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OBJECTIVE: Rivaroxaban is a new anticoagulant option for dogs, yet its reported oral bioavailability is as low as 60%. The objective of this study was to examine the influence of feeding and gastroprotectant medications on the bioactivity (anti‐Xa activity) of rivaroxaban in healthy dogs. DESIGN: Prospective experimental study. SETTING: University research laboratory. ANIMALS: Five healthy neutered male purpose‐bred Beagles. INTERVENTIONS: Dogs were administered a median dose of 1.8 mg/kg rivaroxaban (range, 1.6‐1.8 mg/kg) orally once daily for 2 consecutive days with either (1) no food, (2) food, (3) sucralfate 30 minutes before rivaroxaban, or (4) omeprazole at the same time as rivaroxaban. Blood was collected from preplaced jugular catheters immediately before and at 6 time points after rivaroxaban administration (2, 4, 8, 24, 36, and 48 hours). A rivaroxaban calibrated anti‐Xa activity assay (RIVA) was used to monitor anticoagulant effect. MEASUREMENTS AND MAIN RESULTS: Rivaroxaban administration resulted in significant increases in RIVA (P = 0.02), with peak activities occurring 2 to 4 hours after dosingduring each study arm. No feeding was associated with significantly higher RIVA at the 36‐hour time point compared to all other treatment arms (P

OBJECTIVE To document if a transient hypercoagulable state occurs in healthy dogs following abrupt cessation of unfractionated heparin (UFH) therapy. DESIGN Prospective experimental pilot study. SETTING University research facility. ANIMALS Seven adult random-source male dogs. INTERVENTION Thromboelastography (TEG) and thrombin-antithrombin (TAT) complex formation were used to assess coagulation status in healthy dogs. Seven adult research dogs received 200-300 IU/kg subcutaneous UFH every 8 hours for 4 days. A final IV bolus of 100 IU/kg was given on day 4 and the peak measured heparin concentration 1 hour later is defined as the start of heparin withdrawal (time 0). Citrated whole blood samples were collected at baseline (prior to heparin administration) and 3, 6, 12, 30, and 48 hours after UFH withdrawal. At all time points, a kaolin-activated TEG was performed and citrated plasma for measurement of TAT concentration was collected for batch analysis. Fibrinogen concentration, PCV, total plasma proteins, and platelet count were measured at baseline and 48 hours after heparin withdrawal. MEASUREMENTS AND MAIN RESULTS Compared to baseline, TAT was increased 12 hours after heparin withdrawal and returned to baseline by 30 hours. TEG clot formation time (K) was decreased 30 and 48 hours after heparin withdrawal. CONCLUSION TAT results suggest that a transient increase in thrombin generation developed 12 hours after withdrawal of UFH therapy. Though clot kinetics were rapid compared to baseline beginning 30 hours after heparin withdrawal, a return to baseline was not documented. Future studies are warranted to determine the clinical relevance of these results and to evaluate the effect of UFH withdrawal in critically ill animals.

Objective To compare the Lactate Plus handheld monitor to a reference blood gas analyzer for determining plasma lactate concentrations in canine whole blood. Design Prospective observational study. Setting University teaching hospital. Animals Ninety-four dogs hospitalized or admitted through the emergency service provided 125 blood samples. Only dogs that required a venous or arterial blood gas evaluation as a part of their diagnostic assessment or ongoing management were included. Interventions None. Measurements and Main Results Canine whole blood samples were assayed for plasma lactate concentration with a reference blood gas analyzer and the Lactate Plus monitor. Correlation and Bland–Altman analyses were used to compare results between the 2 methods. A subset of blood samples was repeatedly analyzed with the Lactate Plus to assess monitor precision. Plasma lactate measurements from the Lactate Plus monitor showed excellent correlation with those from the reference analyzer (ρ = 0.98, P 5 mmol/L. The coefficient of variation ranged from 0–26.2% (median, 3.7%) and was

