New Born Formation? Let's Learn About Canine Hypertrophic Osteopathy
Mon, October 25, 2021

New Born Formation? Let's Learn About Canine Hypertrophic Osteopathy




Hypertrophic osteopathy (HO) occurs when new bone forms on the bones of the limbs, said Top Dog Health, a resource about dog orthopedic disease, surgery, and rehabilitation. Known as periosteal proliferation, new bone initially forms on the bones of the paw, gradually reaching all the way to the limb.

Although the mechanism behind the new formation of bone is unknown, it occurs when nerve signals get disrupted, leading changes in blood supply to the periosteum or the covering of the bones. However, abnormal bone growth can also be a response from a primary, underlying disease, said Tabitha Kucera RVT, CCBC, KPA-CTP, of The Spruce Pets, a pet website. It can vary but the primary disease is often malignant in nature. This causes new bones to form on the surfaces, which is nodular and can affect your dog’s four limbs.


Hypertrophic Osteopathy In 30 Dogs (2013)

M. Salyusarenko and colleagues of the Israel Journal of Veterinary Medicine (IJVM), which was founded in 1922, included 30 dogs (20 females and 45 males) in the HO group. Non-survivors represented those canines that died naturally or were euthanized due to the primary disease within 30 days of diagnosing them with HO (study group) or from their first presentation (controls). Boxers were more overrepresented in the HO group than mixed breed dogs and were overrepresented in the HO group than the general HUVTH (Hebrew University Veterinary Teaching Hospital) dog population (13.3% and 5.5%). 30 days (range 1 to 90 days) was the median duration of HO-related clinical signs like lameness, limb weakness, and swelling prior to the presentation.  

Data about the appearance of clinical signs of HO in correlation with the signs of the primary disease were available in 27 out of 30 dogs. Clinical signs of HO and of the primary disease (i.e., respiratory system-or esophageal mass-related signs) were observed concurrently in 63% of dogs (17 dogs). 22% (six dogs) had  HO-related signs precede the primary disease while 15% (four dogs) had thoracic disease-related signs preceded those of the HO. HO-related clinical signs preceded or occurred concurrently with primary disease signs for 85% of dogs (23 dogs).

Pyrexia was more frequent in the HO group (11 dogs, 50%) compared to the control group (16, 19%). Dogs in the HO group (77%; 23/30 dogs) had swollen limbs or joints at presentation unlike those in the control group (3%; 3/101 dogs ). 27% of dogs in the HO group, but not those in the control group, had warm limbs or pain upon palpation that occurred in conjunction with swelling. Morphological blood smear assessment was available in 11 dogs with HO and 17 controls. Unlike those in the control group, dogs with HO had significantly higher proportions of schistocytosis (6%; 1/17 dogs and 55%; 6/11 dogs) and anisocytosis (65%; 11/17 dogs and 91%; 10/11 dogs).



Caudal mediastinum was the most common thoracic lesion location among canines in the HO group (37%; 11/30). 27% of dogs (eight dogs) had multiple lesions or metastases. 29/30 limb radiographs of the HO dogs were available and re-examined when the research was done. The locations of the periosteal reaction typical of HO consisted of metacarpi or metatarsi (76%; 22/29 dogs), distal long bones (66%; 19/29 dogs), proximal long bones (38%; 11/29), carpi or tarsi (31%; 9/29), phalanges (21%; 6/29), and pelvis, ribs and scapula (3%; one each). HO-associated pathologies comprised of esophageal mass (33%; 10/30), MLD (metastatic lung disease) (27%; 8/30), primary pulmonary mass (20%; 6/30), intrathoracic-extrapulmonary (thoracic wall) mass (13%; 4/30).


Why Does Hypertrophic Osteopathy Occur?

Symptoms occur gradually or acutely depending on the primary disease’s severity. While the primary disease can vary, dogs typically have a cancerous tumor of the chest and the abdomen. Certain bacterial or viral infections, bone cancers, or other masses that affect your dog’s internal organs can trigger new bone growth.  Rib tumors, lung tumors, lung abscess, infection of the heart valve or infective endocarditis, etc. can also cause hypertrophic osteopathy. The most common underlying cause of this condition is metastatic pulmonary lesions.  Large breeds, especially Boxers, over eight and a half years old are more likely to have hypertrophic osteopathy.



What Are The Signs of Hypertrophic Osteopathy and How Is It Diagnosed?

Consult your veterinarian if you notice limb swelling in your dog, as it is one of the symptoms of hypertrophic osteopathy. Other symptoms include coughing, blood in urine, weight loss, lameness, lethargy or reluctance to move, decreased appetite. During the diagnosis, your veterinarian will get to know your dog’s medical history, including the onset of symptoms, its activity level, travel history, and if it takes any supplements or medications

A thorough physical examination will be conducted, which can be painful for your dog. Your veterinarian will carefully palpate or put pressure on all swollen limbs. This way, they will be able to identify the steps your veterinarian will take for creating an optimal treatment plan and to gauge your dog’s level of pain. X-rays of the limbs will also be done to evaluate the affected bones and to check for any signs of cancer and masses. Your veterinarian may recommend an ultrasound to evaluate your pet’s organ structure.  An ultrasound can be more accurate and sensitive when viewing a particular organ and details of a soft tissue. Your veterinarian may need to gather more samples for specialized testing evaluation at a larger laboratory depending on your dog’s initial lab work and diagnostic results.



How Is Hypertrophic Osteopathy Treated?

The results from the physical exam, x-rays, medical history, and lab work will enable your veterinarian to formulate the most appropriate diagnosis and treatment plan for your dog. Successful treatment of the primary disease is essential in addressing hypertrophic osteopathy. Treatment can include removing a mass through surgery where there is no sign of cancer spreading and treating an underlying diagnosed bacterial or fungal infection.

Wellness care involves visiting your veterinarian at least once a year even if your dog does not need to be revaccinated. During vet exams, provide a detailed history of your dog and let your veterinarian know of any changes to its personality and behavior, as well as eating, drinking, and bathroom habits. Inform them of any medications and supplements, including alternative treatments your dog took prior to the appointment. If you have a senior dog, have it undergo x-rays so that your veterinarian can determine any changes in its internal organs and bones. This will help them evaluate if your dog’s organs appear normal or need to be addressed immediately.


Hypertrophic osteopathy can be painful for dogs, especially when its swollen limb is examined. The veterinarian will identify the primary disease to help address hypertrophic osteopathy. Owners should be cognizant of any changes in their dog’s behavior for early diagnosis and treatment.