Fibrodysplasia ossificans

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Fibrodysplasia in a dog (left; normal) showing regular arrays of enlarged, active fibroblasts and bundles of relatively dense collagen replacing normal adipose tissue[1]

Fibrodysplasia ossificans is a rare skin disease of dogs characterized by connective tissue ossification.

This condition can occur as a result of metaplasia from calcinosis cutis and is thought to involve dysregulation of connective tissue matrix metalloproteinases[2]. Matrix metalloproteinase activity is implicated in a number of disease processes, including rheumatoid arthritis, osteoarthritis, osteoporosis, peridontal disease, metastatic tumorigenesis and neoplastic growth, aneurysm, atherosclerosis, and heart failure.

In dogs, a single case has been reported as body ossifications of the thoracic limbs, resulting in lameness and pannus formation.

Histological examination revealed physeal and subphyseal trabecular thickening, synovial hyperplasia and hypertrophy, pannus formation with lymphocyte infiltrates and fibrin within the joint space, fibrosis of perisynovial adipose tissue, and other soft tissue fibroplasias[1].

It was treated with surgical debridement of affected tissue[3].


  1. 1.0 1.1 Westwood R et al (2009) Characterization of fibrodysplasia in the dog following inhibition of metalloproteinases. Toxicol Pathol 37(7):860-872
  2. Tugwood JD et al (2012) Fibrodysplasia induced in dog skin by a matrix metalloproteinase (MMP) inhibitor--a mechanistic analysis. Toxicol Sci 127(1):236-245
  3. Guilliard MJ (2001) Fibrodysplasia ossificans in a German shepherd dog. J Small Anim Pract 42(11):550-553