Is it really a widely held belief that those who dislike animals are dangerous?

This.
My Lab loved everyone though, apart from one woman I worked with who he just stared at. She was a wrong un, so he was right lol
Not liking them is fine as long as you aren’t cruel to them. Just leave them alone.

Your DH family are bonkers.

I was going to mention Hitler - famously loved animals and became a vegetarian and third reich was apparently good on animal rights and even environmntal laws - famously much less good on human rights.

I'd try pointing that out to her - or just tell her outright she being very rude and ignorant - maybe with a breezy tone and smile.

I’m suspicious of anyone who doesn’t like dogs.

Perhaps point out to your MIL that Hitler adored dogs, especially German Shepherds. He kept one of his pets, Blondi, with him to the last in the bunker under Berlin (though he did test the cyanide capsules he used to commit suicide on the dog first)...

Hating animals would be concerning.

Disliking them, especially if for a good reason, isn’t.

Your MIL is projecting HER failure with HER dogs onto you. A lot easier than actually looking after them properly, training them etc.

I love animals and I do sometimes struggle to understand people who don't like them. I probably couldn't have a successful relationship with someone who didn't, for example; we'd just be too different. But I certainly don't think it means someone's dangerous or unpleasant!

If someone is cruel to animals (or just really cold and callous about them) that's a red flag for me. But I wouldn't think badly of someone who just wasn't really interested in animals or had a phobia of them or whatever. Most people I've met who aren't keen on animals would never be cruel to an animal, would never wish harm on one, and would also feel sorry for an animal that was suffering.

Your MIL sounds a bit mad to be honest.

Your MIL is BU. I'm a vegetarian and care a lot about animal welfare, but I've never wanted pets and avoid other people's, with the exception of some very calm and elderly dogs. I'm averse to pet smells and being jumped on or scratched/bitten.

I don't think it's a sign of anything in particular.

I’ve seen the view fairly regularly expressed on MN that people who don’t like animals are cold and dead inside 😆. It’s nonsense of course but some people do like to say it.

A member of my DH’s family once told me that refusing to have a dog made me a bad mother.

Putting my parenting side by side with her’s I’m pretty comfortable that I’m still ahead despite our lack of canine companionship.

How do you manage not to say "Oh, I don't mind trained dogs, they're much nicer easier!"

Hitler really liked dogs, not so much a people person though. People who want to hurt others or animals are disturbing, people who aren't interested in animals just aren't an issue (and less exhausting to deal with than the obsessed/worshipping people, frankly).

I'm guessing you're right and she's just not keen on you. Not very nice of her to let it show though.

No.

They will have met people who don't like the dogs, they will just have been able to hide it for the duration.

Not being interested in animals is not the same thing as actively disliking them and wishing them harm. Your MIL is wrong and being unpleasant to say to you that it's some kind of red flag and that you have a personality disorder! What does your DH say when she says things like this? I hope he challenges her!

I wasn’t an animal person then we got a pet dog that I absolutely love but I don’t think it made me a better person. YANBU.

Yep, I've found that too.

Slightly off topic, but in the past men my pets didn’t like turned out to be dickheads 🤣

I've seen this sentiment before, usually in the sort of people that treat dogs as human substitutes that have to go everywhere with them. Obviously it's bollocks, some people are more into animals than others and as long as you aren't mistreating them it's no ones business.

If you eat animals, you condemn them to barns and cages until someone is paid to slit their throat, gas them or put a bolt through their head. That's incomparable cruelty to me.

I always seem to gravitate more towards people who actively like animals and are comfortable around them. I usually find them warmer and less up tight but I'm sure there are some absolute bastards out there who happen to love animals too. Anyone who finds pleasure in hurting animals (obviously not you OP) is almost invariably honing their perverted skills before they turn to humans. That is a fact.

It's widely held by animal people, or I would say mainly dog people. Personally I find an OTT love of dogs far more alarming than a dislike of them. Most dog forums or dog lover communities, even the doghouse on mumsnet of all places are toxic places when there is a disagreement where people use their love of dogs to bully others and cause a pile on. You can see it on threads where people say they are scared of dogs too. They're told to get over it and sometimes even flooded with dog photos which I find to be disturbing. No other phobias are treated with so much disdain or mockery.

I think dog owners when they tip over a point are socially maladjusted and even narcissistic at points. At points even other dog owners rush to preemptively defend themselves against other dog owners by prefacing their posts they don't walk Fido over a certain temperature when nobody asked.

Other animal keeping hobbies don't seem to be the same. The cat/fish/reptile/rodent community doesn't seem to care as much if you don't like their pet of choice. I keep a range of pets and if you don't like them I can see why - they're stinky and don't know how to use a toilet and make alot of mess.

i can understand indifference, but I’d be a bit wary of someone who isn’t moved by nature documentaries where animals die a horrible death.

Your MIL sounds like one of those people whose life revolves around her dogs. Urgh. Just ignore her, she clearly can’t accept the concept that someone doesn’t love the same things she does.

No, she is getting confused, people who hurt animals are danderous. I actually suspect that people who prefer to leave animals alone are less dangerous than 'animal lovers'.

I think your MIL doesn't like you and is not a particularly nice person.

Well who knew. I'm dangerous am I? 😂 I'm the same as you and don't like dogs and cats. Is your mil on MN because I got called a psychopath for hoovering up spiders🤣 does your DH have the same view as his mom?