Cat's Ears

If you're cat in an in- and outdoor cat and has been exposed to other animals with ear mites, then it's possible for him to have them. Two common signs are scratching at the ears and dark, somewhat dry debris. If that's what you're seeing then you could try treating his ears with a natural or prescription mite medication. If you don't get a response after following the instructions to the letter--it can take time to get rid of mites--then have your cat checked by your veterinarian. There are some ear infections, such as those caused by certain yeast organisms, that also produce a dark discharge.

I agree with Dr. Myrna here. You may also want to consider a different diet for your cat, one that will build his immune system naturally and be able to fend off these sort of pests naturally. Cats are obligate carnivores so considering a raw diet will help him a lot.

You can find out more at www.rawfedcats.org

Ther are also natural ear remedies that can help

http://www.earthclinic.com/Pets/ear_mites.html