Do humans respect viagra enough? Methinks, not: There is an iguana who now is in danger of having his penis amputated after innocently consuming viagra. Yeow! It's a good thing that iguanas have hemipenes instead of one penis.
Mozart, an iguana with an erection that has lasted for over a week, will have his penis amputated in the next couple of days.
Mozart, sitting on the shoulders of his keeper as camera crews focused on his red, swollen erection, seemed unperturbed by the news.
Cited story.
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Iguanas have penises??? I thought they only had cloacas. Is that common among reptiles?
PZ has written an article on Pene Evolution . You might find that helpful.
In any case - I fear GS is half wrong; it seems to me Sildenafil would most likely result in erection of both hemipenes, and the iguana will lose both of them. The reporter probably referred the singular due to confusion.