Rat died from fungus in lungs

Question
My rat got sick last month and had trouble with pneumonia coming and going till finally we put him down a few days ago.
The vet did an autopsy and results were in today saying she had a fungus in the lungs. What is that? I heard of myco but a fungus in the lungs? Does my vet know what he is talking about?

Answer
Hi Paulina

Wow!! You have no idea how sorry I am about the loss of your little rat, especially to this terrible form of pneumonia.
Tell me, is your vet an exotic vet? It seems to me that he has sent tissue samples out to pathology after the necropsy so it was not your vet that read the results, it was the pathologist and I highly doubt there was error in that case.
The fungal infection you are talking about is Pneumocystis which can indeed involve the lungs. It is a slow progressing disease that, when involving the lungs, can create respiratory infections and weight loss, along with other common symptoms much like that of bacterial pneumonia.
The thing is, your little girl must have had a serious secondary infection or perhaps was given steroids without antibiotics or something that caused her immune system to become so weak because usually a rat with a severely depressed immune system is open to something as serious as pneumocystis pneumonia.  Did she have chronic mycoplasmosis infections or other secondary infections prior to this?

To sum it all up and answer your question: No, you do not need to question your vet and his diagnosis mainly because he is simply going by the necropsy results from pathology and also, what claimed your rats life is a deadly illness and not much could have been done to save her really, only prolong the illness by keeping her alive.

I am really sorry...

Sandy