What was the deal with Aberforth Dumbledore’s goat charm conviction?

I feel like it was supposed to be a throwaway joke originally, but then later in the series Dumbledore’s family backstory gets really dark and adult. But the key event in Aberforth’s life is still this apparently serious criminal conviction for… practicing unnatural charms on a goat?

What the hell was he doing to that goat? Initially it sounded like it was a sex thing—was he doing sex magic to the goat? That doesn’t really fit with his later character, as it’s presented; he’s supposed to be kind of beaten down by life and broken by his sister’s fate. How does that lead a man down a path to illegal goat sex practices?

I don’t get the impression that wizarding animal cruelty laws are especially progressive; they’re always transforming pretty large vertebrates into different household objects or whatever and it seems fine. So whatever Aberforth did to that goat must have been really heinous.