Here's why:
* Grammar: We use "he" as the pronoun for a dog of unknown sex.
* History: Historically, dogs were primarily used for hunting and other "masculine" tasks.
* Cultural Usage: The term "dog" often carries connotations of strength, loyalty, and protectiveness, which are traditionally seen as masculine traits.
However, it's important to note that:
* "Dog" can refer to both males and females. It's only considered masculine in the generic sense.
* We use "she" for female dogs when we know their sex.
* "Bitch" is a term for a female dog, but it's considered offensive in many contexts.
So, while "dog" is considered masculine grammatically, it's not inherently so. The use of "he" as the pronoun for a dog of unknown sex is simply a grammatical convention.