Metronidazole for dogs

Has anybody given their dog this medicine? I've looked it up online and it seems kind of "iffy". I am going to discontinue giving Fenway it. I gave him a 1/2 pill tonight and he's just laying around, not his old self. I'm going to call the vet tomorrow to let them know I won't be giving Fenway anymore.

He was prescribed it because he kept licking and looking at his butt and they "thought" he MAY have a parasite (though they couldn't find anything). They're doing a fiscal test tomorrow.

Thanks for any info you can give me.

I have heard really good things about it for fish, but haven't heard much about it for dogs.
Did they check the anal glands? Ususally that's the cause of dogs licking their bum.

I agree, most likely are
- impacted anal glands
- parasite, a regular worming will address that

They checked his glands and the vet said they appeared normal (not impacted). I don't know how they check for worms but they didn't think he had any. Maybe by a fecal test? They'll be doing that test tomorrow and calling me with the results.

Thanks for the advice!