RESUMO
Weanling specific-pathogen-free rabbits were orally inoculated with 50,000 Ostertagia ostertagi 3rd-stage infective larvae cultured from bovine feces and were killed 42 days after inoculation. Two preliminary trials were done, using conventionally reared weanling rabbits inoculated with 2,500, 5,000, and 50,000 O ostertagi 3rd-stage larvae and dexamathasone in 1 of the trials; the rabbits were killed 14 and 28 days after inoculation. Fecal egg counts were monitored, and worm burdens were determined. The pH of the gastric contents was measured at necropsy. Recoveries of the parasite from the gastric mucosa comprised early 4th-stage larvae and larvae that had developed beyond the early 4th stage. The maximum worm burden established at 42 days after inoculation was 1,668 immature nematodes or 3.34% of the inoculum. Gross and microscopic gastric lesions were present. Gross nodular mucosal elevations, which tended to be confluent in the cardiac region, were observed. Microscopic changes were principally mucosal hyperplasia, focal lymphocyte accumulation with moderate glandular dilation, and slight variable eosinophil and plasma cell accumulation. The pathologic changes had characteristics similar to those in cattle infected with O ostertagi and other conditions characterized by gastric mucosal hyperplasia.
