In fact, there are many possibilities for this question, and the answer I give is:

8 chickens (16 legs); 2 ducks (4 legs); 10 goose (20 legs); 5 rabbits (20 legs); 10 dogs (40 legs)

16+4+20+20+40= 100

5 (rabbit) *2= 10 (goose)

2 (duck) *5= 10 (dog)

I forgot to take the first answer, thank you!