Why was a legendary French greyhound venerated for centuries by a religious cult?

Would you believe that Guinefort the 13th century greyhound was venerated as a saint? The legend goes that a knight left his infant son in the protection of the dog Guinefort. When the knight returned there was blood and the nursery was in disarray. The knight killed the dog before discovering the child was fine and the dog had killed a snake. When the town found out about the dog deed they venerated him as a saint.

https://en.wikipedia.org/wiki/Saint_Guinefort

The story goes that Saint Guinefort, a greyhound that supposedly belonged to a French knight in the city of Lyon, was killed by its owner by accident. The knight believed that the dog had killed his child, but instead, Guinefort had protected the child from a viper. When the knight understood his mistake, he and his family buried the dog in a well and the site turned into a shrine where locals would go in their time of need. Saint Guinefort was since venerated for centuries by a cult, in defiance of the Catholic Church.

Sources: https://en.wikipedia.org/wiki/Saint_Guinefort
https://www.redlandsdailyfacts.com/2016/05/18/professing-faith-role-of-dogs-in-the-history-of-religion/