Note 1264 — PERSIUS.
Lewis Evans translation
Canina litera. All the commentators are agreed that this is the letter R, because the "burr" of the tongue in pronouncing it resembles the snarl of a dog (cf. Lucil., lib. i., fr. 22, "Irritata canis quod homo quam planius dicat"), but to whom the growl refers is a great question. It may be the surly answer of the great man's porter who has orders not to admit you, or the growl of the dog chained at his master's gate, who shares his master's antipathy to you; or again it may be taken, as by Gifford,
"This currish humor you extend too far, While every word growls with that hateful gnarr.
Lubinus explains it, "Great men are always irritable; and therefore in their houses this sound is often heard."