Hereditary equine regional dermal asthenia ("hyperelastosis cutis") in 50 horses: clinical, histological, immunohistological and ultrastructural findings.
Data on fifty horses with hereditary equine regional dermal asthenia (HERDA; "hyperelastosis cutis") were collected on clinical, histopathological, ultrastructural and immunohistological findings. All horses were Quarter horses or of Quarter horse ancestry. Pedigree evaluation strongly supported an autosomal recessive mode of inheritance. The most common lesions were seromas/haematomas, open wounds, sloughing skin, and loose, easily tented skin that did not return to its initial position. Definitive diagnosis could not be made via histopathology, although the presence of tightly grouped thin and shortened collagen fibres arranged in clusters in the deep dermis was suggestive of the disease. Trichrome, acid orcein-Giemsa and immunohistochemical stains for collagens I and III showed no consistent abnormalities compared to control horses; an increase in elastic fibres was not a consistent finding. Electron microscopy showed no abnormalities in the periodicity of the collagen bundles; neither orientation nor variation of cross-section diameter of the collagen fibrils differentiated control from affected horses. The diagnosis of HERDA relies on clinical presentation, but may be supported by suggestive (although not pathognomonic) histopathological lesions.
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. sdwhite@ucdavis.edu
Stephen D
SD
White
Verena K
VK
Affolter
Danika L
DL
Bannasch
Patricia C
PC
Schultheiss
Dwayne W
DW
Hamar
Phillip L
PL
Chapman
Diane
D
Naydan
Sharon J
SJ
Spier
Rod A W
RA
Rosychuk
Christine
C
Rees
Gregg O
GO
Veneklasen
Alondra
A
Martin
Diane
D
Bevier
Hilary A
HA
Jackson
Sonya
S
Bettenay
Jennifer
J
Matousek
Karen L
KL
Campbell
Peter J
PJ
Ihrke
D000818:Animals; D015331:Cohort Studies; D003937:Diagnosis, Differential; D004535:Ehlers-Danlos Syndrome / Q000175:diagnosis / Q000662:veterinary*; D005260:Female; D020022:Genetic Predisposition to Disease; D006734:Horse Diseases / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D010375:Pedigree; D011446:Prospective Studies; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology / Q000648:ultrastructure