Objective To characterize the correlation between thromboelastography (TEG) variables using strong activators and anti-Xa (AXa) activity in healthy dogs administered subcutaneous unfractionated heparin (UFH). Design Prospective experimental study. Setting University research facility. Animals Eight adult random-source male dogs. Intervention Dogs were randomized to receive subcutaneous UFH at 200, 250, or 300 IU/kg every 8 hours for a total of 10 injections. Blood samples were collected at time 0 (preheparin) and 3, 6, and 8 hours after the 1st (Day 1) and 10th (Day 4) UFH injection. After the 8-hour blood sample was obtained on day 4, a 100 IU/kg IV bolus of UFH was administered and an additional blood sample was collected 1 hour later (hour 9). AXa activity, activated partial thromboplastin time (aPTT), and TEG (with up to 5 activators) were performed at each time point. Modes of activation for TEG included recalcified (Ca), Ca with heparinase (CaH), CaH and tissue factor 1:3600 (CTF3600H), Ca with tissue factor 1:100 (CTF100), and RapidTEG. Spearman rank correlations were calculated for each of the aforementioned parameters and the AXa activity. P-values were corrected for multiple comparisons with a Bonferroni correction. Measurements and Main Results Significant correlations were found between AXa activity and the TEG R values generated with CTF100 (R = 0.83, P ≤ 0.0001) and RapidTEG (R = 0.90, P < 0.0001), as well as both forms of aPTT measurement (R = 0.86 and 0.84, P < 0.0001). Conclusions This study demonstrates that TEG variables derived using robust activation correlate with AXa activity as well as aPTT and have the potential to be used for monitoring UFH therapy in healthy dogs. Future studies are warranted to evaluate its diagnostic utility in critically ill animals.

Objective To examine available evidence on prehospital care in human and veterinary trauma and emergency medicine and develop best practice guidelines for use by both paramedical and nonparamedical personnel in the approach to the prehospital care of dogs and cats. Design Systematic evaluation of the literature gathered via medical databases searches of Medline, CAB abstracts, and Google Scholar. Synthesis From a review and systematic evaluation of the available evidence, consensus guidelines on the approach to prehospital care of dogs and cats in 18 scenarios were developed. Conclusions Due to the lack of current evidence in the veterinary prehospital arena, best practice guidelines were developed as an initial platform. Recommendations were based on a review of pertinent human and available veterinary literature as well as a consensus of the authors’ professional opinions. It is anticipated that evidence-based additions will be made in the future.

Objective To describe the clinical features, diagnostic findings, treatment, and outcome of a dog with acute abdominal pain and hemoperitoneum secondary to a presumptive intraperitoneal (IP) snakebite. Case Summary A 10-month-old castrated male mixed-breed dog was evaluated for suspected snake envenomation. The dog presented recumbent and tachycardic with signs of severe abdominal pain. Two cutaneous puncture wounds and hemoperitoneum were discovered during evaluation. Ultrasonographic examination revealed communication of the wounds with the peritoneal cavity. The dog was treated with supportive care, parenteral analgesia, packed red blood cell and fresh frozen plasma transfusions, crotalid antivenom, and placement of an IP catheter to provide local analgesia. The dog recovered fully and was discharged 5 days after initial presentation. New or Unique Information Provided To our knowledge, this is the first report of IP envenomation accompanied by hemorrhage treated with continuous IP analgesia in the veterinary literature.

