I am going to try and make this as short as possible. I am heartbroken right now and on a search for as much information about this nasty disease as possible. But that appears to be an uphill battle as there is not much out there besides repeat information.
We adopted our first dog on 12/09/2017. She was an 8 year old terrier mix. The best dog ever. She came to us fully trained and was a gentle soul. All she wanted was the wedge of our couch, some good eats and a few belly rubs during the day. We thought we landed the jackpot of perfect first dogs.
About a week after we brought her home, she began to get picky with eating. Only nibbling here and there on her food. She then got sick with what appeared to be an upper respiratory infection. Symptoms included fever, loss of appetite, lethargy, cough and eye/nose discharge. It was a very stubborn infection that would not clear up. After many trips to the vet (often consecutive days in a row), many medications, repeats of X-rays, blood work and other tests, second and third opinions, we finally got a diagnosis and a plan of action. Unfortunately, that diagnosis came on the same day that her body just could not keep fighting off the infection on its own and we lost her. She passed on 03/01/2018. We didn't even get 3 months with her.

I guess my question is, how could I have prevented this? What did I do to allow this to happen?
She was mainly and indoor dog. We just went outside for bathroom breaks and maybe a short walk.
No hunting, no woods, no water. Could she have possibly came to our home already with the fungus, and it was just a matter of time for the attack?
My kids are heartbroken. They have begged us for years for a dog. We finally found the perfect dog and then this happens.