The purpose of this study was to assess the toxicoses and antitumor activity of metronomic chlorambucil at a dosage of 4 mg m(-2) daily in dogs with naturally occurring cancer. Thirty-six dogs were enrolled in the study. The protocol was well tolerated with no grade 3 or 4 toxicoses noted. Complete remission was achieved, and lasted over 35 weeks in three dogs (mast cell tumour, soft tissue sarcoma and thyroid carcinoma). Partial remission was noted in 1 dog with histiocytic sarcoma (39 weeks duration) for an overall remission rate of 11% (4 of 36). Stable disease was noted in 17 dogs (47%) with various other cancers. The median progression-free interval was 61 days, and the median survival time was 153 days. Chlorambucil given in a metronomic protocol showed antitumor activity in dogs with a variety of naturally occurring cancers.

Background: Cisplatin combined with a nonselective cyclooxygenase (cox) inhibitor has potent antitumor activity against transitional cell carcinoma (TCC) in dogs, but this treatment is limited by renal toxicosis. Cox-2 is expressed in TCC, but only in limited sites within the kidney. A cox-2 inhibitor could enhance the antitumor activity of cisplatin with potentially fewer adverse effects on the kidney.Hypothesis: Cisplatin/cox-2 inhibitor treatment will have greater antitumor activity but no more renal toxicosis than cisplatin alone in dogs with TCC.Animals: Forty-four dogs with naturally occurring urinary bladder TCC. Methods: Dogs were randomized to receive cisplatin (60 mg/m 2 IV q21d), firocoxib (5 mg/kg PO q24h), or the combination. Tumor measurements were determined before and at 6-week intervals during treatment. Renal function was monitored by serum creatinine concentration, iohexol clearance, and urine specific gravity. Toxicoses were graded according to Veterinary Co-Operative Oncology Group (VCOG) criteria.Results: The remission rate with cisplatin/firocoxib (57%) was significantly (P = .021) higher than that with cisplatin alone (13%). Renal and gastrointestinal toxicoses were common in dogs receiving cisplatin, but there were no significant differences between dogs receiving cisplatin or cisplatin/firocoxib. Firocoxib alone induced partial remission or stable disease in 20 and 33% of dogs, respectively.Conclusions: Firocoxib significantly enhanced the antitumor activity of cisplatin resulting in partial remission in more than half of the cases. The toxicoses inherent to cisplatin, however, were noted in dogs receiving this combination. Firocoxib had antitumor effects as a single agent and can be considered a palliative treatment for dogs with TCC.

Because of minimal efficacy and associated renal and gastrointestinal toxicosis, administration of cisplatin (40 to 50 mg/m(2)) with piroxicam cannot be recommended for treatment of dogs with TCC of the urinary bladder.

The purpose of this retrospective study was to determine if 4Gy fractions over 5 consecutive days is an effective and safe palliative radiation protocol for dogs and cats. Eighty patients (22 cats, 58 dogs) with complete follow-up information were evaluated. Overall response rate (ORR) for all patients was 67%. Median progression free survival (MPFS) was 3.3 months and median survival (MST) was 4.2 months. Primary bone tumors were the most common tumors treated. The ORR for primary bone tumors was 66.6%, the MPFS was 3.5 months, and MST was 3 months. The most common tumor treated in cats was oral squamous cell carcinoma and ORR was 54.5 %, the MPFS was 1.8 months, and MST was 3 months. Soft tissue sarcomas were the second most common tumor treated in dogs (10). ORR was 80% and the two other patients had stable disease. MPFS was 5.7 months and MST was 7.9 months. Overall rate of toxicity was 18.4% in 65 sites that were evaluated for toxicity. Acute toxicities were all grade I or II and occurred in 16.9 % of patients evaluated. All late toxicity was grade I alopecia and leukotrichia. There appears to be a comparable response rate for this palliative protocol as compared to others historically. This response was seen over a wide range of tumors. We also documented a low toxicity profile in a shorter overall treatment time, making this protocol more attractive for some clients.

The acute rise in SCR following cisplatin treatment can be worsened by the addition of cox inhibitors, especially those that inhibit cox-1.