Comparison of coagulation and fibrinolysis in Irish Wolfhounds and age-matched control dogs using tissue plasminogen activator-augmented viscoelastic testing.

OBJECTIVE: To determine if Irish Wolfhounds (IWs), like other sighthounds, are hyperfibrinolytic compared with nonsighthound dogs using 2 native and tissue plasminogen activator (tPA)-enhanced viscoelastic assays, one that is whole blood-based (viscoelastic coagulation monitor [VCM]) and the other that is plasma-based thromboelastography (TEG). DESIGN: Cohort study. SETTING: University teaching hospital. ANIMALS: A convenience sample of 27 IWs recruited from the Irish Wolfhound Association of New England Specialty and the local community, and 27 healthy, age-matched, large-breed control dogs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Blood samples including CBC, biochemistry, traditional coagulation, and viscoelastic testing were collected from IWs and control dogs. Twelve IWs had viscoelastic testing. IWs had lower fibrinogen concentrations (215.5 ± 57.8 vs 251.4 ± 64.5 mg/dL, P = 0.034) and formed weaker clots on both whole-blood VCM and plasma TEG assays (maximum clot firmness [VCM-MCF] = 39.4 [25.1-48.8] vs 48.5 [34.6-57.3], P = 0.0042; maximum amplitude [TEG-MA] = 22.7 [14.7-33.6] vs 32.2 [26.9-42.0], P < 0.0001). IWs were hyperfibrinolytic compared with control dogs on VCM whole-blood assays, with 25 U/mL tPA (lysis at 30 min [VCM-LI30] = 68.1 [0-100] vs\ 99.9 [63.3-100], P = 0.0009; lysis at 45 min [VCM-LI45] = 31.0 [0-100] vs 98.1 [38.4-100], P = 0.0002) but hypofibrinolytic compared with controls on TEG plasma assays with 50 U/mL tPA (lysis at 30 min [TEG-LY30] = 45.7 [4.6-94.6] vs 93.7 [12.3-96.5], P = 0.0004; lysis at 60 min [TEG-LY60] = 68.7 [29.7-96.8] vs 95.7 [34.4-97.6], P = 0.0003). Minimal fibrinolysis was measured on whole-blood VCM or plasma TEG assays without the addition of tPA, and there were no differences between the 2 groups. CONCLUSIONS: Weaker clots were found in IWs than control dogs. With the addition of tPA, IWs had evidence of hyperfibrinolysis on whole-blood VCM assays and hypofibrinolysis on plasma TEG assays compared with control dogs. Without the addition of tPA, however, both groups of dogs showed minimal fibrinolysis on viscoelastic testing.

Kaolin activation of recalcified citrated whole blood in a point-of-care viscoelastic coagulation test.

The viscoelastic coagulation monitor (VCM) is described as a point-of-care analyzer relying on activation of fresh whole blood (FWB) via contact between 2 glass plates. Kaolin is used as an activator in thromboelastography to reduce variability and shorten clotting times. The goal of this study was to compare VCM results from kaolin-activated, recalcified citrated samples with that from FWB. The VCM testing was performed using FWB and kaolin-activated, recalcified citrated samples. The VCM results were recorded for clot time (CT; seconds), clot formation time (CFT; seconds), alpha (degree), amplitude at 10 and 20 minutes (A10 and A20; VCM units), maximum clot firmness (MCF; VCM units), and lysis index (LI; %). Values were compared using a t-test or Wilcoxon-Mann-Whitney test, with a P-value < 0.05 considered significant. Variability between samples was calculated using Levene's test. The VCM kaolin activation resulted in significantly faster CT and CFT (P < 0.0001), higher alpha angle (P < 0.001), and higher A10 and A20 (P = 0.007, P = 0.015) compared to FWB. There was no difference in MCF, LI30, or LI45. There was no difference in variability identified. The addition of kaolin to recalcified citrated whole blood VCM samples results in more rapid clotting of FWB alone and could be considered for clinical use in dogs.

Le moniteur de coagulation viscoélastique (VCM) évalue l'hémostase au point de service en utilisant du sang entier frais activé au contact de deux disques de verre. Le kaolin est un activateur utilisé en thromboélastographie pour réduire la variabilité et raccourcir le temps de coagulation.Le but de cette étude était de comparer les résultats du VCM obtenus sur des échantillons citratés recalcifiés et activés par du kaolin, avec ceux obtenus sur sang entier frais. Les échantillons sanguins ont été prélevés sur des chiens sains. Les tests avec le VCM ont été réalisés sur des échantillons de sang entier frais et sur des échantillons de sang citraté recalcifié et activé par du kaolin. Les résultats du VCM ont été enregistrés : temps de coagulation (CT; secondes), temps de formation du caillot (CFT; secondes), angle alpha (degrés), amplitude à 10 et 20 minutes (A10 et A20; unités VCM), fermeté maximale du caillot (MCF; unités VCM), index de lyse à 30 et 45 minutes après la MCF (LI; pourcentage). Les valeurs ont été comparées à l'aide d'un un test t apparié ou un test de Wilcoxon-Mann-Whitney, avec une valeur P < 0,05 considérée comme significative. La variabilité entre les échantillons a été calculée à l'aide d'un test de Levene.Les résultats du VCM réalisé sur les échantillons activés par du kaolin présentaient une diminution significative du CT et CFT (P < 0,0001) ainsi qu'une augmentation significative de l'angle alpha (P < 0,001) et de A10 et A20 (P = 0,007, P = 0,015). Aucune différence n'a été démontrée dans la MCF, l'index LI30 ou LI45. Aucune différence de variabilité n'a été identifiée.L'ajout du kaolin aux échantillons VCM de sang entier citraté recalcifié aboutit à une activation de la coagulation plus rapide que par simple contact avec les disques de verre et pourrait être envisagé pour l'usage clinique chez le chien.(Traduit par les auteurs).

Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period.

BACKGROUND: The viscoelastic coagulation monitor (VCM Vet) is a novel, portable device that provides a global assessment of hemostasis. The study aims were to evaluate serial viscoelastic analysis during the perianesthetic period in healthy dogs and to compare the agreement between two VCM Vet devices. Twenty healthy dogs undergoing orthopedic surgery were enrolled. Whole blood samples were collected from an intravenous catheter at four time points: baseline, 15 min after premedication, 60 min after inhalant initiation, and 60 min after inhalant termination. Viscoelastic tests were performed in duplicate on different devices, providing: clot time (CT; seconds), clot formation time (CFT; seconds), alpha angle (α; degrees), amplitude (units) at 10 (A10) and 20 (A20) minutes post clot time, maximum clot firmness (MCF; units), and lysis index (%) at 30 (Li30) and 45 (Li45) minutes post maximum clot formation. RESULTS: One hundred sixty samples were analyzed. The speed of CT and CFT significantly decreased an average of 25.5 s (95% confidence interval [CI]15.9-35.0) and 6.9 s (95% CI 3.1-10.7) per time point, respectively. There were no significant changes in clot strength or lysis variables. The Bland-Altman style plot shows an acceptable rate of agreement for all variables with intra-class correlation ranging from 0.64-0.94. CONCLUSION: The rate of clot formation (CT and CFT) decreased over the perianesthetic period in healthy dogs undergoing surgery. These changes were small and occurred without changes in clot strength or fibrinolysis rate, thus were not clinically relevant. There was clinically acceptable consistency between devices.

Evaluation of hemostasis in hyperthyroid cats.

BACKGROUND: Hyperthyroid cats might have a predisposition to arterial thrombus formation. The mechanism for thrombogenesis currently is unknown but could be associated with systemic hypercoagulability as seen in hyperthyroid humans. OBJECTIVE: Our purpose was to evaluate markers of hemostasis in hyperthyroid cats compared to healthy cats, and in hyperthyroid cats before and after radioactive iodine treatment (RIT). ANIMALS: Twenty-five cats with hyperthyroidism and 13 healthy euthyroid cats >8 years of age. METHODS: Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, antithrombin (AT), D-dimers, thrombin-antithrombin complexes (TAT), von Willebrand Factor antigen (vWF : Ag), and activity of factors VIII and IX were measured. An echocardiogram was performed in all cats. Hemostatic markers and echocardiogram were evaluated again 6 to 9 months after successful RIT in 7 cats. RESULTS: Hyperthyroid cats had higher fibrinogen concentration (P < .0001), AT activity (P < .0001), and vWF : Ag concentration (P = .01) than healthy control cats with all results decreasing significantly post-RIT. Hyperthyroid cats were not more likely to be in a hypercoaguable state than euthyroid cats (P = .08). Serum T4 concentration was not a predictor of a hypercoagulable state (P = .53). CONCLUSIONS AND CLINICAL IMPORTANCE: Hyperthyroid cats have evidence of altered hemostasis that does not appear to be solely attributable to cardiac abnormalities, but no evidence of a hypercoagulable state. Findings suggest altered hemostasis resolves after RIT. Hyperthyroid cats could have endothelial dysfunction as indicated by increased vWF : Ag which could potentiate thrombogenesis.

Comparison of STA-NeoPTimal (Stago) and STA-Neoplastine CI Plus (Stago) thromboplastin reagents using a STA Satellite Max analyzer to measure prothrombin times in dogs.

BACKGROUND: Different thromboplastins are available to measure prothrombin time (PT). Stago coagulation analyzers and reagents are currently used in veterinary laboratories and enable PT measurements to explore the coagulation cascade (extrinsic pathway). OBJECTIVES: The main objective was to compare PT measurements obtained with the STA-NeoPTimal reagent with the commonly used STA-Neoplastine CI Plus reagent. The secondary objective was to compare the PT ratio with the international normalized ratio (INR) calculated from our derived clotting times. METHODS: Analytical performance was evaluated with intra-assay and inter-assay precision. Seventy-two individual canine plasma samples were collected. Each sample was tested with both thromboplastins, using an STA Satellite Max analyzer. The PT, PT ratio, and INR values obtained with the two reagents were compared using Passing-Bablok regression for correlations and Bland-Altman plots for method agreements. RESULTS: The analytical performance of STA-NeoPTimal reagent was acceptable. Compared with the STA-Neoplastine CI Plus reagent, the STA-NeoPTimal reagent showed a positive proportional bias for PT values. Narrow range analyses showed good agreement for normal PT values (less than 9.5 seconds, internal reference cutoff with STA-Neoplastine CI Plus), and clinical concordance was achieved. When PT was prolonged (more than 9.5 seconds), PT increases were more marked with the STA-NeoPTimal reagent. Agreement was good for INR values across the whole range of PT results. CONCLUSION: STA-NeoPTimal can be reliably implemented in veterinary laboratories for canine PT measurements, as agreement between the PT results measured with the two reagents was clinically acceptable.

Diagnosis of primary hyperfibrinolysis and in vitro investigation of the inhibitory effects of tranexamic acid in a group of dogs with sarcomas - A pilot study.

Primary hyperfibrinolysis is not well characterised in canine cancer. This prospective case-control pilot study aimed to evaluate tissue plasminogen activator-modified thromboelastography (tPA-TEG) for diagnosis of primary hyperfibrinolysis in dogs with cancer and establish the in vitro therapeutic concentration of tranexamic acid (TXA). Nine dogs with sarcomas and normocoagulable thromboelastograms and 11 healthy dogs were included. For each a whole blood tPA-TEG, and four tPA-TEGs with added TXA in different concentrations were analysed. Lysis percentage at 30/60 min following maximal amplitude (LY30/60), clot lysis index (CL30/60), maximum rate of lysis (MRL), and total lysis (L) were investigated as diagnostic parameters of primary hyperfibrinolysis. In vitro TXA concentrations needed to inhibit 50% (IC50) and 90% (IC90) of the fibrinolytic potential were compared between groups. Significant primary hyperfibrinolysis (LY30 (P = 0.0001), LY60 (P = 0.003), CL30 (P = 0.01), and L (P = 0.02)) was observed in dogs with sarcomas. IC50 and IC90 of in vitro TXA for normalizing LY30 were 13.34 (SE 1.52) and 31.10 (SE 3.01) mg/L for dogs with sarcomas and 4.41 (SE 5.84) and 20.00 (SE 6.18) mg/L for healthy dogs. IC50 and IC90 for normalizing LY60 were 22.18 (SE 1.27) and 58.94 (SE 5.47) mg/L for dogs with sarcomas and 11.25 (SE 2.82) and 56.20 (SE 11.61) mg/L for healthy dogs. The IC50 for LY60 was significantly increased for dogs with sarcomas (P = 0.0003). Primary hyperfibrinolysis was documented by tPA-TEG in dogs with sarcomas. In vitro IC50 and IC90 for TXA were established. Clinical studies are required to establish therapeutic dosages in vivo.

Blood loss and coagulation profile in pregnant and non-pregnant queens undergoing elective ovariohysterectomy.

