I soak them in the bathtub in hot bleach water solution, rinse them well, and then let them dry out in the sunshine. I use an old toothbrush to scrub the plastic mesh The pee smell is still present, but this helps a lot. If you do this, use a 10% bleach solution, and rinse it very well.
What I have discovered is, that amount that I use the trimmers and need to clean them, the stitching starts to fall apart pretty quickly. My hubby and I are trying to come up with an alternative solution that I can sell with the Wodents on my site...so far, I got nothin' any different from what's already out there.