Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
2. porrīgo, ĭnis, f., the scurf, dandruff on the head, Cels. 6, 2; Plin. 20, 6, 23, § 53; 20, 6, 27, § 69; 28, 11, 46, § 163; 32, 4, 14, § 35; Hor. S. 2, 3, 126.
Also of other hairy parts of the body, Scrib. Larg. 243.
Of animals, perhaps the mange: porci, Juv. 2, 80.