OBJECTIVES: The aims of this study were to determine if there is increased risk of intraoperative bleeding in pregnant cats undergoing elective ovariohysterectomy (OHE), and to compare coagulation in queens in various stages of estrus and pregnancy subjected to elective OHE using a whole-blood viscoelastic assay. METHODS: Intraoperative blood loss was compared between non-pregnant and pregnant cats undergoing elective OHE. Viscoelastic evaluations of whole blood drawn pre- and postoperatively were performed using a point-of-care device measuring clot time (CT), clot formation time (CFT), alpha angle, maximum clot formation (MCF), amplitude at 10 and 20 mins (A10 and A20, respectively), and lysis index at 30 and 45 mins after MCF (LI30 and LI45, respectively). RESULTS: One hundred and ninety-three cats underwent OHE by a ventral midline approach. Median blood loss was greater for pregnant cats (2.0 ml, range <0.5-13 ml) than non-pregnant cats (<0.5 ml, range <0.5-15 ml; P <0.0001). Preoperatively, pregnant cats had a shorter median CFT (165 s vs 190.5 s), increased median A10 (31 from 25.5 VCM units) and A20 (38 from 35 VCM units), and a lower median LI45 (99% from 100%) than non-pregnant cats. Postoperatively, A10 and A20 increased, and LI30 and LI45 decreased in both non-pregnant and pregnant queens. In pregnant queens, mean CT also increased postoperatively. CONCLUSIONS AND RELEVANCE: Pregnant cats were relatively hypercoagulable and had an increased rate of clot lysis than non-pregnant cats. Intraoperative blood loss was increased in pregnant vs non-pregnant cats, but no clinically relevant bleeding conditions occurred.

Comparison of viscoelastic test results from blood collected near simultaneously from the jugular and saphenous veins in cats.

OBJECTIVES: The aim of this study was to compare viscoelastic test results from samples collected from a jugular vein using a 20 G needle and a medial saphenous vein using a 22 G needle in cats presenting for elective ovariohysterectomy (OHE) or castration. METHODS: Forty apparently healthy cats (20 males and 20 females) presenting for elective OHE or castration were included in a prospective study observing viscoelastic test results from central and peripherally collected whole blood. Cats were anesthetized during blood collection with a standardized protocol including buprenorphine, ketamine, dexmedetomidine and isoflurane. Blood samples from jugular and saphenous veins were collected near simultaneously. Viscoelastic evaluations of whole blood were performed using a point-of-care device measuring clot time (CT), clot formation time (CFT), alpha angle (α), maximum clot formation (MCF), and amplitude at 10 and 20 mins (A10 and A20, respectively). Viscoelastometry continued post-clot time to determine a lysis index at 30 and 45 mins (LI30 and LI45, respectively) to assess fibrinolysis. RESULTS: Studied cats had a median age of 18 months (range 5 months to 5 years) and a median weight of 3.6 kg (range 2.7-5.9 kg). A total of 80 samples were available for analysis. While lysis indices were not different, viscoelastic measures of coagulation differed between sampling sites (CT, P <0.005; CFT, P = 0.01; α, P <0.05; MCF, P <0.0005; A10, P <0.0005; A20, P <0.0005). CONCLUSIONS AND RELEVANCE: Viscoelastic results from jugular venous blood samples appear to be more hypercoagulable than those collected from the medial saphenous vein, suggesting that the same site should be used consistently for serial monitoring or for collecting study data.

Decreased antithrombin activity and inflammation in cats.

OBJECTIVES: The objective of this study was to determine if inflammatory markers are associated with antithrombin activity in cats. METHODS: For a retrospective population of 231 cats admitted to a referral hospital, antithrombin activity was classified as decreased (n = 77), intermediate (n = 97) or in the upper quartile (n = 57). Odds ratios (ORs) were calculated for an association between decreased or upper quartile activity and hypoalbuminemia, hyperfibrinogenemia, band neutrophilia and toxic change. Multiple logistic regression was performed to determine if an association between band neutrophilia and decreased antithrombin activity was independent of decreased hepatic synthesis, consumptive coagulopathy or protein loss. RESULTS: Cats with decreased antithrombin activity were more likely than cats with intermediate-to-upper quartile activity to have band neutrophilia (OR 2.85, P = 0.0050), hypoalbuminemia (OR 12.1, P <0.0001) or toxic neutrophils (OR 4.47, P <0.0001). Cats with antithrombin activity in the upper quartile were less likely than those with intermediate-to-low activity to have hypoalbuminemia (OR 0.31, P = 0.0023) or toxic neutrophils (OR 0.44, P = 0.033). In a regression model that included other mechanisms for decreased antithrombin, band neutrophilia remained associated with decreased antithrombin activity (adjusted OR 2.62, P = 0.013). CONCLUSIONS AND RELEVANCE: Contrary to previous studies suggesting antithrombin is a feline positive acute phase protein, this study demonstrates an association between decreased antithrombin activity and inflammation. Further studies are needed to determine the mechanistic basis of this association.

