Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
hirrĭo (irrio), īre, v. n., of dogs, to snarl: hirrire = garrire, quod genus vocis est canis rabiosae, Paul. ex Fest. p. 101 Müll. N. cr.; cf.: hirrit ὅταν κύων ἀπειλῇ ὑλακτῶν, Gloss. Philox.: veluti est canibus innatum, ut, etsi non latrant, tamen hirriant, Sid. Ep. 7, 3; Diom. 367 P.