Dog Owners Explore Possible Reasons When One's Dog Seems Upset For No Apparent Reason
You open the door expecting to be greeted by your beloved pet. After a hard day at work, your dog's greeting is a signal that it's finally time to rest at home.
But your dog doesn't greet you. He just stares at you as if you did something wrong, and then you wonder, "Is my dog mad at me?"
Although experts acknowledge that dogs are capable of experiencing a spectrum of primary mammalian emotions, such as anger, the exploration of secondary emotions in dogs is still in its early stages, according to bioethicist Jessica Pierce, PhD. There is still a lack of comprehensive understanding among experts regarding how dogs perceive and exhibit nuanced emotions such as resentment.
While dogs are capable of expressing anger, behaviors that may appear as signs of them being upset with you—such as growling, ignoring you, or avoiding petting—could actually be responses to changes in their environment.
Other dog owners have also experienced the same thing. We can easily assume that one Quora user recently observed an angry-like behavior in their dog as they asked this question:
What is it like to be a dog owner when your dog gets mad at you for no reason?
Let's take a look at some of the input from other dog owners.
Even dogs get bad days, just like us, humans.
Dogs, like humans, are entitled to having a bad day. I respect my dog's boundaries and give her the space she needs to get through the tough day she's having.
She knows that at any point during that time, if she needs me, I'm not far away. Often, she wants me close by but is grumpy and doesn't want to interact.
She's 10 1/2 years old, so I would classify it not as being 'mad' at me but rather as having a grumpy day. She's old; she's earned it, lol.

It's up to the owner to figure out what's up.
My dog sometimes sits and looks at me. She doesn't tell me what's wrong; she just looks.
I have to figure out what's on her mind.

This owner advises the original poster (OP) that they will eventually figure out why their dog is angry.
First, there has to be a reason; you just haven't figured it out yet. My Pit is always getting mad at me.
She'll turn her back toward me. I laugh at her.
Then I ignore her.
It's usually because I'm moving her stuff. I live in a loft.
She also gets worried if I close the bathroom door. I'm her fourth owner.
I remind her this is her forever home and cuddle her.
Just pay attention, and you'll probably figure it out.

According to this user, jealousy could be the reason why their dog is angry.
There's a reason; you need to figure it out. My boy is currently mad that he's an uncle to my daughter's new pug puppy, and he doesn't want to share me.
While we're working on socializing them, my big boy is getting lots of extras from me, so he's reassured that he's my only boy.

A broken routine could sour a dog's mood.
In the dog's mind, they always have a reason for getting mad at you. They wanted to go when you left, for instance.
Or, with mine, I broke our routine this morning. Or any other thing that you do that upsets him or her.
As an owner, you just ride it out; they get over it.

Sometimes, it takes reflection to determine what makes the dog angry.
Dogs don’t get mad at their owners for no reason. Check yourself.
What are you doing wrong? Are you being insensitive to the dog’s needs?
Dogs have a limited capacity for communicating with humans. They can’t talk, and most humans don’t understand a dog’s non-verbal cues, but they definitely communicate in the only ways they know.
They bark, growl, some smile, some tear things up, they nudge, stare at you, run to an object, etc. It sounds like your dog needs a new home with someone who can appreciate it and will take the time to care for it and learn how to communicate.

Depending on the dog's behavior, the OP might need to take their dog to the vet.
I would be worried. If there really is no reason, you need a trip to the vet.
Chances are there is a dog reason. Have you done something that would make your dog jealous?
For some, even petting another dog will upset them. I’m lucky that my girl gets mad at the dog I’m petting.
Growling ensues. Snapping is possible but has never occurred yet.

Dogs never get angry without a reason. Ultimately, it's the owner's responsibility to determine what's triggering this behavior in their pet.
Changes in their environment, routine, and their owner's treatment could be the reasons behind the dog's seemingly angry behavior. A sudden personality change in dogs should always be a cause for concern.
When things escalate, the owner should take their dog to the vet.