Date of Award

1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

European-type mixed-breed goat kids were infected with Ostertagia ostertagi or were given chronic pentagastrin treatment. Selected clinicopathological parameters and fecal egg counts were monitored throughout the study. At necropsy the abomasal physical parameters were recorded and tissue samples were saved for parasite recovery, quantitative and qualitative light microscopy and transmission and scanning electron microscopy. Serum pepsinogen and gastrin immunoreactivity increased in parasitized animals. The increase was associated with the tissue phase of the parasitic development. Pentagastrin did not alter pepsinogen or gastrin immunoreactivity. All 8 infected animals had patent infection, and approximately 5% establishment of the infective dose of 15,000 O ostertagi was achieved. The majority of the recovered parasites were adult and approximately 60% of them were female. At the time of necropsy the O ostertagi-infected animals had increased abomasal pH and the abomasa of the parasitized and the pentagastrin-treated animals had slightly increased weight. The abomasal mucosa of infected animals had umbilicated, white, raised nodules as has been described in bovine ostertagiasis. Pentagastrin-treated animals had prominent fundic folds. The light microscopic morphology of infected goats was similar to that of the bovine disease. There was a significant increase in the abomasal mucosal thickness, primarily due to the proliferation of mucous cells. The majority of the proliferating mucous cells contained sialoor sulfomucins. In pentagastrin-treated animals only slight thickening of the mucosa occurred. The transmission electron microscopic findings in parasitized animals were similar to bovine ostertagiasis, although there was no striking separation of the lateral plasmalemmata. In pentagastrin-treated animals the parietal cells appeared active and had abundant intracytoplasmic canaliculi lined by long microvilli. Scanning electron microscopy revealed marked surface alterations in hypertrophic parasitized abomasa, while control and pentagastrin treated animals had morphology similar to other mammals. Goats infected with O ostertagi developed a hypertrophic abomasitis. Hormonal factors appeared to be associated with the development of abomasal changes. Pentagastrin did not have a significant effect on the caprine abomasum. Slight subcellular changes and slight hyperplastic changes occurred.

Pages

189

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