Animal part of our soul?

No such thing.
Man consists of two essential parts–a material body and a spiritual soul. The rational soul is per se the essential form of the body. Every individual soul was immediately created out of nothing by God. Sanctifying Grace is a created supernatural gift really distinct from God. Sanctifying grace sanctifies the soul, and it bestows supernatural beauty on the soul.
Aquinas, in Summa contra Gentiles, proves:
- the perfection of the universe required the existence of some intellectual creatures endowed with will and having freedom of choice in acting;
- the intellectual substance is not a body, is immaterial, is incorruptible, and is united to the body without intermediation;
- the whole soul is in the whole body and in each of its parts;
- the souls of brute animals are not immortal, but the human soul begins to exist when the body does, brought into being through the creative action of God, and it does not perish when the body is corrupted;
In the Catechism we read:
Effect of sin in the soul: