Evaluation of pituitary gland anatomy and histopathologic findings in clinically normal horses and horses and ponies with pituitary pars intermedia adenoma

To determine size and weight of the pituitary gland and associations between pituitary gland size and weight and sex and age in horses without clinical signs associated with pituitary pars intermedia adenoma (PPIA) and horses and ponies with PPIA. Pituitary glands from 100 horses without clinical si...

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Bibliographic Details
Published in:	American journal of veterinary research Vol. 65; no. 12; pp. 1701 - 1707
Main Authors:	Kolk, J.H. van der, Heinrichs, M, van Amerongen, J.D, Stooker, R.C.J, in de Wal, L.J, van den Ingh, T.S.G.A.M
Format:	Journal Article
Language:	English
Published:	United States 01-12-2004
Subjects:	adenoma Adenoma - pathology Adenoma - veterinary Adrenocorticotropic Hormone - blood Age Factors animal age animal morphology Animals blood glucose Blood Glucose - analysis body weight corticotropin cortisol Female gender differences histopathology horse diseases Horse Diseases - pathology Horses Hydrocortisone - blood hyperplasia insulin Insulin - blood lesions (animal) Male Organ Size pituitary gland Pituitary Gland - anatomy & histology Pituitary Gland - pathology Pituitary Neoplasms - pathology Pituitary Neoplasms - veterinary pituitary pars intermedia adenoma tissue weight
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Summary:	To determine size and weight of the pituitary gland and associations between pituitary gland size and weight and sex and age in horses without clinical signs associated with pituitary pars intermedia adenoma (PPIA) and horses and ponies with PPIA. Pituitary glands from 100 horses without clinical signs of PPIA and 19 horses and 17 ponies with PPIA. Pituitary glands were weighed, measured, and examined histologically by use of H&E stain. Masson trichrome and periodic acid-Schiff staining were used, when appropriate. Histologic lesions in the pars intermedia, pars distalis, or both were classified as no significant lesions, single or multiple cysts, focal or multifocal hyperplasia, single or multiple microadenomas, and adenoma. Relative pituitary weight (RPW) was calculated as pituitary weight (grams) divided by body weight (grams). There was an age-related increase in the presence of pituitary lesions in the pars distalis and pars intermedia in geldings, mares overall, and non-pregnant mares. Mean (+/-SD) RPW in horses with PPIA was not significantly different from ponies with PPIA (15+/-5.9 x 10(-6) and 16+/-72 x 10(-6), respectively). Maximum pituitary weight in a horse with PPIA was 13.9 g (RPW, 2.9 X 10(-5)). Plasma glucose concentration was positively correlated with RPW in ponies with PPIA. Pituitary lesions may be a factor in horses with insulin resistance and laminitis before development of clinical signs of PPIA. Ovarian steroids may be involved in the pathogenesis of lesions in the pars intermedia.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0002-9645 1943-5681
DOI:	10.2460/ajvr.2004.65.1701