Howie, hepatitis is caused by a virus, so filtering would make no difference. However, the canine hepatitis virus is different from the ones which cause hepatitis in humans. There are also other conditions (some genetic) which cause the same symptoms.

Probably the most important preventive is keeping your dog current on his vaccines (canine hepatitis is part of the core vaccine package). Which reminds me that Hysson is due for his, and I'd better get on the phone to the vet!
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey