Hyphenated in the OED entry.

• 13.046 and broken drinking-horns

I am struck that they are broken drinking horns – it helps me remember that the dragon isn’t a glorious creature who looks splendid in among the treasure, but that Tolkien’s dragons in Middle-earth are malicious and covetous.

[01.123]  Dragons… hardly know a good bit of work from a bad,

“drinking, n.” OED Online. Oxford University Press, June 2017. Web. 7 September 2017