SHARED on 04 Jun, 2019
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Osteosarcoma

It has been estimated that Osteosarcomas represent as much as 80% of all dog bone cancers.

Overview

Osteosarcoma is one of the most common bone cancers in dogs representing over 80% of all bone cancers in dogs. Bone cancer is predominantly a cancer of older dogs but can also occur in dogs 1-2 years of age. Males appear to be affected more commonly than females. It has been estimated that dogs weighing >30kgs are at least 60 times more likely to develop this cancer than dogs weighing less than 30kgs.

Osteosarcomas seem to arise with no known cause. They are highly aggressive and can spread to other organs such as the lungs. The metastatic rate of this cancer is 90%.

Dog breeds commonly affected by bone cancer:

  • Rottweiler
  • Saint Bernard
  • Newfoundland
  • Bernese Mountain Dog
  • Great Dane
  • Golden Retriever
  • Dobermann
  • Weimaraner
  • Boxer

Signs

Commonly signs of bone cancer:

  • Lameness
  • Solid bone swelling
  • Weight loss
  • Exercise intolerance
  • Loss of appetite
  • Aggression

Commonly affected areas:

  • Shoulder
  • Wrist
  • Knee
  • Arm
  • Leg

Causes

Osteosarcomas tend to arise spontaneously. Currently, there are no apparent causes.

Diagnosis

Your veterinarian may perform a full physical examination, run blood tests, and or/radiographs of the affected bone and chest.

Unfortunately, 95% of dogs will have metastases to the lungs.

Management

The goals of treatment are to offer pain control and improve the quality of life. This may include surgery to remove a tumor such as a limb amputation as well as therapies to reduce the risk of spreading.

Treatment options that your veterinarian could discuss with you:

  • No treatment
  • Chemotherapy e.g. carboplatin or doxorubicin-based
  • Radiation therapy
  • Pain management
  • Amputation of the affected limb
  • Surgery to remove the affected bone

Prognosis

Osteosarcomas that occur in a leg bone often spread to other organs. Osteosarcomas that occur in the spine, pelvis, or ribs are often difficult to surgically remove. Survival is dependent on cancer location and treatment.

A poor prognosis is given to younger animals, large tumor sizes, high histopathological grades, humerus location, and elevated ALP blood levels.

Unfortunately, the cure for osteosarcomas occurs in less than 25% of cases.

Average mean survival times

No treatment with medical management alone 4-6 months
Amputation only 4-6 months
Amputation with chemotherapy 12-18 months
Radiation therapy 6-8 months
Bisphosphonate therapy 6-9 months

Factors that worsen the prognosis

Studies show that dogs with a high serum ALP at the time of diagnosis had a shorter survival rate of around 5.5 months compared to dogs with a normal serum ALP.

Dogs between the age of 7-10 years had the longest survival times - dogs outside this age range had lower survival rates.

Homecare

Tips for caring for a dog being treated for osteosarcoma:

  • Encourage dogs to walk unassisted 24 hours following limb amputation
  • Check any surgery wounds twice a day for bleeding, discharge, or broken sutures
  • Bandage changes every 3 days
  • Restrict exercise for the first 4 weeks to leash walking only

References

Ru G, et al: Host-reduced risk factors for canine osteosarcoma. Vet.J. 1998;156:31-39.

Li XQ, et al: Relationship between metallic implants and cancer: A case-control study in a canine population. Vet.Comp.Orthopaedics and Traumatology 1993; 2:70-74.

Kuntz CA, et al: Limb salvage surgery for osteosarcoma of the proximal humerus: outcome in 17 dogs. Vet.Surg. 1998; 27:417-422.

Degna MT, et al: Bone transport osteogenesis for limb salvage. Vet.Comp.Orthopaedics and Traumatology 2000; 13:18-22.

McEntee MC, et al: Palliative radiotherapy for canine appendicular osteosarcoma. Vet.Radiol.Ultrasound 1993; 34:367-370.

Berg J, et al: Effect of timing of postoperative chemotherapy on survival of dogs with osteosarcoma. Cancer 1997; 79:1343-1350.

Bergman PJ, et al: Amputation and carboplatin for treatment of dogs with osteosarcoma: 48 cases (1991to 1993). J.Vet. Intern. Med. 1996; 10:76-81.

Ehrhart N, et al: Prognostic importance of alkaline phosphatase activity in serum from dogs with appendicular osteosarcoma: 75 cases (1990-1996). J.Am.Vet Med.Assoc. 1998; 213:1002-1006.

Garzotto CK et al. Prognostic significance of serum alkaline phosphatase activity in canine appendicular osteosarcoma. J.Vet. Intern. Med. 2000; 14:587-592.

Kirpensteijn J et al. Prognostic significance of a new histologic grading system for canine osteosarcoma. Vet Pathol. 2002; 39:240-246.