no one is there to take care of them. I am worried for the dogs of Kathmandu, but thankfully, there a lot of shelters here that pick up dogs and provide a home and food for them.
