A strangled dog and a hat box? Some implausible plot devices

good points.

I hated Jaws, it had too much shark, and dont get me started about King Kong, waaay too much gorilla

I think you missed the point. The dog was never buried in the garden! Or placed in the hatbox. And strangling does cause eyeballs to bulge and tongues to swell with blood and protrude. If I remember Silent Witness and Patricia Cornwell's novels correctly...

The murdered wife's head would not fit in the suitcase that Thorwald put the other body parts in (the only reason I see for it not being removed with them), so he buried it in the garden under the zinnias (in a cute very British idea). And the dog refused to leave it alone. So he killed the dog. And the huge scene the owner made necessitated Thorwald getting the head out of there--in the hatbox? Or maybe it was buried in the hatbox--the head, not the dog. ;)

That is how I understood that part of the mystery. I could be wrong, but I just figured the censors would not let them openly discuss a severed head buried in the garden and unearthed by a dog, and placed in a hatbox--before or after burying, I don't know. If you are a fan of British mysteries, it all seems pretty obvious. Being Hitchcock was from Britain, it all made sense of sorts...

I'm glad you have given a reason against the justification of the dog's death. I just don't like this part of the movie. So much so that it spoils my enjoyment of the film now. I do have a particular aversion to pet deaths in films anyway. But Hitchcock seemed to introduce these in a few of his films.

Neighbour: "It's dead! It's been strangled and its neck is broken!" I do appreciate that this keeps the plot moving but that woman's diagnosis is pretty rapid.

For me, the worst plot device is the f-cking ring!
She didn't take it with her, therefore she is dead. WTF?
And then Grace Kelly stole it and that would prove it all. How? That would only make her look like a burglar.

It isn't Miss Lonelyhearts that declares the dog has been strangled. She is the neighbor of the female dog owner.
It isn't even the female dog owner who declares that the dog has been strangled. It's her husband.

Also, Thorwald never put the dead dog in a hat box in his apartment. Watch the movie again.

"So Miss Lonelyhearts declares that the dog has been strangled. How does she know? It's very hard to detect strangle marks on a dog with all that fur. Is she a vet? I hardly think so. This observation is necessary in order to suspect Thorwald of this murder and to set of the digging and breaking in in his apartment. The dog could have fallen off the balcony and broken his neck. So this "he's been strangled" is of vital importance for the furthering of the plot."

But this is nitpicking, nothing more. The suspension of disbelief does not fail at this point.

"Why did Thorwald kill that dog? Yes, he's been snooping around in his garden. But it gets weirder: after he had killed the dog apparently he dug it up and put it in a hat box in his apartment. So...why not do that in the first place without arousing suspicion with the dead dog? And after he had killed the dog why would he worry about it? There aren't any other dogs in the neighborhood."

Thorwald didn't put the dog in the hatbox. The dog was hauled up by the owners of the pully system installed by its owners. Thorwald left the hatbox under the zinnia.

I apologize, I was mistaken about the hatbox. You were correct, it ended up in Thorwald's apartment. 😱