Thromboelastography in cats with cholestatic liver disease.

OBJECTIVES: While thromboelastography (TEG) has helped define a complex state of hemostasis in dogs and humans with hepatobiliary disease, it has not been explored in cats with cholestatic liver disease (CLD). The objective of this study was to describe TEG parameters in cats with CLD and to compare these parameters with conventional plasma-based coagulation tests, white blood cell (WBC) count and biochemical indicators of liver disease grade and severity. METHODS: Eighteen cats with CLD, defined by a serum bilirubin ⩾3 mg/dl and a greater than two-fold increase in serum alanine aminotransferase (ALT) and/or alkaline phosphatase (ALP) activity, were prospectively enrolled. All cats received vitamin K1 subcutaneously for 24-36 h prior to acquisition of blood for kaolin-activated TEG analysis, prothrombin time (PT) and activated partial thromboplastin time (aPTT). Patient total solids, packed cell volume, platelet count, WBC count, and serum liver enzymes and bilirubin were extracted from the medical record and correlated with coagulation test results. RESULTS: TEG global clot strength (TEG G) values defined 9/18 (50%), 5/18 (28%) and 4/18 (22%) cats as hypercoagulable, normocoagulable or hypocoagulable, respectively. TEG G was significantly negatively correlated with PT, aPTT and serum ALP activity and positively correlated with total solids. Five cats (5/18, 28%) were hyperfibrinolytic with clot lysis at 60 mins (LY 60) >15.3%. LY 60 was significantly positively correlated with PT. CONCLUSIONS AND RELEVANCE: By TEG analysis, cholestatic cats replete with vitamin K1 display a variety of coagulation profiles. Indications of synthetic failure (prolonged PT and aPTT) were associated with hypocoagulable and hyperfibrinolytic TEG parameters. High disease activity (serum ALP) was associated with a hypocoagulable state.

A prospective randomized open-label trial on the comparative effects of 6% hydroxyethyl starch 130/0.4 versus polyionic isotonic crystalloids on coagulation parameters in dogs with spontaneous hemoperitoneum.

OBJECTIVE: To evaluate the effects of 6% hydroxyethyl starch 130/0.4 (HES) and a polyionic isotonic crystalloid (CRYS) on standard coagulation tests and rotational thromboelastometry (ROTEM) in dogs with spontaneous hemoperitoneum (SHP). DESIGN: Prospective randomized open-label clinical study. SETTING: University teaching hospital. ANIMALS: Forty-two client-owned dogs presented with SHP. INTERVENTIONS: Dogs diagnosed with SHP and hypovolemic shock were randomly allocated to receive HES (10 mL/kg, n = 22) or CRYS (30 mL/kg, n = 20) intravenously over 20 minutes for hemodynamic stabilization. MEASUREMENTS AND MAIN RESULTS: Parameters measured before (T0 ) and after (T1 ) treatment were HCT, platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen concentrations, and extrinsic activated (EXTEM), intrinsic activated (INTEM), and extrinsic activated with platelet inhibition ROTEM assays. Data were analyzed as absolute values and as the percentage change from T0 to T1 . No significant differences between groups were detected in any variable at T0 , and for HCT, platelet counts, prothrombin time, activated thromboplastin time, and fibrinogen concentrations at T1 . Clot formation time in EXTEM was significantly prolonged (P = 0.037), and maximum clot firmness was significantly decreased (P = 0.038) in the HES group compared to the CRYS group at T1 . The percentage change in EXTEM clotting time (P = 0.012) and INTEM clot formation time (P = 0.031) was greater after HES than CRYS. Lysis indices remained at 100% for all ROTEM assays in both groups. CONCLUSION: Compared to a 3-fold volume of CRYS, administration of HES was associated with impairment in ROTEM parameters in dogs with SHP, but no evidence of hyperfibrinolysis was detected.

Investigation of pathological haemorrhage in Maine Coon cats.

OBJECTIVE: Afibrinogenaemic haemorrhage was previously reported in a Maine Coon cat. Two littermates subsequently died from surgical non-haemostasis, suggesting a hereditable coagulopathy. METHODS: We prospectively recruited cats which were: a) Maine Coons with pathological haemorrhage (group 1, n=8), b) healthy familial relatives of group 1 (group 2, n=13) and c) healthy Maine Coons unrelated to groups 1 and 2 (group 3, n=12). Coagulation tests: prothrombin time, activated partial thromboplastin time and thrombin clotting time (TCT) were performed on citrated plasma along with quantification of fibrinogen. Routine haematological examination was performed on EDTA-anticoagulated blood collected contemporaneously. RESULTS: Thirty-three blood samples were analysed. Fibrinogen concentrations were significantly reduced in groups 1 (P<0.01) and 2 (P<0.01) compared with group 3. Similarly, TCT was found to be significantly extended in group 1 (P<0.01) and group 2 (P=0.02) with respect to group 3. CONCLUSIONS: Dysfibrinogenaemia was identified in clinical cases and their healthy relatives, suggesting that this may represent a hereditary condition of Maine Coon cats. Clinicians should be aware of the increased potential for non-haemostasis in this cat breed and consider assessing clotting function before (elective) surgery.

