Assessment of the relationships among coagulopathy, hyperfibrinolysis, plasma lactate, and protein C in dogs with spontaneous hemoperitoneum

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.

The effect of ε-aminocaproic acid on blood product requirement, outcome and thromboelastography parameters in severely thrombocytopenic dogs

BACKGROUND

No treatment other than platelet administration is known to protect against spontaneous hemorrhage in thrombocytopenic dogs.

OBJECTIVES

Primary: determine if treatment with ε-aminocaproic acid (EACA) decreases the requirement for blood transfusions and improves outcome in dogs with severe thrombocytopenia. Secondary: find evidence of hyperfibrinolysis and determine the effect EACA administration on rapid (rTEG) and tissue plasminogen activator-spiked (tPA-rTEG) thromboelastography parameters.

ANIMALS

Twenty-seven dogs with severe thrombocytopenia were treated with EACA, and data from an additional 33 were obtained from the hospital database as historical control (HC) cohort.

METHODS

Single arm clinical trial with HCs. The EACA group dogs received EACA (100 mg/kg IV followed by a constant-rate infusion [CRI] of 400 mg/kg/24 hours). Thromboelastography before and during EACA infusion, hospitalization days, number of transfusions, and mortality were compared.

RESULTS

No difference was found in number of transfusions per dog (median, interquartile range; 1, 0-2.5 vs 0.9, 0-2; P = .5) and hospitalization days (4, 4-6 vs 4.5, 3.75-6; P = .83) between HC and EACA groups, respectively, and no difference in survival was identified by log-rank analysis (P = .15). Maximum amplitude on both rTEG and tPA-rTEG increased after EACA administration (rTEG baseline: 23.6, 9.6-38.9; post-EACA: 27.3, 19.8-43.2; P < .001; tPA-rTEG baseline: 23, 10.9-37.2; post-EACA: 24.7, 16.7-44.8; P < .002).

CONCLUSIONS AND CLINICAL IMPORTANCE

Although EACA increased clot strength, there was no effect on outcome. Treatment with EACA at this dosage cannot be recommended as a routine treatment but may be considered for dogs with severe ongoing hemorrhage.

Prospective evaluation of platelet function and fibrinolysis in 20 dogs with trauma

OBJECTIVES

To determine platelet function and assess fibrinolysis in dogs following trauma using multiple electrical impedance aggregometry and a modified thromboelastographic (TEG) technique. To determine if the severity of trauma, as assessed by the Animal Trauma Triage (ATT) score and clinicopathological markers of shock, is associated with a greater degree of platelet dysfunction and fibrinolysis.

SETTING

University teaching hospital.

ANIMALS

Twenty client-owned dogs with trauma (occurring <24 h prior to admission and blood sampling) and ATT score of >4 were prospectively recruited. A control group of 10 healthy dogs was included.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Platelet function was measured using multiple electrode platelet aggregometry (MEPA) utilizing arachidonic acid, ADP, and collagen agonists. Fibrinolysis was assessed in citrated whole blood with the addition of tissue plasminogen activator (tPA; 50 U/mL) using kaolin-activated TEG. Conventional statistical analysis was performed to compare coagulation parameters between the groups and assess linear correlations. Median (interquartile range) ATT score was 5 (5-7), and 65% (n = 13) of dogs suffered polytrauma. Mean (± SD) time from trauma to blood sampling was 9 hours (± 6). Median (interquartile range) shock index and plasma lactate concentration were 1.1 (0.7-2.0, n = 16) and 2.9 mmol/L (0.9-16.0, n = 18), respectively. Four dogs did not survive to discharge (20%). There were no differences between the trauma and control group coagulation variables. A moderate negative correlation between ATT score and area under the curve for ADP was found (P = 0.043, r2  = -0.496).

CONCLUSIONS

Preliminary evaluation of platelet function measured by MEPA, and fibrinolysis measured by tPA-modified TEG, is not significantly different in this population of dogs with traumatic injury compared to healthy dogs.

A prospective evaluation of the prevalence of thromboemboli and associated hemostatic dysfunction in dogs with carcinoma or sarcoma

BACKGROUND

Knowledge of the prevalence of thromboemboli and the associated hemostatic status in dogs with carcinoma or sarcoma is unknown and might allow earlier intervention.

