I based it off facts... "According to the American Community Survey, in 2016 there were about 115,000 children under 18 living in the city. At the same time, San Francisco Animal Care and Control estimated there were about 120,000 to 150,000 dogs in the city." Source: Are There Really More Dogs Than Children in S.F.?
It's really common in SF, actually, that saying... You'll hear it constantly in San Francisco, "This city has more dogs than kids." I was there for only a week last trip, heard it 5 times))