C. Guillermo Couto

CCNU for the Treatment of Dogs with Histiocytic Sarcoma

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/m2 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/microL) 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.

Cisplatin and Doxorubicin Combination Chemotherapy for the Treatment of Canine Osteosarcoma: A Pilot Study

Sixteen dogs with histologically confirmed appendicular osteosarcoma were treated by amputation followed by cisplatin and doxorubicin chemotherapy. All dogs began chemotherapy within 24 hours of surgery. Cisplatin was administered at 50 mg/m2 intravenously (IV) concurrent with saline-induced diuresis. Doxorubicin was administered 24 hours later at 15 mg/m2 as a slow IV bolus. This protocol was given on a 21-day cycle for 4 cycles. No dose delays were required, but dose reduction of doxorubicin was required in 2 dogs because of neutropenia. Thoracic radiography was performed every 2 months after completion of therapy to monitor for metastatic disease. Two dogs were still alive and free from disease at the time of last contact (24 and 75 months, respectively). Postmortem examinations were performed on 13 of the 14 dogs that died. Eight of these dogs were euthanized because of metastatic osteosarcoma. Of the remaining 5 dogs, euthanasia was performed because of complications of idiopathic megaesophagus (n = 1), arthritis (n = 2), and hemangiosarcoma (n = 2). The median disease-free interval and survival times were 15.7 and 18 months, respectively. When compared to a historical group of 36 dogs with appendicular osteosarcoma treated with surgery and 4 doses of cisplatin. both disease-free interval and overall survival were significantly longer in the study population (P < .015 and P < .007, respectively).

Characterization of canine osteosarcoma by array comparative genomic hybridization and RT-qPCR: Signatures of genomic imbalance in canine osteosarcoma parallel the human counterpart

Osteosarcoma (OS) is the most commonly diagnosed malignant bone tumor in humans and dogs, characterized in both species by extremely complex karyotypes exhibiting high frequencies of genomic imbalance. Evaluation of genomic signatures in human OS using array comparative genomic hybridization (aCGH) has assisted in uncovering genetic mechanisms that result in disease phenotype. Previous low‐resolution (10–20 Mb) aCGH analysis of canine OS identified a wide range of recurrent DNA copy number aberrations, indicating extensive genomic instability. In this study, we profiled 123 canine OS tumors by 1 Mb‐resolution aCGH to generate a dataset for direct comparison with current data for human OS, concluding that several high frequency aberrations in canine and human OS are orthologous. To ensure complete coverage of gene annotation, we identified the human refseq genes that map to these orthologous aberrant dog regions and found several candidate genes warranting evaluation for OS involvement. Specifically, subsequenct FISH and qRT‐PCR analysis of RUNX2, TUSC3, and PTEN indicated that expression levels correlated with genomic copy number status, showcasing RUNX2 as an OS associated gene and TUSC3 as a possible tumor suppressor candidate. Together these data demonstrate the ability of genomic comparative oncology to identify genetic abberations which may be important for OS progression. Large scale screening of genomic imbalance in canine OS further validates the use of the dog as a suitable model for human cancers, supporting the idea that dysregulation discovered in canine cancers will provide an avenue for complementary study in human counterparts.

Seroprevalence of Ehrlichia canis, Ehrlichia chaffeensis and Ehrlichia ewingii in dogs in North America

BackgroundThis study evaluated the exposure of dogs to three different Ehrlichia spp. in the south and central regions of the United States where vector-borne disease prevalence has been previously difficult to ascertain, particularly beyond the metropolitan areas.MethodsDog blood samples (n = 8,662) were submitted from 14 veterinary colleges, 6 private veterinary practices and 4 diagnostic laboratories across this region. Samples were tested for E. canis, E. chaffeensis and E. ewingii specific antibodies using peptide microtiter ELISAs.ResultsOverall, E. canis, E. chaffeensis and E. ewingii seroprevalence was 0.8%, 2.8%, and 5.1%, respectively. The highest E. canis seroprevalence (2.3%) was found in a region encompassing Arkansas, Louisiana, Oklahoma, Tennessee and Texas. E. chaffeensis seroreactivity was 6.6% in the central region (Arkansas, Kansas, Missouri, and Oklahoma) and 4.6% in the southeast region (Georgia, Maryland, North Carolina, South Carolina, Tennessee and Virginia). Seroreactivity to E. ewingii was also highest in the central region (14.6%) followed by the southeast region (5.9%). The geospatial pattern derived from E. chaffeensis and E. ewingii seropositive samples was similar to previous reports based on E. chaffeensis seroreactivity in white-tailed deer and the distribution of human monocytic ehrlichiosis (HME) cases reported by the CDC.ConclusionsThe results of this study provide the first large scale regional documentation of exposure to E. canis, E. chaffeensis and E. ewingii in pet dogs, highlighting regional differences in seroprevalence and providing the basis for heightened awareness of these emerging vector-borne pathogens by veterinarians and public health agencies.

