CHARACTERIZATION OF INTESTINAL MORPHOLOGIC, BIOCHEMICAL, AND ULTRASTRUCTURAL FEATURES IN GLUTEN-SENSITIVE IRISH SETTERS DURING CONTROLLED ORAL GLUTEN CHALLENGE EXPOSURE AFTER WEANING

OBJECTIVE: To characterize histologic, biochemical, and ultrastructural changes in the intestine of Irish Setters susceptible to gluten-sensitive enteropathy (GSE) during controlled oral challenge exposure with gluten after weaning. ANIMALS: Six gluten-sensitive and 12 healthy Irish Setters and 3 healthy Greyhounds. PROCEDURE: Jejunal biopsy specimens were taken at 4 and 12 months of age from the 6 gluten-sensitive Irish Setters, which had been reared on a gluten-free diet to which a controlled dose of gluten (0.5 g/kg of body weight/d) was added. Control specimens were obtained at 4 (n = 5) and 12 (7) months of age from the healthy Irish Setters, which had been fed a conventional gluten-containing diet, and at 4 months of age from the healthy Greyhounds fed the controlled dose of gluten. The specimens were subjected to histologic and ultrastructural examinations and assay of brush border enzymes. RESULTS: Gluten-sensitive Irish Setters developed abnormalities characteristic of GSE at 4 months. Abnormalities were comparable to changes not seen previously until 12 months in dogs with GSE fed a conventional gluten-containing diet. In addition, microvilli were stunted and irregular, and a few were vesiculated and reduced in number; the glycocalyx was reduced or absent. By 12 months of age, there was improvement in morphologic and biochemical parameters, indicating partial recovery despite continued exposure to gluten. CONCLUSIONS: Relative early onset of intestinal damage, compared with that previously reported, and subsequent partial recovery suggestive of oral tolerance to gluten may be attributable to oral administration of gluten as a purified extract rather than in dietary cereal, but alternative explanations include differences in environment or genetic susceptibility to gluten.