Over the years, it has always been something of a surprise that so little attention has been given to a better understanding of dog (and cat) demographics in human society. There is a large variation in the results from different surveys with the reported percentage of US households with pets ranging from 49% to 68%.
Rowan, Andrew N.
"How Many Dogs Are in a Particular Place or Region?,"
WellBeing News: Vol. 1:
6, Article 4.
Available at: https://www.wellbeingintlstudiesrepository.org/wbn/vol1/iss6/4