Coagulation Abnormalities Associated with Neoplasia

Subclinical abnormalities in hemostasis occur commonly in small animal patients with cancer, but the incidence of clinical thrombosis or hemorrhage is unknown. Malignancy can lead to abnormalities in both primary and secondary hemostasis, which in turn can lead to either thrombotic or hemorrhagic tendencies. These coagulation abnormalities can be associated with the tumor itself, with anticancer chemotherapy, or with secondary organ dysfunction. Thrombocytopenia and DIC are probably the most common defects associated with clinical bleeding in small animal patients.

Epsilon aminocaproic acid for the prevention of delayed postoperative bleeding in retired racing greyhounds undergoing gonadectomy.

OBJECTIVE To evaluate the effects of epsilon aminocaproic acid (EACA) on the prevalence of postoperative bleeding in retired racing Greyhounds (RRG), and to assess its effects on selected thrombelastography (TEG) and fibrinolysis variables. STUDY DESIGN Double-blinded, prospective, randomized study. METHODS 100 RRG had elective ovariohysterectomy or orchiectomy and were administered EACA or placebo for 3 days after surgery. TEG variables were analyzed preoperatively and 24, 48, and 72 hours after surgery. RESULTS Thirty percent (15/50) of RRG in the placebo group had delayed postoperative bleeding starting 36-48 hours after surgery compared with 10% (5/50) in the EACA group (P = .012). On the TEG variables, the slopes for R and K time were significantly different between treatment groups (P <.05); the R and K time decreased over time in the EACA group after surgery whereas they increased in the placebo group. The angle, maximal amplitude (MA), and G slopes were also significantly different between treatment groups (P = .001, .001, and .006, respectively). The angle, MA, and G increased postoperatively over time in the EACA group and decreased in the placebo group. All these changes are supportive of hypercoagulability associated with EACA administration. CONCLUSION Postoperative administration of EACA significantly decreased the prevalence of postoperative bleeding in RRG undergoing surgery by increasing the clot strength.

Thromboelastography in healthy horses and horses with inflammatory gastrointestinal disorders and suspected coagulopathies

OBJECTIVES To evaluate the use of citrated recalcified (nonactivated) thromboelastography (TEG) in healthy horses and horses with colitis and suspected coagulopathies. DESIGN Prospective, observational study conducted between October 2007 and June 2009. SETTING Veterinary Teaching Hospital. ANIMALS Forty-five healthy adult horses and 12 sick adult horses with colitis and prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Whole blood was collected on admission. Coagulation profile (PT, aPTT, platelet count, and fibrinogen concentration) and citrated recalcified whole blood TEG analysis (R-time [R], K-time [K], angle [α], maximum amplitude [MA], G value [G], lysis at 60 min [LY60]) were evaluated. Mean values (SD) for TEG parameters in healthy horses were: R=10.4 (3.1) minutes; K=3.5 (1.2) minutes; α=46.3 (11.0)°; MA=55.6 (5.1) mm; G=6,429 (1,341) dyn/cm², and LY60=5.1 (2.4)%. Mean coefficients of variation for intra-assay/interindividual variability in healthy horses were: R=4.7%/30.7%, K=4.8%/35.3%, α=4.4%/23.8%, MA=1.4%/9.3%, G=3.4%/20.8%, and LY60=13.1%/47.7%, respectively. Horses with colitis and prolonged PT and/or aPTT had longer mean values for R (P<0.001) and K (P<0.001), narrower mean α (P<0.001), decreased mean MA (P=0.001), and smaller mean G (P=0.02); changes consistent with hypocoagulability. CONCLUSIONS Citrated recalcified (nonactivated) TEG demonstrated changes consistent with hypocoagulability in horses with colitis that had preidentified coagulation abnormalities. This technique has high interindividual variability and low intra-assay variability. TEG may be useful for detecting hypocoagulable states in horses with colitis and suspected coagulopathies.

