Update:

It's been three weeks since starting the Tylan and all of the rats are thriving. No sneezing, everyone looks healthy, very active, eating and drinking well. Even the new babies are fat and happy and all the litters were large (16+). Females are pregnant so breeding is continuing.

The pet rats on Baytril and Doxy were better within a few days and are now back to normal. I do not think it was worth the money for those two medications. The Tylan would have done the same thing.

I think culling sped up the recovery of the entire colony. I also think that the Tylan 200 was a better choice than the Tylan 50. I mixed 3ml per gallon instead of the 2.5ml recommended. I will continue with the Tylan for another week (4 total).

I hope this thread helps. Thanks.