About 2 weeks ago we brought about 25 heifer home to be bred.  A couple days later we found one dead.  A few days later another one.  Then a few days later we noticed a very unenergetic heifer laying in the freestall.   Checked her out and she had pneumonia.  Treated her with draxxin and banimine.  She bounced right back. 

Then over the last ten days milking cows have been coming down with it.   9 out of 220 milking at last count have been treated for pneumonia.  Seems like every day it another one.  Treat them with nuflur and banimine.  Seems to be working.  It is a cross section of all cows, some fresh some 100 days in milk, some pregnant and almost ready to dry off.   We have a modern 6 row freestall barn with 14 foot sidewalls.   We did have the curtains closed, but the sidewalls curtains where down about 2 feet from the top, plus you have the eave open at all time of about 8 inches.  and we have a big ridge vent.

I call the vet out to check things out, he said open the barn up.  I find it hard to belive that in a barn like that they cant be getting enought ventatlation.  We dropped the top curtain all the way on the wind side and opened the south side up all the way.  He is reccomending to go throught the whole herd with Naselgen, or TSV2. 

Any recomendations??  Anybody else having and problems??  We are in Maryland by the way.