fibrodysplasia

Fibrodysplasia ossificans

This is a rare genetic disorder which typically affects young adult middle aged dogs of both sexes. Rapid increase of fibrovascular tissue within the muscle occurs, with secondary calcification and ossification (chronic, painful wounds and calcified deposits in the paws and abdomen). It is not known if this disease represents a primary muscle disorder or if this is an abnormality of connective tissue adjacent to muscle (e.g. tendons,) that leads to a secondary myopathy.

calcification
Impregnation with calcium or calcium salts leading to hardening of tissue with such impregnation

ossification
The abnormal hardening or calcification of soft tissue into a bone-like material

fibrovascular
Having fibrous tissue and vascular tissue

Clinical signs include progressive weakness and stiffness of gait, enlargement of proximal limb muscle, muscle pain and visible limb swelling, marked wasting of the muscles, and limited mobility of all joints.

Diagnosis is based primarily upon signalment, clinical signs and x-ray evidence of mineralized/ossified densities (usually multiple) within muscle tissue. Creatine kinase levels are typically elevated and EMG evaluation reveals abnormal potentials. Histopathologically, fibrosis, myofiber necrosis and phagocytosis, and areas of calcification/ossification may be seen.

Fibrodysplasia ossificans progressiva is associated with the dysregulated production of bone morphogenetic protein 4 (BMP4), a potent osteogenic morphogen. BMPs play an important role in the growth and development of numerous tissues, including bone, brain, and spinal cord.
The prediction of the probable course and outcome of this disease is considered guarded to poor as it is a progressive disease. The focal lesions may regress or respond well to surgical excision Inheritance of the disorder has not yet been demonstrated.

source
A practical guide to canine and feline neurology-Curtis W Dewey, Anton G Hoffman

Fibrodysplasia ossificans in a German shepherd dog.

Bone morphogenetic protein
signal transduction in bone

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.