Re: So the EMH Never Heard of the Dominion
As for programming the EMH to deal with Jem'Hadar weaponry, I don't think Starfleet would know anything about such things yet. Nobody had been hit by Jem'Hadar light arms in "Jem'Hadar", and none of their weapons had been captured. In contrast, their ships had been in combat with Starfleet assets that had survived, so it's not unexpected that Paris in "Parturition" would have access to a crude simulation of Dominion ships.
What's known for sure is that the idea of Jem'Hadar weapons leaving an anticoagulant behind wasn't discussed until the fifth season, so that definitely wouldn't have made it into Voyager's database unless Starfleet provided Voyager
with new information in their care package sent after "Message in a Bottle."
"Many things seem clever to an imbecile." --Captain Thelin th'Valrass, USS Enterprise-- "The Chimes at Midnight"