I found a bug...

[flyinghammy]

I created the listen to animal spell first before I plucked the cat hair. When I got the cat hair after the spell then I received 0 points.

[Erpy]

You only get 0 points if you've made the animal language spell using the cat hair and also picked up the dog hair before getting more cat hair. It's intentional.

[flyinghammy]

I recalled I used the dog hair for the spell and never picked up the cat hair until after I completed the spell. I received 0 points for the cat hair, which I don't think it's the game's intention. I can recreate this issue.

[Erpy]

In that case, it's a bug. I'll look into it.