Magic or spells. In many fictional worlds, magic is a powerful force that can cause all kinds of transformations. If a magician casts the wrong spell or if there's some sort of magical accident, a man could turn into a dog.
Some sort of scientific experiment gone wrong. In science - fiction - like stories, a scientist might be working on a genetic - altering experiment. If something goes haywire, it could lead to a man transforming into a dog - like creature. This often explores the idea of the dangers of playing with nature without fully understanding the consequences.
A curse. This is a very common reason. Maybe the man has angered a witch or some other supernatural being. As a form of revenge, he is cursed to live as a dog. It's a way to teach him a lesson or just to make him suffer for his actions.
Another possibility is a curse from the supernatural world. Maybe he entered a haunted place or broke an ancient taboo, and as a result, a curse was placed on him to transform into a dog as a form of penance or to teach him a lesson about respecting the unknown.
It might be that the man made a deal with a witch and broke the terms, causing the transformation. Or it could be a symbol of his inner transformation and represented metaphorically as a physical change into a dog. There could also be a virus or a strange potion involved.
It could also be due to a curse. For example, he might have offended a powerful witch or wizard who put a spell on him, causing him to transform into a monster. Another reason might be his own inner demons. If he had been suppressing a lot of anger, hatred or negative emotions for a long time, it could have manifested physically and turned him into a monster.
One reason could be that the dog is feeling threatened. For example, if the man accidentally steps into the dog's territory, like its yard, the dog may bite to protect its space.
One common reason is for performance. As in theater or film, a male actor might transform into a woman to play a female role. Another reason could be for self - discovery. A man might want to understand what it's like to be a woman, so he undergoes a transformation. Sometimes it's for a bet or a challenge too.
One possible reason could be self - defense. If the dog was attacking him and he had no other means to fight it off, he might have bitten the dog.
One possible reason could be psychological. As she grows up, she might start to imitate her mother unconsciously. For example, she may adopt her mother's mannerisms, like the way her mother talks or gestures. Another reason could be environmental. If she is constantly surrounded by her mother's influence, such as living in the same house with all her mother's things around, she may gradually transform in some ways. Maybe she starts to take on her mother's role in the family, like taking care of younger siblings just as her mother did.
One possible reason could be mental distress. He might be suffering from depression or some other psychological disorder that made him feel hopeless. Maybe he had financial problems, lost his job, or had relationship issues.
Betrayal could also be a cause. In some fictional tales, if a man betrayed his comrades or a powerful entity, that entity might use magic to turn him into a statue. It's a way of imprisoning him in a form that can't interact with the world anymore. For example, if a knight betrayed his king and made a pact with the enemy, the king's wizard could turn him into a statue.
It could be that he had a past experience related to a dog. For example, he might have been saved by a dog when he was a child or had a special encounter with a dog that made him feel a connection. This connection then drove him to save the stray dog from drowning.