Toxic substance pneumonia revisited

What is atypical interstitial pneumonia of cattle?
- necrosis of type I pneumocytes
- edema, respiratory distress
- replacement of type I pneumocytes by type II pneumocytes
- septal fibrosis and eventually emphysema

How do cattle get atypical interstitial pneumonia?
- if they eat feed rich in L-tryptophan
- L-tryptophan is converted to 3-methyl indole in the rumen
- Clara cells convert 3-methyl indole to a cytotoxin, resulting in necrosis of type I pneumocytes

Certain plants can be pneumotoxic to cattle: for example, the sweet potato vine, which produces a mycotoxin called ipomeanol. Results are similar to atypical interstitial pneumonia.


There are toxic gases.
What type of toxic gases are we talking?

• nitrogen dioxide
• hydrogen sulfate (derived from bacterial growth on manure)
• ammonia (derived from bacterial growth on urine, manure; causes ciliostasis and loss of cilia, a.k.a. ciliocyophthoria)
• ozone (irritant)
• sulfur dioxide (irritant)
• carbon monoxide (not a pneumotoxin, but causes formation of carboxyhemoglobin, which results in hypoxia)
• volatile fluoropolymers (e.g. overheated Teflon; cause death by peracute pulmonary hemorrhage)