Establishment of reference intervals for kaolin-activated thromboelastography in dogs including an assessment of the effects of sex and anticoagulant use.

Tissue factor (TF)- and kaolin-activated thromboelastography (TEG) have been performed in a small number of healthy dogs, but reference intervals have not been assessed in a larger number of dogs. The goal of the current study was to establish reference intervals and assess intra-assay repeatability for kaolin-activated TEG in dogs. Additionally, the impact of sex and the influence of anticoagulant (native blood vs. recalcified citrate anticoagulated blood) were evaluated. Thromboelastography analyses were performed in 56 healthy dogs including German Shepherd Dogs (n = 19), Beagles (n = 15), and others (n = 22). Median age was 2 years (range: 1-6 years) and sex was evenly distributed (31 males and 25 females). To establish reference intervals, citrated whole-blood samples were collected, and TEG was performed 1 hr after sampling. Five TEG variables (R = reaction time; K = clot formation time; alpha = angle alpha; MA = maximal amplitude; G-value reflecting clot stability) were evaluated, and reference intervals were defined as the mean +/- 1.96-fold standard deviation. Intra-assay repeatability was assessed by calculating the pooled variance estimate in duplicate measurements of 6 healthy dogs. The effect of anticoagulant was assessed in 17 specimens. Reference intervals were as follows: R = 1.8-8.6 min; angle alpha = 36.9-74.6 degrees; K = 1.3-5.7 min; MA = 42.9-67.9 mm, and G = 3.2-9.6 Kdyn/cm(2). Coefficients of variation for R, K, angle alpha, MA, and G were 7.6%, 17.7%, 7.4%, 2.9%, and 6.6%, respectively. There was no significant impact of sex or anticoagulant on results. Interindividual variation was higher in native samples than in citrated whole blood. A limitation of the current study was that most of the samples were obtained from Beagles and German Shepherd Dogs. This study provides useful reference intervals for kaolin-activated TEG.

Reference intervals and method optimization for variables reflecting hypocoagulatory and hypercoagulatory states in dogs using the STA Compact automated analyzer.

Reference intervals for coagulation parameters have been rarely determined in dogs for the STA Compact automated coagulation analyzer, so it is the aim of the current study to validate assays and establish reference ranges for its use in canine specimens. Coagulation parameters were assessed in 56 healthy dogs with a median age of 2 years and evenly distributed sex. The 95% reference intervals were as follows: 1-stage prothrombin time = 5.7-8.0 sec; activated partial thromboplastin time (APTT) = 10.0-14.3 sec; thrombin time (TT) = 11.9-18.3 sec; fibrinogen = 1.3-3.1 g/l; antithrombin (AT) = 107.9-128.0%; D-dimer = 0.023-0.65 microg/ml; anti-factor Xa = 0.04-0.26 IU/l; and activated protein C (APC) ratio = 2.0-3.0. Protein C and S activity was markedly below (<-20%) and factor VIII was 2- to 11-fold above the human calibration standard, so a standard curve had to be prepared from canine pooled plasma. Reference intervals for protein C, protein S, and factor VIII were 75.5-118.9%, 74.4-160.5%, and 70.9-136.4%, respectively, compared with a canine standard curve. Streptokinase-activated plasminogen assay was not suitable for dogs. There was no significant impact of sex on hemostasis test results. Factor VIII activity, AT, protein C, protein S, and APC ratio were overestimated in hemolytic plasma, whereas fibrinogen, TT, and APTT were underestimated. Lipemia resulted only in false-high D-dimers. This study provided useful reference intervals for dogs, but some human tests (i.e., protein C, protein S, factor VIII, and plasminogen) required modification.

Evaluation of platelet count and its association with plateletcrit, mean platelet volume, and platelet size distribution width in a canine model of endotoxemia.

BACKGROUND: Platelets are of great importance in the pathogenesis of endotoxemia. Although thrombocytopenia is used as a diagnostic sign of endotoxemia, changes in values for platelet indices (plateletcrit [PCT], mean platelet volume [MPV], and platelet size distribution width [PDW]) in response to endotoxin are still unknown. OBJECTIVE: The aim of this study was to evaluate platelet count and its relations with platelet indices in a canine model of endotoxemia. METHODS: Twenty dogs were divided into 2 groups of 10 each, and treated intravenously with Escherichia coli endotoxin (1 mg/kg) or vehicle. Venous blood samples were collected before treatment (0 hour) and 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after treatment. Platelet counts and indices were determined on a CELL-DYN hematology analyzer. RESULTS: The platelet count and PCT decreased by a mean of 73% and 93%, respectively (P<.001), at 0.5 hour, and remained 70% and 85% lower than baseline values (P<.001) for 24 hours after endotoxin injection. MPV and PDW increased by a mean of 28% and 45%, respectively (P<.01), at 0.5 hour, and remained increased by 7% and 16% over baseline values for 24 hours (P<.01-.001). Platelet count correlated positively with PCT (P<.001), but correlated negatively with MPV (P<.001) and PDW (P<.01). CONCLUSIONS: Changes in platelet count and its association with platelet indices may reflect changes in platelet production and reactivity. Platelet indices have potential value in the diagnosis and monitoring of dogs and humans with endotoxemia.

Tei index (myocardial performance index) and cardiac biomarkers in dogs with parvoviral enteritis.

