Objectives: The objective of this study was to describe the efficacy and safety of low-dose chemotherapy(≤50% of standard dose)for canine osteosarcoma.
Methods: Canine osteosarcoma treated with amputation and low-dose cisplatin or carboplatin(i.e., cisplatin ≤35 mg/m², carboplatin ≤150 mg/m²)as adjuvant chemotherapy was investigated. Dogs with limb amputation and adjuvant chemotherapy(adjuvant chemotherapy group, n=10(cisplatin, n=3; carboplatin, n=7))were compared to dogs receiving no treatment(no-treatment group, n=5)or limb amputation alone(surgery-alone group, n=5)in the same period.
Results: For cisplatin, the median dose was 25 mg/m², median number of treatments was 12, and median interval was 3 weeks. For carboplatin, the median dose was 100 mg/m², median number of doses was 11, and median treatment interval was 3 weeks. Most clinical and hematological abnormalities were mild or moderate. Median survival times for the no-treatment group, surgery-alone group, and adjuvant chemotherapy group were 84 days, 60 days, and 317 days, respectively. The adjuvant chemotherapy group showed significantly increased survival compared to the no-treatment and surgery-alone groups(P<0.05, P=0.023).
Clinical Significance: Low-dose cisplatin or carboplatin chemotherapy may improve outcomes for cases of canine osteosarcoma with limb amputation.

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A 16-year-old intact female mongrel cat was brought to the hospital at night in an emergency with a chief complaint of persistent coughing for half a year and acute deterioration with mouth breathing. Since a chest X-ray showed an intratracheal mass, endoscopic partial resection and intraluminal tracheal stenting were carried out to improve respiration. The tumor stage was diagnosed as T1N0M0, and the postoperative pathological diagnosis was primary intratracheal carcinosarcoma. Emergency respiratory conditions such as open-mouth breathing, cyanosis, exercise intolerance, neck extention position, anorexia, and slavering were improved immediately after endoscopic partial resection and intraluminal tracheal stenting, and the quality of life(QOL)also improved. The patient died of respiratory failure on day 36 by tumor invasion into the stent. This procedure was carried out as palliative therapy, and the owner was satisfied with the outcome because the patient's QOL was improved until death occurred.

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