CompGraphicByStyle allows an animal to be affected by an ideoligion style, as usually pawns are not affected by styles, only buildings and other items.

    public List<StyleGraphics> styleGraphics;
    public int changeGraphicsInterval = 2000;

StyleGraphics is as follows:

    public StyleCategoryDef style;
    public string styleImageSuffix;

It is a comp class, so you just add it in XML in the <comps> tag of the animal you want to be change styles.

You'll also need to add a PawnRenderNode to the animal, AnimalBehaviours.PawnRenderNode_GraphicByStyle