Is there an English metaphor/saying for this expression?

Question

I'm translating a book and the author has written down a saying that can be translated literally as "If you want to hit a dog you can easily/quickly find a stick" Like, if I wanted to hit a dog, finding something with which to hit it will be easy as I'll be looking for anything I can to injure it. It need not necessarily be a stick, but just some kind of weapon...

The meaning is if you're already predisposed towards hating something you'll quickly find a way to destroy it.

If nothing like this exists feel free to say that and I'll try and find a way around it. I'd rather not shoehorn in an awkward translation.

Answer 1

This idiom does exist in English:

it is easy to find a stick to beat a dog

It is easy to attack (physically or verbally) a vulnerable person or thing. Primarily heard in UK.

I know it is easy to find a stick to beat a dog, but you need to stop criticizing your son—he's not being malicious, he's just a child!

https://idioms.thefreedictionary.com/it+is+easy+to+find+a+stick+to+beat+a+dog

Answer 2

C.S. Lewis wrote about the relative merits of two books by George Orwell: Animal Farm and 1984. He suggested in this connection that there was little reason for all of the attention to sexuality in the latter book; anti-sexual hostility seemed to be just one more vice which the author could attach to the bad guys.

But the principle that any stick is good enough to beat your villain with is fatal in fiction. Many a promising ‘bad character’ … has been spoiled by the addition of an inappropriate vice.

That saying seems similar an image similar to the one in your question. Lewis calls it a principle, perhaps suggesting that he considered it a familiar assumption. But it is not really a well-known saying today.