Background: Histiocytic sarcoma is an aggressive neoplasm of dendritic cells that carries a grave prognosis. The efficacy of chemotherapy against this disease is unknown. The purpose of this study was to determine the efficacy of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) in dogs with incompletely resected or metastatic histiocytic sarcoma, to describe the clinical characteristics of these dogs, and to identify factors affecting prognosis.Hypothesis: Our hypothesis is that CCNU has activity against canine histiocytic sarcoma and can improve survival in dogs with advanced disease.Animals: Included in analysis are dogs diagnosed with histiocytic sarcoma who had gross measurable or residual microscopic disease and who received CCNU.Methods: A multi-institutional, retrospective, single-arm cohort study was conducted. Available biopsy samples were tested with an antibody against CD18 when possible to confirm the diagnosis of histiocytic sarcoma.Results: Fifty-nine dogs were treated at 8 institutions. Twenty-three tumor specimens were confirmed to be CD18 positive. Treatment with CCNU at 60 to 90 mg/m 2 resulted in an overall response rate of 46% in the 56 dogs with gross measurable disease. All 3 dogs with minimal residual disease experienced tumor relapse but lived 433 days or more after starting CCNU. The median survival of all 59 dogs was 106 days. Thrombocytopenia (,100,000 platelets/mL) and hypoalbuminemia were found to be negatively associated with prognosis and were predictive of ,1 month survival.Conclusions and Clinical Importance: Results suggest that CCNU is active against canine histiocytic sarcoma and may be useful in the treatment of dogs without negative prognostic factors.

Background: Some retired racing Greyhounds (RRG) that undergo surgery bleed excessively. Hypothesis: Greyhounds that bleed excessively will have one or more preoperative hemostatic abnormalities that can be used to predict the risk and severity of postoperative bleeding.Animals: Eighty-eight RRG undergoing ovariohysterectomy or castration. Methods: All dogs were evaluated preoperatively with a physical exam, CBC, platelet count, OSPT, APTT, platelet function with PFA-100 a ; fibrinogen, D-dimer, plasminogen (Plmg), antiplasmin (AP), antithrombin (AT), and vWF concentration (vWF:Ag); vWF collagen binding assay (vWF:CBA), and Factor XIII assay. Assays were repeated in the dogs that bled, and in an age-and sex-matched control group of RRG.Results: Twenty-six percent of the dogs had bleeding 36-48 hours after surgery. AP (P o.0001) and AT concentration (P 5 .007) were significantly lower, and vWF:CBA (P 5 .0284) was higher preoperatively in the dogs with excessive hemorrhage. A lower platelet count (P 5 .001) and hematocrit (P 5 .002), shorter OSPT (P 5 .0002) and higher plasma fibrinogen (P o.0001), and AP (P 5 .001) concentration were detected at the time of bleeding compared with preoperative values in the dogs that bleed excessively. The same findings were observed postoperatively for the control group, except for the decrease in hematocrit.Conclusions and Clinical Importance: The results indicate that this excessive postoperative bleeding is not attributable to a primary or secondary hemostatic defect, but could result from altered fibrinolysis.

Use of a long-term doxorubicin-containing sequential combination chemotherapy protocol is associated with a decreased risk of relapse and death relative to a non-doxorubicin-containing protocol.

Canine lymphoma is a heterogeneous group of diseases and many previous studies have evaluated the response of a mixed population of lymphoma cases to one specific treatment protocol. The aim of this retrospective study was to describe the outcome and prognostic factors in 42 cases of multicentric centroblastic diffuse large B-cell lymphoma treated with either a COP-type (35%) or CHOP-type (64%) induction chemotherapy. The objective response rate to induction therapy was 94%; entire dogs had a greater rate of complete vs partial remissions than neutered dogs (P = .017). Median progression-free survival for the first remission (PFS1) was 182 days; absence of anaemia at diagnosis (P = .002) and pretreatment neutrophil:lymphocyte ratio (NLR) below 9.44 (P = .015) were independently predictive of longer PFS1. Fifty-eight percent of dogs received rescue protocols with an objective response rate of 81%; 31% of dogs received further rescue protocols (up to a total of 5) and the median number of protocols administered were 2. Median overall survival (OS) was 322 days, the 1-year survival rate was 38% and the 2-year survival rate was 9%. Lymphocyte:monocyte ratio above 1.43 (P = .031), NLR below 11.44 (P = .009), the combination of induction and rescue therapy (P = .030) and the total number of doxorubicin doses used (P = .002) were independently predictive of longer OS. Use of a COP-type protocol induction compared with CHOP did not undermine OS providing doxorubicin was used as rescue therapy.