Some SHUNGA are parodies of masterpieces such as The Tale of Genji Edo perid.
This SHUNGA is also parody.
The base story is “南総里見八犬伝(Nanso satomi hakkenden)” which is very popular novel released on the same age.
The dogs appear in “南総里見八犬伝(Nanso satomi hakkenden)”.
But there are not the situation of animal sex in that novel..
Koi no yatsufuji