You can use the CSS :hover pseudo classes in SVG. You just need to define the CSS styles inside the SVG - or reference the CSS file from within the SVG.
See this question for an example: How to hover over an SVG rect?
If, for some reason, you can't edit the original SVG files, you could add a style element dynamically after loading. You could also do it by adding pointer events (onmouseover/onmouseout).