Wow!,.......I've seen a pretty good number of Spilotes pullatus, and I've NEVER seen one that comes close to that!
* Does the feces look normal?
* Can you see his body moving up and down smoothly as he breathes?....do you hear anything during this?
* Does the snake feel as heavy as he looks?
I have never seen, or heard of a respiratory problem that made the animal seem to "grow" like that in my 40 years of snake experience either.
If the snake does indeed feel very heavy from mass, and not "hollow" from being filled with air,....and all the other things noted above seem to be okay,....I guess it really could be just a simple case of obesity,.....that surely would be an under-statement though!..hahaha..........keep us posted about this.
I would keep a close eye on the stools to see if he's passing what he's ingesting.
best regards, ~Doug
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"Better to be silent and thought a fool, than to open mouth and remove any doubt!"