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  • Author or Editor: Yosiya Niyo x
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in Journal of the American Veterinary Medical Association

Summary

Microscopic examination of the nasal mucosa of clinically normal specific-pathogen-free pigs and of toxicogenic type-D Pasteurella multocida toxin challenge-exposed_ specific-pathogen-free pigs indicated that the surface epithelium in pigs of both groups was microscopically normal; erosions or appreciable inflammatory changes were not evident. In pigs of both groups and in all 3 regions of the nasal cavity, the endothelial lining of all blood vessels appeared normal without detectable changes to the walls at postinoculation day 10. Vascular injury in the cartilage or the bone was not discernible in control or challenge-exposed pigs.

There were marked differences in the osseous structures of the conchae when the 2 groups were compared. In control pigs, active bone formation and remodeling were observed, and the septal cartilage was normal. In toxin challenge-exposed pigs, there likewise was normal bone formation and remodeling in the vestibular region, and the septal cartilage was normal. In marked contrast, conspicuous changes were observed in the osseous core of the conchae of the respiratory and, sometimes, the olfactory regions. These changes consisted of bone necrosis and resorption by large numbers of osteoclasts with variable replacement by dense mesenchymal stroma, which resulted in conchal atrophy. In the absence of any discernible damage or injury (angiopathy) to the nasal vessels, it appears that the action of the dermonecrotoxin of P multocida serotype D is on the most active osteoblasts and the associated organic matrix of the bone, with subsequent disruption of normal bone formation and remodeling of the nasal conchae.

Free access
in American Journal of Veterinary Research

SUMMARY

Plasma concentrations of porcine growth hormone (pgh) were similar in healthy pigs and those with atrophic rhinitis (ar), therefore, observed reduced growth rates and feed efficiency in naturally infected pigs with ar were not attributed to low concentrations of plasma pgh. Also, pituitary glands in both groups of pigs were responsive to growth hormone-releasing hormone (ghrh) challenge by increasing pgh secretion. Administration of clonidine hydrochloride to pigs naturally infected with ar failed to elicit any significant change (5.3 ± 1.4 ng/ml) in the plasma concentration of pgh within a 45-minute bleeding interval. The pretreatment concentrations of pgh were similar in specific-pathogen-free toxin-treated and specific-pathogen-free control groups, but they increased significantly in toxin-treated pigs (20.7 ± 8.2 ng/ml) within 15 minutes after ghrh injection. Porcine growth hormone release in toxin-treated pigs was variable; however, all pigs did not respond to ghrh administration: 3 responded with an increase in pgh release (35.6 ± 10.6 ng/ml), 2 did not respond (6.7 ± 0.5 ng/ml), and 1 had a decrease in pgh release (3.9 ng/ml).

Therefore, the observed reduced growth rates reported in the literature may be attributed to factors at the target level of pgh action, such as insufficient or down-regulation of pgh receptors, changes or impaired ability in the pgh receptor-binding characteristics, and inability of pgh receptor complex to transduce signal. Toxins are known to modulate signal transduction pathways. It has been speculated that serotype-D Pasteurella multocida toxin may influence growth by its effect on signal transduction from pgh receptor complex on the cell membrane to the interior of the cell. This would account for the presence of high concentrations of pgh in the plasma and a functionally competent hypophysis cerebri, which responded to ghrh injection that have retarded growth in pigs affected with ar.

Free access
in American Journal of Veterinary Research

Objective—

To evaluate lavage analytes as markers of mucosal inflammation in healthy dogs and dogs with inflammatory bowel disease (IBD).

Design—

Case control study.

Animals—

9 healthy dogs and 10 dogs with IBD.

Procedure—

A polyethylene glycol electrolyte solution was administered into the dogs’colons via a rectal balloon catheter prior to colonoscopy. Lavage solution was allowed to remain intraluminally for 30 minutes and then was withdrawn. Lavage supernatant samples were immediately analyzed for total protein, IgG, and nitrite concentrations and myeloperoxidase activity. Mucosal biopsy specimens were obtained from the descending colon and histologically reviewed.

