Number of dogs was not as high as today.We forget.......dog food...until probably the 1930s dogs DID survive on table scraps and foraged.
There was no" dog food"
My grandmother even in 1950 gave her dog bought food... . raw .horse meat! and was some by then canned K-L Ration
Over 3/4 of all the ppl were farmers before the Great Depression and so in the country they were other things dogs caught themselves rabbit possum and such and plus inners fro m chicken cows and whatever else the farmers gutted. Im sure few were really heavy like today more thin or skinny dogs.