I keep coming back to this thread because my heart just breaks for you, Blann, and his sisters. And, I keep reading and reading, but without being a vet myself, my responses are informed guesses at best.
Everything I've read points to this being a fungal infection -- especially since Blann's sisters are also starting to show similar symptoms. And, since your vet immediately thought histoplasmosis, I think that is the best, and most likely, place to start. I've done some reading on other fungal infections commonly (or, perhaps, uncommonly) seen in felines and they do not match the symptoms. Aspergillosis affects the nasal cavity most frequently, sporotrichosis affects the skin, toxoplasmosis doesn't fit the symptoms, and the list goes on. Histoplasmosis is the one thing I've found so far that really makes sense. But, with a negative test result, well, it had me researching...again.
Do you know what tests were done when looking for the histoplasmosis infection? From what I've read, it appears that there are a number of different ways to test for the fungal infection and that there is some probability of false negatives. There is a lot to share here about the types of tests done and their possible results, so here is the link I am working off of: http://veterinarymedicine.dvm360.com...date=&pageID=7. I've looked at numerous sites, but this one has been the most helpful by far. It provides the most throrough, in-depth information that I've been able to find to date and explains things well. Hopefully, it will be of help to you as well.
Has Blann gone through the tracheal wash as of yet? I'm curious to learn of the findings and also to hear that he has come through the procedure okay. I can't imagine how difficult this has been for you
. Please keep us updated on how Blann and his sisters are doing.
Everything I've read points to this being a fungal infection -- especially since Blann's sisters are also starting to show similar symptoms. And, since your vet immediately thought histoplasmosis, I think that is the best, and most likely, place to start. I've done some reading on other fungal infections commonly (or, perhaps, uncommonly) seen in felines and they do not match the symptoms. Aspergillosis affects the nasal cavity most frequently, sporotrichosis affects the skin, toxoplasmosis doesn't fit the symptoms, and the list goes on. Histoplasmosis is the one thing I've found so far that really makes sense. But, with a negative test result, well, it had me researching...again.
Do you know what tests were done when looking for the histoplasmosis infection? From what I've read, it appears that there are a number of different ways to test for the fungal infection and that there is some probability of false negatives. There is a lot to share here about the types of tests done and their possible results, so here is the link I am working off of: http://veterinarymedicine.dvm360.com...date=&pageID=7. I've looked at numerous sites, but this one has been the most helpful by far. It provides the most throrough, in-depth information that I've been able to find to date and explains things well. Hopefully, it will be of help to you as well.
Has Blann gone through the tracheal wash as of yet? I'm curious to learn of the findings and also to hear that he has come through the procedure okay. I can't imagine how difficult this has been for you