Why does toto distrust the scarecrow at first?

Toto initially distrusts the Scarecrow because he perceives him as an unfamiliar figure and a potential threat. As a dog, Toto is instinctively cautious around beings that look strange or unusual. The Scarecrow, lacking a human-like appearance and being made of inanimate materials, raises Toto’s suspicion until he gets to know him better. Ultimately, Toto's wariness fades as he realizes the Scarecrow means no harm.