Objective To characterize hemostasis and determine if disseminated intravascular coagulation (DIC) is present in cats with cytauxzoonosis. Design Cross-sectional study. Setting University teaching hospital. Animals Five client-owned cats with cytologic and PCR-confirmed cytauxzoonosis. Interventions None. Measurements and Main Results Admission samples were collected for hemostasis testing including platelet count, activated partial thromboplastin time, prothrombin time, fibrinogen, antithrombin (AT), d-dimer, protein C, plasminogen, antiplasmin, factors VII, VIII, IX, X, and XI, von Willebrand factor, and thromboelastography. Results were compiled for combined criteria used to define DIC, and all 5 cats satisfied criteria using a previously described modified scoring system for DIC in cats. The abnormalities found in all 5 cats included thrombocytopenia, low protein C activity, and prolonged prothrombin time; however, none of the cats had low AT activity. None of the cats had clinical signs of hemorrhage despite thrombocytopenia, coagulation factor deficiency (5/5 cats), and thromboelastographic evidence of hypocoagulability (2/5 cats). Three of 5 cats survived to hospital discharge. The nonsurvivors had disseminated cytauxzoonosis with schizont-laden macrophages in vessels of various organs. Conclusions This is the first report that comprehensively describes the hemostastic status of cats with naturally occurring infection with Cytauxzoon felis. All 5 cats had laboratory evidence of overt DIC. Unlike human and canine models of sepsis-induced DIC, AT deficiency was not found in this series of cats. Further research is warranted to investigate therapeutic strategies targeting thrombotic DIC to improve survival in cats with cytauxzoonosis.

Objective To systematically examine evidence surrounding definitions and reporting of data for viscoelastic testing in veterinary medicine. Design Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality, and development of consensus on conclusions for application of the concepts to clinical practice. Setting Academic and referral veterinary medical centers. Results Databases searched included Medline, CAB abstracts, and Google Scholar. Conclusions All 4 standard thromboelastography (TEG) and rotational thromboelastometry (ROTEM) variables should be universally reported, and the reporting of shear elastic modulus in addition to maximum amplitude (MA) is encouraged. There is insufficient evidence to support universal usage of the coagulation index at this time. The K value and clot formation time are the most variable of the 4 parameters, with alpha angle, MA, and maximum clot firmness generally the least variable. Individual studies should report sufficient data on patients and institutional controls to enable definitions of hypo- and hypercoagulability to be evaluated post-hoc, and it is recommended that all studies specifically report how these conditions were defined. In reporting data relating to fibrinolysis, the TEG variables LY30, LY60, CL30, CL60, and the ROTEM variables LI30, LI60, ML, LOT, and LT should be documented. Studies should report sufficient data on patients and controls to enable definitions of hyper- and hypofibrinolysis to be evaluated post-hoc, and we suggest that standard TEG/ROTEM assays may be unable to detect hypofibrinolysis in companion animals. We recommend that every center establish reference intervals, which are specific to either TEG or ROTEM. These reference intervals should be established using veterinary clinical pathology guidelines, standardized protocols, and a minimum of 40 healthy animals. There are currently insufficient data in companion animals to suggest a utility for Vcurve variables beyond that of standard TEG variables.

Objective To systematically examine the evidence relating to the performance of rotational viscoelastic testing in companion animals, to develop assay guidelines, and to identify knowledge gaps. Design Multiple questions were considered within 5 parent domains, specifically system comparability, sample handling, assay activation and test protocol, definitions and data reporting, and nonstandard assays. Standardized, systematic evaluation of the literature was performed. Relevant articles were categorized according to level of evidence and assessed for quality. Consensus was developed regarding conclusions for application of concepts to clinical practice. Setting Academic and referral veterinary medical centers. Results Databases searched included Medline, Commonwealth Agricultural Bureaux abstracts, and Google Scholar. Worksheets were prepared evaluating 28 questions across the 5 domains and generating 84 assay guidelines. Conclusions Evidence-based guidelines for the performance of thromboelastography in companion animals were generated through this process. Some of these guidelines are well supported while others will benefit from additional evidence. Many knowledge gaps were identified and future work should be directed to address these gaps and to objectively evaluate the impact of these guidelines on assay comparability within and between centers.

