Current treatment options for dogs with appendicular osteosarcoma - Veterinary Medicine
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Current treatment options for dogs with appendicular osteosarcoma
Your therapeutic choices for dogs with osteosarcoma in their limbs continue to expand. Deciding which option is best comes down to the site and extent of the tumor and the owner's preference.


VETERINARY MEDICINE


MEDICAL MANAGEMENT

Many owners of affected dogs do not perceive the outcome of surgery (with or without chemotherapy) to be worthwhile. In these instances, medical management of the primary tumor may be elected. Medical management typically consists of daily treatment with a nonsteroidal anti-inflammatory drug (NSAID) to alleviate the associated bone pain. When lameness worsens and is refractory to treatment with NSAIDs, oral formulations of various opioids may provide more effective pain control.

In human medicine, osteolytic bone diseases (e.g. bone metastases and hypercalcemia of malignancy) are often treated with a class of drugs called bisphosphonates.64 Bisphosphonates reduce bone resorption by inhibiting osteoclast function.64 There is only one clinical report of the use of bisphosphonates in dogs with spontaneously occurring osteosarcomas.65 In this report, alendronate was used as palliative treatment in two cases of primary canine osteosarcoma, one affecting the tibia and the other affecting the maxilla. According to the report, both dogs remained comfortable, surviving for 12 and 10 months, respectively. However, since only two dogs were studied, there was no control group, and survival was the only parameter measured, it is difficult to conclude what benefit alendronate provided. This case report, along with evidence for efficacy in the treatment of various malignant bone diseases in people, has prompted veterinary clinicians to treat some cases of primary canine osteosarcoma with bisphosphonates. Recently, the bisphosphonates alendronate, pamidronate, and zoledronate have been shown to inhibit canine osteosarcoma cell growth in vitro, raising the possibility that bisphosphonates may also be helpful as adjunctive chemotherapeutic agents.66-68

CONCLUSION

Amputation in conjunction with chemotherapy continues to be the most common and effective treatment available for dogs with appendicular osteosarcoma5,41; however, new approaches are being developed that should prolong survival times and decrease morbidity. As the efficacy of treatments such as limb-salvage surgeries, radiation, and chemotherapy are established, practitioner and owner interest will grow.

Editors' Note: One of the authors, Dr. Charles A. Kuntz, developed the endoprosthesis method discussed above and receives compensation for every unit sold from Veterinary Orthopedic Implants, which manufactures the endoprostheses.

Carl T. Jehn, DVM
James P. Farese, DVM, DACVS
Daniel D. Lewis, DVM, DACVS
Department of Small Animal Clinical Sciences and the Center for Veterinary Sports Medicine
College of Veterinary Medicine
University of Florida
Gainesville, FL 32610-0126.

Nicole Ehrhart, VMD, MS, DACVS
The Animal Cancer Center
College of Veterinary Medicine
Colorado State University
Fort Collins, CO 80523.

Charles A. Kuntz, DVM, MS, DACVS
Regional Veterinary Referral Center
6651-F Backlick Road
Springfield, VA 22150

REFERENCES

1. Withrow SJ, MacEwen EG. Tumors of the skeletal system. In: Clinical veterinary oncology. Philadelphia, Pa: JB Lipincott Co, 1989;378-392.

2. Priester WA. The occurrence of tumors in domestic animals. In: National Cancer Institute, monograph no. 54. NIH publication no. 80-2046. New York: Oxford University Press, 1982.

3. Tjalma RA. Canine bone sarcoma: Estimation of relative risk as a function of body size. J Natl Cancer Inst 1966;36:1137-1150.

4. Brodey RS, Riser WH. Canine osteosarcoma: A clinicopathologic study of 194 cases. Clin. Orthop. 1969;62:54-64.

5. Brodey RS, Abt DA. Results of surgical treatment in 65 dogs with osteosarcoma. J Am Vet Med Assoc 1976;168:1032-1035.

6. Ling GV, Morgan JP, Pool RR. Primary bone tumors in the dog: A combined clinical, radiographic, and histologic approach to early diagnosis. J Am Vet Med Assoc 1974;165:55-67.

7. Phillips L, Hager D, Parker R, et al. Osteosarcoma with a pathologic fracture in a six-month-old dog. Vet Radiol 1986;27:18-19.

8. Spodnick GJ, Berg J, Rand WM, et al. Prognosis for dogs with appendicular osteosarcoma treated by amputation alone: 162 cases (1978-1988). J Am Vet Med Assoc 1992;200:995-999.

9. McGavin MD, Carlton WW, Zachary JF. Diseases of bone. In: Thomson's special veterinary pathology. St. Louis, Mo: Mosby Inc 2001;523-524.


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