It turns out Ryoga is also a victim of Jusenkyo, turning into a baby pig every time he is splashed with cold water. Akane, who does not yet know this, vows to keep the piglet and let it sleep in her bed. When Ranma hears this...
Ranma learns that the black piglet found by Akane is Ryoga. What's more is that Ranma learned he unknowingly knocked Ryoga into the Spring of Drown Pig during his visit to Jusenkyo. Which is why Ryoga has such a grudge against Ranma. As Ryoga is cursed to become a piglet every time he encounters cold water. This wouldn't be so bad, until Akane decided to adopt the pig form of Ryoga not knowing it's actually Ranma's enemy.—J LeGault