Serological study of selected vector-borne diseases in shelter dogs in central Spain using point-of-care assays.

We evaluated the prevalence of selected vector-borne diseases in 131 dogs in an animal shelter in central Spain using point-of-care assays (SNAP 4DX and SNAP Leishmania; IDEXX Laboratories, Westbrook, ME). The SNAP 4DX detects Dirofilaria immitis (Di) antigen and antibodies against Ehrlichia canis (Ec), Borrelia burgdorferi (Bb), and Anaplasma phagocytophylum (Aph); the SNAP Leishmania kit detects antibodies against Leishmania infantum (Li). Dogs were classified as healthy or sick based on physical examination, complete blood counts, and serum chemistry profiles. The prevalence of positive test results was as follows: Ec, 5.3% (n = 7); Aph, 19.0% (n = 25); Bb, 0%; Di, 0%; and Li, 5.3% (n = 7). Four dogs (3%) were coexposed to Ec and Aph, and three dogs (2.3%) were coexposed to Aph and Li. There was no statistically significant correlation between positive serology and clinical status (sick vs. healthy) or hematologic/biochemical abnormalities. The prevalence of Aph was the highest and is in agreement with a recent report in a dog shelter in northwestern Spain. These point-of-care assays may be more valuable as epidemiologic than as clinical tools.

Effects of hematocrit and red blood cell-independent viscosity on canine thromboelastographic tracings

It is well established that hematocrit (Hct) influences whole blood thromboelastography (TEG) tracings. Previous studies showed hypercoagulable TEG tracings in anemic patients despite clinical expectations that anemia often prolongs bleeding. TEG is a viscoelastic assessment of clot kinetics, and Hct is the main determinant of whole blood viscosity. TEG changes in anemia may be an in vitro artifact due to Hct effect on blood viscosity rather than true in vivo changes in hemostasis. The effect of changes in whole blood viscosity on TEG independent of Hct is not well understood.

Retrospective evaluation of the effectiveness of epsilon aminocaproic acid for the prevention of postamputation bleeding in retired racing Greyhounds with appendicular bone tumors: 46 cases (2003–2008)

OBJECTIVES To determine the frequency of delayed postoperative bleeding in retired racing Greyhounds with appendicular bone tumors undergoing limb amputations. To identify if administration of epsilon-aminocaproic acid (EACA) was effective on the prevention of postoperative bleeding. DESIGN Retrospective study from December 2003 to December 2008. SETTING Veterinary university teaching hospital. ANIMALS Forty-six retired racing Greyhounds (RRGs) diagnosed with primary appendicular bone tumors that underwent limb amputation were included in the study. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Thirteen of 46 RRGs (28%) included in the study had delayed postoperative bleeding starting 48-72 h after surgery. Bleeding episodes included cutaneous, subcutaneous, and external bleeding that extended from the area of the surgical site that became widespread within hours, and that required administration of blood components. A paired t-test suggests that there was a significant decrease in PCV postoperatively for both dogs that bled and dogs that did not bleed (P < 0.0001). Forty of 46 RRGs (86%) received either fresh frozen plasma (FFP) or EACA or both, for the prevention of postoperative bleeding. A logistic regression model determined that dogs that did not receive EACA were 5.7 times more likely to bleed than dogs that did receive EACA, when controlling for whether or not they received FFP (95% CI: 1.02-32.15, P = 0.047). CONCLUSION This retrospective study suggests that preemptive postoperative administration of EACA appears to be efficacious in decreasing the frequency of bleeding in RRGs undergoing limb amputation; however, a prospective study is warranted to corroborate its effectiveness.