Comparison of the prothrombin time-derived and Clauss assays for the measurement of plasma fibrinogen in hospitalized dogs.

BACKGROUND: Accurate measurement of fibrinogen is necessary for detecting bleeding tendencies and inflammation. The Clauss assay determines fibrinogen concentration from its inverse relationship with thrombin-induced clot times. PT-derived assays determine fibrinogen concentrations from changes in the optical density during a routine prothrombin assay and allow determination of fibrinogen without additional reagents. This method has not been assessed in clinically ill dogs. OBJECTIVES: We aimed to determine the agreement between the Clauss and PT-derived fibrinogen assays and compare the ability of the assays to predict surgery-associated transfusions and discriminate between dogs with and without bleeding. METHODS: Retrospective medical record review identified 200 dogs with a variety of underlying diseases with results from both assays. The two assays were compared using Passing-Bablok regression, and the ability of the assays to identify bleeding and predict the need for transfusions was assessed with receiver operating characteristic (ROC) curve analyses. RESULTS: The PT-derived assay displayed constant (y-intercept, 32 mg/dL; 95% CI 18-41) and proportional (slope, 0.79; 95% CI 0.75-0.82) bias compared with the Clauss assay. The Clauss assay reported lower values than the PT-derived assay at lower fibrinogen concentrations and higher values at higher concentrations. Comparing the area under the ROC curve did not detect significant differences in the ability of the two assays to discriminate between dogs with and without bleeding or predict the need for surgery-associated transfusions. CONCLUSIONS: The PT-derived and Clauss assays are not interchangeable, and the Clauss assay could be more sensitive to hypofibrinogenemia in dogs.

Outcome and treatments of dogs with aortic thrombosis: 100 cases (1997-2014).

BACKGROUND: Aortic thrombosis (ATh) is an uncommon condition in dogs, with limited understanding of risks factors, outcomes, and treatments. OBJECTIVES/HYPOTHESIS: To describe potential risk factors, outcome, and treatments in dogs with ATh. ANIMALS: Client-owned dogs with a diagnosis of ATh based on ultrasonographic or gross necropsy examination. METHOD: Multicentric retrospective study from 2 academic institutions. RESULTS: One hundred dogs were identified. Anti-thrombin diagnosis, 35/100 dogs were nonambulatory. The dogs were classified as acute (n = 27), chronic (n = 72), or unknown (n = 1). Fifty-four dogs had at least one comorbidity thought to predispose to ATh, and 23 others had multiple comorbidities. The remaining 23 dogs with no obvious comorbidities were classified as cryptogenic. Concurrent illnesses potentially related to the development of ATh included protein-losing nephropathy (PLN) (n = 32), neoplasia (n = 22), exogenous corticosteroid administration (n = 16), endocrine disease (n = 13), and infection (n = 9). Dogs with PLN had lower antithrombin activity than those without PLN (64% and 82%, respectively) (P = .04). Sixty-five dogs were hospitalized with 41 subsequently discharged. Sixteen were treated as outpatient and 19 euthanized at admission. In-hospital treatments varied, but included thrombolytics (n = 12), alone or in combination with thrombectomy (n = 9). Fifty-seven dogs survived to discharge. Sixteen were alive at 180 days. Using regression analysis, ambulation status at the time of presentation was significantly correlated with survival-to-discharge (P < .001). CONCLUSIONS/CLINICAL IMPORTANCE: Dogs with ATh have a poor prognosis, with nonambulatory dogs at the time of presentation having worse outcome. Although the presence of comorbid conditions associated with hypercoagulability is common, an underlying cause for ATh was not always identified.

Coagulation parameters in hyperthyroid cats before and after radioiodine treatment compared with healthy controls.

