Hate to say it, but your friend might be a sexist.
I'm a dog owner and work in the pet industry, I have yet to come across any breed (and there are hundreds) that is born with a prejudice against certain humans. There are definitely dogs who shy away from certain people (like men, people wearing hats, people with different skin color, etc) but this is usually because of some sort of trauma in their past. Dogs are not born to hate anything just like humans are not. It sounds more like your friend is making an excuse for the dogs behavior instead of taking responsibility. More often than not dogs pick up on your energy so when you're anxious they become edgey, and naturally when you act threatened or stand-offish, they feel the need to protect (or flee!). Therefore, if you're friend has a problem with men, her dog might be naturally picking up on those vibes. Confront your friend if you feel like it, or don't, but she definitely doesn't know what she's talking about when it comes to certain breeds hating certain people :p

No idea, but the dog I had growing up hated men with beards. I figured since my parents had no bearded friends, he wasn't used to seeing that much hair on humans and thus was mistrusting. It might be the case with your friend's dog. Never exposed to men, therefore doesn't like them.

it might not be sexism, but hyper-vigilance that your friend is experience

My dog was racist, which was weird because our house was always full with a diverse social group. We figured he was just born that way.

My female dog didn't like my male friends (I'm male) - she kept a very close watch on them at all times when they visited.

However, she was quite a bit more relaxed when GF's female friends came by.

Dogs can like or dislike things about groups of people, just like people can (and do).

People are supposed to treat all other people equally though, at least until the other party has done something to deserve less respect.

It's hard to teach dogs about equality though.

But your friend could well be putting her prejudices into her dog's "mouth" (so to speak).

Her saying that an entire breed doesn't like men is certainly untrue and almost certainly projection on her part.

I am a crazy cat man.

Had a male friend with a cat, he lived alone with the cat. The cat liked me as I'd go over for tea now & again. Adopted the cat when my friend moved away. Discovered the cat hated women except for me. Would slash at female visitor's ankles from under my couch (attack cat!). Found out at this time my friend was gay. He never had other women other than myself come visit so I would assume it was a familiarization thing on the part of the cat.

because they are just animals, fer fucksakes. I grew up with two dogs and two cats. I'm not afraid of, nor do I dislike them. It doesn't appear to matter how I feel about animals, some of them are friendly with me and others, like my neighbour's yappy mutt, growl and bark at me every single day. I've never done anything to make the dog dislike or mistrust me, some dogs are just stupid. I've love to give that damned thing a drop kick to the gonads next time it terrorizes me while I'm just trying to get into my home.

Sexist!? Oh good lord.

We had a dog that hated men standing near street corners at night talking on cell phones. Growled, acted paranoid and freaked out. He was second hand, so maybe there's some story we never heard.

Most small dogs fear small children (dangerously so) , probably likewise from some bad experience. Or just because most small dogs are spoiled, violent little shits with a napoleon complex.

Animals over-generalize from their experiences, especially early ones, just like people do.