Defects in collagen fibrillogenesis causing hyperextensible, fragile skin in dogs.
ABSTRACT Two unrelated mixed-breed dogs were donated for studies of their fragile, hyperextensible skin. Breeding of these dogs to bitches with normal skin showed that half of their male and female offspring also had fragile, hyperextensible skin, indicating that the defect was transmitted as an autosomal dominant trait in both dogs. Electron microscopy showed distinct abnormalities in the packing of collagen into fibrils and fibers in affected skin. These packing defects in dermal collagen were identical in related dogs, but were slightly different in unrelated animals. A clinical test, the skin extensibility index, was used to quantitate the extensibility of affected and unaffected skin. This index ranged from 8% to 15% in normal dogs and from 17% to 25% in newborn pups and adult dogs with collagen packing defects. The tensile strength of dorsolateral thoracic skin of affected pups was only 5% to 10% of that of matched specimens of paired littermates. The hyperextensibility and fragility of skin were the only clinical signs, but radiographic and microradiographic studies revealed subclinical involvement of bone.
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ABSTRACT: Defects in collagen proteins cause a variety of disorders in humans. It can be expected that collagen gene mutations are involved in collagenopathies in dogs. The collagen genes COL3A1, COL5A1, COL5A2, COL6A1, COL6A3, COL9A1, COL9A2, COL9A3, COL10A1 and COL11A1 were identified on the canine genome based on the homology with the human genes. Simple sequence repeats (microsatellites) were found in the chromosomal regions of these genes and investigated for polymorphism in Labrador Retrievers, Bernese Mountain dogs, Boxer dogs and German Shepherd dogs by PCR and subsequent detection of the DNA products. Nine informative microsatellite markers were identified. The markers closely situated to COL9A1, COL9A2 and COL9A3 were used to investigate the involvement of the genes in cranial cruciate ligament rupture in Boxer dogs. It was found that these genes are probably not involved in this abnormality. The markers described here will be useful for a candidate gene approach of suspected collagenopathies specific to dog breeds.Journal of Veterinary Medicine Series A 12/2007; 54(9):522-6. · 0.93 Impact Factor
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ABSTRACT: To describe the clinical, histological, and immunohistochemical manifestations of canine necrotizing scleritis. A retrospective examination of the clinical records and samples of ocular tissues from five dogs with a histological diagnosis 'necrotizing scleritis' was completed. Archived, formalin-fixed, paraffin-embedded samples and two control globes were stained with hematoxylin and eosin, Gram, periodic acid-Schiff (PAS) and Masson trichrome stains, and they were immunohistochemically labeled for CD3, CD18, and CD20. Of the five cases reviewed, only two could be confirmed as idiopathic necrotizing scleritis. The other three cases were retrospectively diagnosed as unilateral focal, non-necrotizing scleritis, one as episcleritis and the third was scleritis secondary to a proptosed globe based on our retrospective clinical, histological, and immunohistochemical evaluations. In these two cases, idiopathic necrotizing scleritis manifested as a bilateral, progressive, inflammatory disease of the sclera and cornea that induces significant uveitis. Light microscopic examination confirmed collagen degeneration and granulomatous inflammation. There was no evidence for an infectious etiology based on Gram's and PAS stainings. Immunohistochemical labeling revealed a predominance of B cells in idiopathic, bilateral necrotizing scleritis. Tinctorial staining abnormalities with Masson's trichrome stain were present in scleral collagen of the two cases with idiopathic necrotizing scleritis as well as a case of secondary traumatic scleritis. Based on a limited number of cases, idiopathic canine necrotizing scleritis shares similar histopathological features with non-necrotizing scleritis and episcleritis; however, necrotizing scleritis is B-cell-dominated and bilateral, and significant collagen alterations manifest with Masson's trichrome stain.Veterinary Ophthalmology 09/2011; 15(2):102-9. · 0.96 Impact Factor
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ABSTRACT: 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.Veterinary Dermatology 09/2004; 15(4):207-17. · 2.02 Impact Factor