remember that metronidazole is for flagellated parasitism or for gram positive and negative grown bacteria. one should use a true anti-parasite medication as a one - two time dose. ie panacur, pyrantel. some snakes are natural carriers of certain types of internal parasites as well as intestinal lining bacteria. its usually an issue if the immune system is suppressed for some other illness and any one of these parastes or bacteria begin to overgrowth due to a supressed immune system. generally, unless you see signs or symptoms of an overgrowth, you shouldnt have to treat. signs such as, diarrhea, regurge, and weight loss