Tei index (myocardial performance) and cardiac biomarkers were evaluated in dogs with parvoviral enteritis (PVE). Tei index was calculated as isovolumic contraction time plus isovolumic relaxation time divided by ejection time. Myocardial and skeletal muscle damages were assessed by serum levels of cardiac troponin I (cTnI), creatine (phospho) kinase, lactate dehydrogenase and aspartate aminotransferase. Serum magnesium level was also determined. According to treatment response, dogs were divided into the survivor (n=20) and non-survivor groups (n=23). Seven healthy dogs served as controls. The mean value of the Tei index was higher in non-survivors, compared with survivors (p<0.02) and healthy controls (p<0.01). Serum level of cTnI in non-survivors was higher than that of survivors and controls (p<0.05). Tei index showed the highest sensitivity and specificity to predict mortality. The findings of an elevated Tei index and an increase in serum cTnI are factors associated with a poor prognosis in cases of canine parvovirosis.

Adiponectin and IGF-1 are negative acute phase proteins in a dog model of acute endotoxaemia.

The objective of this study was to evaluate the influence of an experimentally induced acute inflammation on serum adiponectin and insulin-like growth factor 1 (IGF-1) levels in the dog, and to compare their evolution with other well-established acute phase proteins (APPs) such as C-reactive protein (CRP), and haptoglobin (Hp). Therefore levels of adiponectin, IGF-1 and a profile of APPs were measured in healthy dogs after intravenous administration of E. coli LPS (0.02 mg/kg) and compared with dogs injected with saline solution (0.2 mL/kg). Adiponectin and IGF-1 were both decreased in response to endotoxins in the dog. Significant positive correlations were found between adiponectin and IGF-1 (r=0.31; p<0.05). Adiponectin had also a significant negative correlation with CRP (r=-0.39; p<0.05) and Hp (r=-0.27; p<0.05), whereas IGF-1 had significant negative correlation with CRP (r=-0.52; p<0.001). The results obtained in the present study indicate that adiponectin and IGF-1 behave as negative acute phase proteins after acute inflammatory stimulus in dogs.

Effect of hemolysis on canine kaolin-activated thromboelastography values and ADVIA 2120 platelet activation indices.

BACKGROUND: The impact of hemolysis on thromboelastography (TEG) and platelet activation indices has not been evaluated. OBJECTIVE: The aim of this study was to investigate the influence of hemolysis induced mechanically (HM) and hemolysis induced by freezing (HF) on TEG, platelet counts (PLT), and platelet activation indicators. METHODS: Blood from 17 dogs was divided into the following samples: controls, HM, and HF. HM was induced by 20 repetitions of expulsion of blood through a 23 g needle. Freezing was at -80 degrees C, followed by warming to 37 degrees and dilution with equal parts room temperature blood at 22 degrees C. TEG variables that were examined included reaction time (R), coagulation time (K), angle (alpha), maximum amplitude (MA), and clot rigidity (G). Platelet indices were measured with the ADVIA 2120 hematology analyzer. RESULTS: Hematocrit (HCT) (mean+/-SD) for controls, HM, and HF were 0.41+/-0.02, 0.39+/-0.03, and 0.25+/-0.02 L/L, respectively, consistent with decreases in HCT of 4.8% (HM) and 39.0% (HF). HM resulted in decreased R (2.5+/-0.9 minutes compared with 5.2+/-1.9 minutes for controls; P<0.001), and HF resulted in increased K (15.2+/-8.6 minutes compared with 5.3+/-4.0 minutes in controls; P<0.01) and decreased alpha (20+/-11 degrees compared with 46+/-17 degrees in controls; P<0.001). MA was decreased more in HF samples (26+/-2 mm) than in HM (38+/-8 mm) or control samples (49+/-9 mm; P<0.0001). The same applied to G values. PLT decreased after HM but not after HF. Hemolysis of both types resulted in decreased mean platelet component (MPC) concentration: control, 19.3+/-2.0, HM 15.5+/-3.4, and HF 14.3+/-0.7 g/dL (P<0.0001). CONCLUSION: In hemolyzed samples decreased MPC and R suggested activated primary and secondary hemostasis, respectively, but decreased MA and G indicated reduced clot firmness, possibly due to hyporeactive platelets. TEG and platelet activation indices should be interpreted cautiously after hemolysis.

Choline or CDP-choline attenuates coagulation abnormalities and prevents the development of acute disseminated intravascular coagulation in dogs during endotoxemia.

Sepsis/endotoxemia causes platelet dysfunctions, abnormalities in coagulation and hemostatic mechanisms leading to organ dysfunctions and mortality. Choline prevents organ injury and improves survival during endotoxemia. The main objective of the present study was to determine the effects of choline or cytidine-5'-diphosphocholine (CDP-choline) on endotoxin-induced activation of coagulation and development of disseminated intravascular coagulation (DIC). Dogs were treated intravenously (i.v.) with saline, choline (20 mg/kg), or CDP-choline (70 mg/kg) three times with 4-h intervals starting 5 min before i.v. injection of endotoxin (1 mg/kg). Platelet counts and functions, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, coagulation factors, D-dimer and antithrombin (AT) were measured before and at 0.5-96 h after endotoxin. Circulating platelet, fibrinogen, coagulation factors and AT were decreased, whereas PT and aPTT were prolonged and serum D-dimer levels were elevated after endotoxin. Endotoxin-induced reductions in platelet counts and functions, fibrinogen, coagulation factors and AT were attenuated or blocked by choline or CDP-choline. Choline or CDP-choline blocked endotoxin-induced prolongation in PT and aPTT and enhancement in D-dimer. Elevated DIC scores were attenuated by choline and blocked by CDP-choline. Choline administration increased serum choline concentrations and caused bradycardia. Choline also increased choline and acetylcholine contents of circulating mononuclear cells and inhibited radioligand binding to their cholinergic receptors. These data show that choline administration, as choline chloride or CDP-choline, restores the abnormalities in the primary, secondary, and tertiary hemostasis and prevents the development of DIC during experimental endotoxemia in dogs probably by increasing both neuronal and non-neuronal cholinergic activity.