(Also previously called achropachia, hypertrophic osteoarthropathy (HOA), hypertrophic pulmonary osteoarthropathy (HPOA), hypertrophic pulmonary osteopathy (HPO), Marie's disease, osteoporosis deformans, pulmonary osteoarthropathy (POA) ) 

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Topics on this Page:

Hypertrophic osteopathy (HO) is a severely debilitating disease which occurs secondary to other diseases. The primary disease is usually a cancer, but occasionally others e.g. infectious diseases such as tuberculosis, and most often they involve the lungs or are disease processes lying within the chest. Affected animals develop bilateral, symmetrical soft tissue swelling of the lower legs with periosteal new bone formation. These bony changes do not involve the joints or joint capsule.

The precise cause of hypertrophic osteopathy is not yet understood. Blood flow to the lower limb is greatly increased in the early stages of the disease.

Secondary lung cancer is the disease most often associated with HO, and primary lung cancer and primary bone cancer with secondary spread to the lungs are also very commonly reported. Dogs that have had amputation for bone cancer have a predisposition to develop hypertrophic osteopathy.

In the United States of America (Eastern States mainly) animals infected with spirocercosis, and in other parts of the world as well as the USA animals infected with heartworm may develop hypertrophic osteopathy.

Breed Occurence
Any breed of dog can be affected as can cats, sheep, cattle, horses, birds and other species.

Large breeds of dog are most often presented to veterinarians with the disease. The Boxer is particularly over-represented in case reports - but this probably reflects the high occurrence of bone cancer and primary lung cancer in this breed. The German Shepherd dog is also reported frequently.

Except for large and giant breeds of dog which can develop bone cancer at an early age, the age of onset is usually middle-aged to older animals, reflecting the increasing incidence of cancers with advancing age.

Females more often affected than males - possibly related to the common occurrence of mammary carcinomas.

Usually animals are presented because they are lame and reluctant to move around. They have symmetrical firm soft tissue swellings of the lower legs. The limbs are warm to touch and often very painful when pressed.

The diagnosis is confirmed by Xrays . In the early stages soft tissue swelling is seen, but this is followed by perisosteal new bone development which can appear to be smooth, or irregular. Most often the metacarpal or metatarsal bones are affected.

Radiographs of the chest will frequently identify the underlying disease process. If the primary disease process can be successfully treated (e.g. the excision of a space occupying lesion in the chest such as an abscess) the bony changes regress.

Differential diagnosis:

  1. In dogs HO needs to be differentiated from osteomyelitis, bone tumours, hypertrophic osteodystrophy in young dogs, panosteitis, osteoarthritis (in the early stages) and the soft tissue swelling from oedema.
  2. In cats : hypervitaminosis A and mucopolysaccharidosis

Successful treatment depends upon the underlying cause. Secondary lung cancer brings with it a very poor prognosis and euthanasia usually results. However, some causes such as heartworm infestation (not in the UK yet) and primary lung tumours can be treated by surgical removal of the underlying cause, with good results.

Otherwise treatment is palliative relying on the use of analgesics to relieve pain.


Updated October 2013