OBJECTIVES: The aim of the study was to describe the coagulatory state of hyperthyroid cats before and after successful radioiodine therapy (RIT) compared with healthy age-matched controls, using classical coagulation parameters and thromboelastogram (TEG) as a global assessment method. The differences in coagulation activity after RIT, depending on the thyroid hormone (normal vs low total thyroxine [T4]) state, were also evaluated. METHODS: Fifteen hyperthyroid cats and 10 healthy age-matched controls were recruited. Hyperthyroid cats that remained hyperthyroid 14 days after RIT were excluded. Haematology, biochemistry, T4, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and TEG were assessed in control cats and hyperthyroid cats before and 7 and 14 days after RIT. Two weeks after successful RIT, further comparisons were made between cats with normal T4 vs those with low T4. RESULTS: Fourteen days after successful RIT, 7/15 cats had normal T4 and 8/15 had low T4. Thrombocytosis was noted in 6/15 cats after treatment. Fibrinogen was significantly higher (P <0.001) and PT shorter (P <0.01) in the hyperthyroid cats compared with the healthy controls and these changes persisted after RIT. Persistent increases in fibrinogen, PT, TEG maximal amplitude and TEG clot rigidity, reflecting clot stability, after RIT primarily occurred in the cats with normal T4. TEG-K (time until preset amplitude of 20 mm is reached) and alpha (α) angle reflected impaired fibrin cross-linking ability prior to RIT, which significantly increased after therapy (P <0.05). CONCLUSIONS AND RELEVANCE: Based on some of the coagulation parameters, cats with hyperthyroidism showed hypercoagulable tendencies, which were mildly increased after RIT, possibly due to transient radiation-induced thyroiditis.

Retrospective characterization of canine coagulopathies using the turbidimetric ACL-TOP 300 analyzer (2014-2015): Forty-seven dogs.

OBJECTIVE: To characterize disseminated intravascular coagulation (DIC), liver failure (LF), post-hepatic cholestasis (PHC), and anticoagulant rodenticide intoxication (ROD) in dogs using an immunoturbidimetric coagulation analyzer and to characterize the relationship between clinical bleeding and bleeding parameters. DESIGN: Retrospective study (August 2014-July 2015). SETTING: University teaching hospital. ANIMALS: Forty-seven client-owned dogs diagnosed with DIC (n = 24), LF (n = 9), PHC (n = 5), or ROD (n = 9) based on history, clinical pathology, cytology, histopathology. or exploratory surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Median prothrombin time (PT), activated partial thromboplastin time (aPTT), and quantitative fribrinogen assay (QFA) were above the reference interval for DIC, LF, PHC and ROD with the exception of a normal QFA for LF. Clot curve analysis for DIC was characterized by elevated PT Delta, PT first derivative, and aPTT Delta, and normal for aPTT second derivative; all LF parameters were within the RI; all PHC parameters were above the RI; and ROD had elevated aPTT delta, but low aPTT second derivative. Coagulopathic bleeding recognized within the DIC group was characterized by median PT delta in mABS (milliabsorbance), first derivative and aPTT delta values in mABS within the RI at 35.0, 55.5 and 38, respectively. The nonbleeding DIC group median values of these same parameters were 189.5, 586.5 and 288, respectively. CONCLUSIONS: The classically utilized indicators of secondary hemostasis, PT and aPTT, were prolonged within all 4 groups; DIC, LF, PHC and ROD as expected. Fibrinogen concentration was increased in both PHC and ROD, decreased in LF and increased but with a bimodal distribution in DIC that correlated with clinical bleeding. The degree of PT and aPTT prolongation did not correlate with clinical bleeding in the DIC group, however clot curve analysis, did reveal an association.

Ex vivo evaluation of the efficacy of canine fresh-frozen plasma thawed using a microwave plasma defroster.

BACKGROUND: Commercial microwave plasma defrosters (MPDs) are used globally in human medicine to safely thaw fresh-frozen plasma (FFP), but this technology has never been tested in a veterinary setting. This study was undertaken to assess the efficacy of a commercial MPD for the rapid thawing of canine FFP. STUDY DESIGN: Twenty-three units (twelve 120 mL and eleven 240 mL) of canine FFP were thawed using an MPD. Time-to-thaw and pre- and postthawing temperatures of the units were measured. Clotting factor activities (factors II, V, VII, VIII, IX, X, and von Willebrand factor), fibrinogen concentrations, prothrombin times, and activated partial thromboplastin times were measured. KEY FINDINGS: The evaluated MPD effectively thaws plasma quickly for both 120 mL units (2.7 ± 0.08 min) and 240 mL units (3.9 ± 0.15 min) while maintaining clinically relevant activities of clotting factors and fibrinogen concentration. While some measurements of factor VIII activity fell below the reference interval, none fell below 40%. One 240 mL unit had von Willebrand factor activity <70%. There was no evidence of excessively heated plasma to indicate a safety concern. SIGNIFICANCE: The MPD evaluated in this study provides a useful means to rapidly thaw canine FFP for correction of factor-deficient coagulopathy.

