title: Esophageal Dysfunction in Friesian Horses: Morphological Features.
abstract: Megaesophagus appears to be more common in Friesian horses than in other breeds. A prevalence of approximately 2% was observed among Friesian horses presented to the Wolvega Equine Clinic and the Utrecht University Equine Clinic. In this study, morphologic changes in the esophagi of Friesian horses with megaesophagus were compared with those of 6 control horses. Of 18 horses with clinically observed megaesophagus, only 12 animals had esophageal dilation at necropsy, usually involving the thoracic portion. Muscular hypertrophy of the distal esophagus was present in only one-third of the affected horses, indicating that this change is not the most relevant cause of megaesophagus in Friesians. Increased deposition of clumped and disorganized collagen was present in these clinically affected horses mainly in the non-dilated portion of the esophagus. At necropsy, a decrease in neural elements and elastin was present principally in horses with megaesophagus. Mild degeneration and necrosis of the tunica muscularis along the entire length of the esophagus were present in clinically affected horses and encountered only rarely in control animals. There were no significant differences among affected and control horses with respect to inflammation, mineralization, or the number of cells of Cajal. The increased occurrence of megaesophagus in the Friesian breed compared with other horse breeds, together with the presence of abnormal collagen in very young foals, supports the hypothesis that megaesophagus is hereditary in Friesians.
authors.affiliation: Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands Margreet.Ploeg@uu.nl.
authors.forename: M
authors.initials: M
authors.lastname: Ploeg
authors.affiliation: Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Gröne
authors.affiliation: Laboratory of Veterinary Pathology, Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Saey
authors.affiliation: Wolvega Equine Hospital, Oldeholtpade, the Netherlands.
authors.forename: C M
authors.initials: CM
authors.lastname: de Bruijn
authors.affiliation: Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: Back
authors.affiliation: Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
authors.forename: P R
authors.initials: PR
authors.lastname: van Weeren
authors.affiliation: Tierärzliche Klinik Domäne Karthaus, Weddern 16c, Dülmen, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Scheideman
authors.affiliation: Bosdreef Equine Clinic, Spelonckvaart, Moerbeke-Waas, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Picavet
authors.affiliation: Animal Breeding and Genomics Centre, Wageningen University and Research Centre, Wageningen, the Netherlands.
authors.forename: B J
authors.initials: BJ
authors.lastname: Ducro
authors.affiliation: Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: Wijnberg
authors.affiliation: Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Delesalle
mesh_terms: D000818:Animals; D004931:Esophageal Achalasia / Q000503:physiopathology / Q000662:veterinary*; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D006734:Horse Diseases / Q000503:physiopathology*; D006736:Horses; D006984:Hypertrophy / Q000662:veterinary; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D010641:Phenotype
keywords: Friesian; collagen; equine; esophageal muscular hypertrophy; esophagus; histology; megaesophagus; muscle