Before splitting his soul or becoming the dark wizard that he was, he was a young normal boy. He must have had some form of patronus and I too think it would be a snake...

He could have or might have not had one. As what Dumbledore said in Deathly Hallows, "That which Voldemort does not value, he takes no trouble to comprehend." Perhaps he could have been capable of conjuring up a patronus, but he never really cared to learn how or even understand what a patronus is coz to him, it is of no worth or significance.

He was not interested in defending magic. He was a murderer, an attacker a dark wizard. He had no need, not at Hogwarts and not later. Never.

He wasn't able to preform one.

He didn't need one, with the dementors as his Allies.

Most people don't have patronuses. They are very complicated magic. I don't think Voldemort would have had any really happy memories to draw on, even before he split his soul.

I would most likely think it is a snake when he was in Hogwarts

@icecreamdif plural is Patroni by the way. Same like Animagi 😉 but I totally agree with what you said of course. Good point!

Thanks

He didn't have one. To produce one, you have to have a happy memory in mind. I don't think he had many happy memory's.