Results—

All dogs with IBD had mild to severe lymphocytic-plasmacytic colitis, whereas 8 of 9 healthy dogs did not have substantial mucosal inflammation. Myeloperoxidase activity was not detected in lavage samples from healthy dogs or dogs with IBD. Total protein concentration was not significantly different between groups. Mean nitrite and IgG concentrations were significantly higher in samples from dogs with IBD (1.83 nmol/ml and 46 mg/dl, respectively), compared with samples from healthy dogs (0.245 nmol/ml and undetectable concentrations, respectively). Severity of lesions was not correlated with nitrite or IgG concentration.

Clinical Implications—

Assay of nitrite and IgG concentrations in colonic lavage fluid Is a simple, objective means of evaluating mucosal inflammation in dogs with IBD. Potential uses include monitoring response to treatment and evaluation of complex cases of chronic intestinal inflammation. (J Am Vet Med Assoc 1997;211:318–321)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To quantitate immunoglobulin-containing cells (IgA, IgG, and IgM) and CD3+ T cells in colonic biopsy specimens obtained from dogs with lymphocytic-plasmacytic colitis (LPC), and to compare lymphocyte and plasma cell populations in dogs with LPC with those in healthy dogs.

Animals

10 healthy dogs and 11 dogs with LPC.

Procedure

Colonic mucosal specimens obtained from healthy dogs and dogs with LPC were stained specifically for IgA-, IgG-, and IgM-containing cells and CD3+ T cells by use of immunoperoxidase techniques. Morphometric analyses were done to quantitate lymphocytes and plasma cells in standardized areas of colonic mucosa. Data analyses allowed determination of mean cell numbers in each dog group, and comparison of mean numbers of lymphocytes and plasma cells between dog groups.

Results

CD3+ T cells predominated in healthy dogs, whereas CD3+ T cells and IgA-containing cells were most numerous in dogs with LPC. In both dog groups, the IgG- and IgM-containing cells were considerably less numerous than the other 2 cell types. Comparison of cell populations between dog groups indicated that IgA- and IgG-containing cells and CD3+ T cells were significantly more numerous in the colonic mucosa of dogs with LPC.

Conclusions

Dogs with LPC have significantly increased numbers of IgA- and IgG-containing cells and CD3+ T cells. These lymphocyte and plasma cell distributions indicate similarities to and differences from such distributions in human beings with inflammatory bowel disease. Results provide a basis for future correlation between histologic stage of disease activity and immunologic findings in dogs with LPC. (Am J Vet Res 1999;60:515-520)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To quantitate numbers of immunoglobulin (Ig)-containing cells (IgA, IgG, and IgM) and T cells (CD3+, CD4+, and CD8+) in the colonic mucosa of healthy dogs, and to determine whether mean cell numbers differ among colonic regions.

Animals

10 clinically normal young adult mixed-breed dogs.

Procedure

Endoscopically obtained specimens of ascending, transverse, and descending colonic mucosa were stained specifically for IgA, IgG, and IgM heavy chains and T-cell antigens, CD3+, CD4+, and CD8+, using immunoperoxidase techniques. Morphometric analysis, performed by light microscopy, was used to quantitate numbers in these standardized areas of colonic mucosa. Data analysis allowed determination of mean cell numbers in each colonic region, as well as comparison of mean cell numbers among colonic regions.

Results

The CD3+ and CD8+ T cells were the predominant immune cell types in all colonic regions. In the mucosa, CD3+ T cells were significantly (P < 0.05) more numerous than CD8+ T cells, and CD8+ T cells were significantly (P < 0.05) more numerous than CD4+ T cells. The IgA-containing cells were significantly (P < 0.05) more numerous than IgG-containing cells, whereas IgM-containing cells were least numerous (P < 0.05). Differences in mean cell counts among colonic regions were not significant for Ig-containing cells or T cells.

Conclusions

Mean numbers of immune cells did not differ significantly among colonic regions in healthy dogs, although differences existed in mean populations of T cells and Ig-containing cells. The CD3+ and CD8+ T cells were the most numerous immune cell types in colonic mucosa.

Clinical Relevance

These quantitative data provide a basis for study of alterations in populations of mucosal immune cells and their possible contribution to the pathogenesis of gastrointestinal tract disease. (Am J Vet Res 1998;59:552–556)

Free access
in American Journal of Veterinary Research