Yes, there is a type of foundation vent that you can use to permanently solve your problem. In fact, the reason they aren’t typically used is because they are a bit pricy. However, for a couple of dollars extra per vent you can lock these pesky animals out forever. Look for a “louvered” vent. This type vent is made of stamped galvanized sheet metal and is backed with a mesh screen. Even if larger animals could get through to the screen they would not be able get through the vent because the louver slots are too small. This can be screwed in directly over what you have already and will still allow for the proper ventilation of your home.