Disorder - Fibrodysplasia ossificans

Organ Systems Involved
Musculoskeletal

Alternative Names
Fibrodysplasia ossificans progressiva (FOP); Myositis ossificans progressiva

Presenting Signs

Fibrodysplasia ossificans progressiva is a rare disorder, with only six cases as yet reported. In this disorder, bone progressively forms on other tissues such as muscles, tendons, ligaments, connective tissues and across joints. The most remarkable clinical sign is the sudden enlargement of muscles with no history of trauma. The gait becomes progressively stiff and the range of movement is decreased. Affected cats also have a fever (up to 40° C). X-rays show multiple areas of mineralisation, or bone deposit, on several muscles within the affected leg/s. Any area of the body may be affected but it typically occurs in the limbs, jaw, shoulder and groin area. The condition progresses rapidly, and animals become severely to completely immobile within two weeks to several months.

Cats at Risk

No breed is preferentially affected; clinical signs generally appear in young adult to middle-age cats (before ten years of age), and both sexes are affected. In humans, FO is an inherited disorder, but at present the degree of heritability in cats is unknown.

Treatment

There is no effective surgical or medical protocol available for this disorder at present.

PubMed References
Fibrodysplasia ossificans

Contributor
Candy Wong