I'm late to the party but stumbled upon this thread. I just had the OptiSpot test done on my rat Pogo after fighting what has felt like an ongoing battle of resistant respiratory troubles this year. Pogo, Minca, and Bean have all been having intermittent stuffiness attacks, and both mice I brought in had respiratory noises that did not respond to abs (one finally died of respiratory issues). I had planned to test Minca but she got cancer and was deemed a less likely candidate for testing, and while Pogo had arrived to me with bad respiratory issues he became the next best candidate because his issues are more consistent.
The test itself ran me about $200 and results took about two weeks. She attempted to get blood from the tail, but not enough would come out so I believe she used a back leg vein. I should have emailed results Monday and I'd be happy to post those here if it provides any information for anyone. I was told he tested positive for Myco, some form of bacteria that affects the cilia (the name did not sound familiar to me), and two strains of bacteria that are more common with mice instead of rats. I was also told that most of what he tested positive for was more commonly spread via direct contact, and more responsive to the sulfa antibiotics.
Personally, it was worth it to me to have the test done to simply know "what" we've been fighting, as it's pretty much felt like we're working blind and respiratory illnesses break my heart to watch. I'm told we'll stick with the doxy/cerenia course of antibiotics he's on, as they seem to be working for now, and later if anyone regresses we'll move onto the sulfas.