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HO - Issue Description

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Issue Name


Other Names
Hypertrophic Osteopathy

Issue Description

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.


  • Listlessness
  • Reluctance to move.
  • Lameness in one or more legs.
  • Sore legs.
  • Legs that are enlarged and firm to the touch.
  • Swelling of the toes extending to the level of the elbow and stifle joints

  • Diagnosis

    Your veterinarian may suspect HO after examining your pet, but will probably perform several tests to confirm the diagnosis and to identify the underlying cause. HO is an indicator of another disease process; therefore, it is important to understand the need for further diagnostic tests to identify the primary cause. Radiographs (X-rays) of the affected bones generally show characteristic changes for this condition. Radiographs of the chest and abdomen, and an ultrasound study of the abdomen are often performed to look for the underlying cause of the HO condition. Blood tests are performed to assess the general health of your pet and to look for organ dysfunction that may point to an underlying cause.


    Although it has been theorized that HO may be caused by toxins, nerve signal malfunctioning, or poorly oxygenated blood reaching your dog's skeletal structure, it is not definitively known what causes HO.

    All dog breeds can suffer from HO, but it is more common in large breeds. Based on case reports, the Boxer dog have a higher risk of developing HO compared to other breeds. This is probably caused by the higher occurrence of primary lung cancer and bone cancer in this breed. The German Shepherd also has an elevated risk of developing HO.

    HO is more common in female dogs than in male dogs. This is probably related to the fact that mammary carcinomas can lead to HO.

    When small and medium sized dogs get HO, they are usually middle aged or older, since cancers are less common in young dogs. Large and giant dog breeds are however prone to developing bone cancers while still fairly young and vets are therefore quite frequently presented with young, large dogs with HO.


    The treatment for HO is to identify, and in most instances surgically remove the underlying mass (tumor). The type and extent of surgery required depends on the underlying cause.


    Removal of the inciting cause may or may not bring about regression of clinical signs. Lameness and limb disfigurement due to bony changes may take several months to regress, if at all. The prognosis for animals with HO is generally guarded to poor due to the frequent recurrence of the tumors.

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