Variability of tissue factor-activated thromboelastography and whole blood impedance platelet aggregometry in healthy dogs.

OBJECTIVE: To assess interindividual (CVG ) and intraindividual (CVI ) variability over time for results of thromboelastography (TEG) and whole-blood impedance platelet aggregometry in healthy dogs. ANIMALS: Six healthy Beagle dogs. MEASUREMENTS AND MAIN RESULTS: Tissue factor (TF)-activated TEG and adenosine diphosphate (ADP) and arachidonic acid (AA)-induced whole blood impedance platelet aggregometry were performed at 3 different time points (days 1, 4, and 6). In addition, platelet count, hematocrit, and plasma fibrinogen concentrations were recorded each study day. Activated partial thromboplastin time, one-stage prothrombin time, antithrombin activity, and D-dimer concentrations were measured on the first day of the study. For TEG, the variables reaction time (R), clotting time (K), rate of clot formation (α), and maximum amplitude (MA) were recorded. For platelet aggregometry, the areas under the curve for ADP (AUCADP )- and AA (AUCAA )-induced aggregation were measured. The CVI was lower than the CVG over time for MA, AUCADP , and AUCAA ; however, the CVI was higher than the CVG for the TEG variables R, K, and α. There were no statistical differences in the platelet count, hematocrit, and fibrinogen measurements over time. CONCLUSIONS: In healthy dogs, a subject-based reference interval for ADP- and AA-induced platelet aggregometry and the TEG variable MA provide a more sensitive method to detect changes. However, due to the high CVI , population-based reference intervals may be more appropriate for interpretation of the TEG variables R, K, and α.

An apparent case of brodifacoum toxicosis in a whelping dog.

A 7-y-old Weimaraner bitch was presented to emergency service after 3 h of active labor with no puppies produced. Hemoabdomen and hemothorax were present at the time of surgery; prothrombin time (PT) and activated partial thromboplastin time (aPTT) were both found to be within normal ranges. Surgical cesarean section was performed; 4 dead puppies and 5 live puppies were delivered. Because hemostasis was difficult to achieve, a hysterectomy was performed; however, the dog died as the operation was being completed. At autopsy, the pleural cavity contained 1.5 L of unclotted blood; the peritoneal cavity was relatively normal, and no obvious hemorrhage was associated with the surgical sites. All 4 dead fetuses were opened, and their pleural cavities were filled with unclotted blood. An anticoagulant screen was performed, and brodifacoum was identified in the liver of the bitch. This case is unusual in that the PT and aPTT were within reference intervals, but brodifacoum was present in sufficient amounts to potentially result in this dog bleeding to death, and also is suspected to have crossed the placenta and caused hemothorax and death in 4 of 9 puppies in utero.

[Vergleichende Bestimmung von Gerinnungsparametern in Blutproben verschiedener Wild- und Ziervogelspezies]. / Comparative aspects of blood coagulation measurements in various wild and captive bird species.

OBJECTIVE: Information about the influence of species variety or diseases on coagulation values in avian blood is rare. The aim of this study was to assess the influence of species on measurements of coagulation parameters in avian plasma samples using commercially available reagents and to investigate potential influences of selected diseases on clotting times. MATERIAL AND METHODS: Prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin time (TT) were measured in citrated plasma of healthy individuals collected from eight different wild and captive avian species applying currently commercially available reagents prepared for use in humans, which were preselected in preliminary studies. The same parameters were tested in plasma samples from birds affected by aspergillosis, atherosclerosis, neoplasia and traumata. RESULTS: PT and aPTT showed a high interspecies variety. Irrespective of species, aPTTs were extremely long and partially exceeded the measurement range limit. Minor variations between species were seen in TT measurements. Clotting times obtained from birds affected by aspergillosis, atherosclerosis and neoplasia were not significantly different when compared to healthy birds. Plasma obtained from traumatised individuals showed significantly shorter PT and aPTT than that in healthy birds. CONCLUSION AND CLINICAL RELEVANCE: Differences between species must be considered in diagnostic coagulation measurements in avian blood. Regardless of the avian species, aPTT measurements on avian samples appear to be of limited value. Lower PT and aPTT values reflect coagulation activation in traumatised birds.