Nicole

“I'm afraid they're not very well-designed creatures, dragons."
Vimes listened.
"They would never have survived at all except that their home swamps were isolated and short of predators. Not that a dragon made good eating,
anyway-once you'd taken away the leathery skin and the enormous flight muscles, what was left must have been like biting into a badly-run chemical factory. No wonder dragons were always ill. They relied on permanent stomach trouble for supplies of fuel. Most of their brain power was taken up with controlling the complexities of then-digestion, which could distill flame-producing fuels from the most unlikely ingredients. They could even rearrange their internal plumbing overnight to deal with difficult processes. They lived on a chemical knife-edge the whole time. One misplaced hiccup and they were geography.
And when it came to choosing nesting sites, the females had all the common sense and mothering instinct of a brick."
Vimes wondered why people had been so worried about dragons in the olden days. If there was one in a cave near you, all you had to do was wait until it self-ignited, blew itself up, or died of acute indigestion.”
― Terry Pratchett, Guards! Guards!