Objectives To describe coagulation abnormalities in dogs following severe acute trauma and to evaluate the relationship between coagulation, clinical, and laboratory variables, and disease and injury severity, as well as the ability of coagulation variables to predict the presence of body cavity hemorrhage (BCH), necessity of blood product administration, and outcome. Design Prospective, multicenter, observational study. Setting Two university teaching hospitals. Animals Forty client-owned dogs sustaining severe blunt or penetrating trauma. Interventions Blood samples were collected within 12 hours of the traumatic incident for measurement of blood gases, lactate concentration, platelet count, activated clotting time, prothrombin time, activated partial thromboplastin time (aPTT), fibrinogen concentration, antithrombin activity, D-dimer concentration, protein C activity, plasmin inhibition, plasminogen activity, and kaolin-activated thomboelastography. Results Decreased platelet count was a risk factor for the presence of BCH (P = 0.006) and decreased platelet count (P < 0.001), protein C activity (P = 0.001), angle (α) (P = 0.001), maximum amplitude (MA) (P < 0.001), and clot strength (G) (P = 0.002) were risk factors for blood product administration. Nonsurviving dogs were hypocoagulable with prolonged aPTT (P = 0.008), decreased plasmin inhibition (P = 0.033), decreased α (P = 0.021), and decreased MA (P = 0.038) compared to surviving dogs. Multivariate analysis accounting for disease severity showed that prolonged aPTT (P = 0.004, OR = 1.74) was the strongest predictor of nonsurvival. Prolonged aPTT was positively correlated with APPLE-fast score (P < 0.001, r2 = 0.35), lactate concentration (P < 0.001, r2 = 0.35), and negative base excess (P = 0.001, r2 = 0.27). Acute traumatic coagulopathy, as defined by 2 or more abnormal coagulation tests, was diagnosed in 15% of dogs at hospital admission and was more common in dogs with increased disease severity (P = 0.002), decreased systolic blood pressure (P = 0.002), and increased lactate concentration (P = 0.011). Conclusions In dogs with severe traumatic injuries and hypoperfusion, measurement of thromboelastography and aPTT should be considered to support clinical assessments in predicting the need for blood product administration and nonsurvival.

Objective – To determine whether the dose of antivenin administered is associated with a difference in survival of crotalid-envenomated dogs. A secondary objective was to determine whether other covariables affect survival. Design – Retrospective study (1988–2006). Setting – Private referral center and university small animal teaching hospital. Animals – Two hundred and eighteen dogs with evidence of crotalid envenomation and treatment with equine-derived antivenin. Interventions – Administration of antivenin. Measurements and Main Results – Patient signalment, physical and clinicopathologic data at time of presentation, treatments, complications of antivenin therapy, length and cost of hospitalization, and outcome were recorded. Confidence intervals were determined for the difference in median number of vials administered and for median dosage for patients that lived versus died. Penalized logistic regression was performed to evaluate the effect of other covariables on survival. The median age of affected dogs was 3 years (range 6 w–12 y) with a median weight of 25.7 kg (range 1.95–86.4 kg). The median number of antivenin vials administered was 1.0 (range 1.0–10.0). Acute and chronic reactions were reported in 7% (16/218) and 0.9% (2/218) of dogs, respectively. Nine of 218 dogs (4.1%) died. The median number of vials administered to the nonsurvivors and survivors were 2.0 (range 1–5 vials) and 1.0 (range 1–10 vials), respectively. The median number of vials received was significantly different in dogs that died versus those that lived (P

Objective: To describe a case of fatal anaphylaxis in a dog associated with a ‘routine’ dexamethasone suppression test. Case summary: An 8-year-old, spayed female dog, was treated with parenteral dexamethasone for a diagnosis of immune-mediated thrombocytopenia. The dog had responded to treatment, but 9 months later was evaluated for endogenous hyperadrenocorticism, prior to surgery for a ruptured anterior cruciate ligament. A normal ACTH stimulation test was followed by a high-dose dexamethasone suppression test. Immediately following the intravenous injection of dexamethasone, the dog developed severe anaphylactic shock and died. The postmortem examination findings supported the diagnosis of anaphylaxis. New information provided: The anaphylaxis in this dog was fulminating and by-passed the usual early signs of drug hypersensitivity. This is the first case in the veterinary literature reporting on dexamethasone as the cause of this dog's catastrophic event.