CVC Highlight: Alleviating cancer pain: A case study
Editors' Note: This case was presented in a session entitled "Case studies in cancer pain management" during the International Veterinary Academy of Pain Management (IVAPM) symposium at CVC Kansas City, Aug. 30, 2009.
Because the tumor clearly extended in the extraosseous subcutaneous tissues of the antebrachium, an ulnectomy could not be recommended since complete surgical margins could not be obtained. Thus, the therapeutic options discussed included standard therapy combining amputation of the left forelimb and adjuvant chemotherapy as well as palliative options such as hypofractionated radiation therapy, intravenous aminobisphosphonate administration (pamidronate or zoledronate), and oral analgesic therapy.
The owners declined amputation and any injectable therapy. Because of the elevated ALT activity, they were instructed to discontinue carprofen administration, but they initially refused adjuvant analgesic therapy. Three weeks later, with the ALT activity back in the normal range, deracoxib was prescribed (1.2 mg/kg orally once a day). A good clinical response was observed with complete resolution of the lameness.
We opted to continue therapy with deracoxib because it was well-tolerated and provided adequate analgesia in monotherapy for more than a year and because the recurring pain and lameness were thought to be due to an increased level of pain rather than decreased analgesic efficacy of the drug itself. Tramadol hydrochloride was prescribed at a dosage of 4 mg/kg orally twice a day, as well as amantadine at a dosage of 5 mg/kg orally once a day.
Tatou had an excellent quality of life for two additional months, but presented one day following an acute episode of nonweight-bearing lameness. A radiograph of the left forelimb confirmed a pathologic fracture of the ulna and the radius (Figure 6). The owners then opted for euthanasia, 445 days after diagnosis.
This case demonstrates that, though unusual, certain cases of cancer may respond well to conservative analgesic therapy initially but eventually require multimodal analgesia for proper control once pain progresses and becomes more severe. It also demonstrates that despite a poor prognosis once advanced metastasis is detected, palliative therapy to improve comfort should be considered and may result in added months of excellent quality of life.
Louis-Philippe de Lorimier, DVM, DACVIM (oncology)