OBJECTIVES

Estimate prevalence of thromboemboli and their association with hemostatic changes in dogs with carcinomas or sarcomas; estimate predictive values of hemostatic variables for thromboembolic disease in tumor-bearing dogs.

ANIMALS

Thirty-two dogs with sarcoma, 30 with carcinoma, 20 healthy age-controlled dogs.

METHODS

Prospective cross-sectional study. A hemostasis panel (platelet concentration, thromboelastography, fibrinogen and D-dimer concentration, factor X, VII and antithrombin activity) was performed in all dogs. Tumor-bearing dogs underwent complete post mortem and histopathological evaluation. Comparisons between healthy dogs and tumor-bearing dogs with and without intracavitary hemorrhage; and tumor-bearing dogs with and without microthrombi were analyzed.

RESULTS

Thromboembolic disease was identified in 32/62 (52%, 95% CI: 39%-65%) tumor-bearing dogs. Microthrombi were identified in 31/62 (50%, 95% CI: 37%-63%) dogs, 21/31 (68%, 95% CI: 49%-83%) had exclusively intra-tumoral microthrombi, 10/31 (32%, 95% CI: 17%-51%) had distant microthrombi. Macrothrombi were identified in 3 tumor-bearing dogs. Hemostatic changes potentially consistent with overt and non-overt disseminated intravascular coagulation were identified in some tumor-bearing dogs. D-dimer concentrations were significantly higher (P = .02) and platelet concentration significantly lower (P = .03) in tumor-bearing dogs with microthrombi compared to tumor-bearing dogs without microthrombi. D-dimer concentration above 500 ng/mL was 80% sensitive and 41% specific for the prediction of microthrombi presence.

CONCLUSION

The high microthrombi prevalence and concomitant hemostatic dysfunction in dogs with carcinomas or sarcomas has not previously been reported, though the clinical importance is unknown. Increased D-dimer concentration might increase suspicion of microthrombi.

Reference Range of Kaolin-Activated Thromboelastography (TEG) Values in Healthy Pet Rabbits (Oryctolagus cuniculus)

Thromboelastography (TEG) is a viscoelastic technique that allows the examination of both cellular and plasma protein clotting factors. Thromboelastography helps to investigate the underlying coagulopathy and to monitor therapeutic modalities. Although viscoelastic techniques have been used in human and veterinary medicine, reference ranges in pet rabbits are missing. The objective of this study is to establish the reference-range values of TEG parameters in healthy pet rabbits. 24 healthy pet rabbits of different breeds were included: 16 crossbreeds, four Californians, two lops, one lionhead, and one angora. Four rabbits were less than one year old and 20 were older than one year. Twelve rabbits were neutered females, 10 neutered males, and two were intact females. Health status was assessed through a physical examination, a complete blood work, and a coagulation profile. A TEG 5000 Thromboelastograph Hemostasis System was used with kaolin-activated citrated whole blood. All samples were analysed 30 min postextraction. The TEG reference ranges were reaction time (R) 1.4-6.9 min; clot formation time (K) 0.8-2.2 min; α angle 65.8-82.2 degrees; maximal amplitude (MA) 53.7-73.5 mm; measure of clot strength/firmness (G-value) 5796.6-13,885.9 dyn/cm²; and percentage of clot lysis in 30 min (LY30%) 0-41.5%. This study provides the reference ranges of TEG in pet rabbits.

Clinical Use of Canine Thawed Refrigerated Plasma: A Historical Case Series

Thawed plasma (TP) refers to defrosted fresh frozen plasma stored refrigerated. TP is used in human medicine for the rapid provision of coagulation factors and resuscitation of haemorrhagic shock, but its use in dogs is poorly described. The objectives of this historical case series were to describe the reasons for TP transfusion, treatment outcomes, and adverse events associated with canine TP transfusions in a veterinary teaching hospital. We hypothesised that TP would be used most commonly for the treatment of haemorrhage secondary to anticoagulant rodenticide intoxication and trauma. Blood bank plasma transfusion logs were searched to identify dogs that received at least one unit of TP between December 2015 and June 2021. Briefly, 166 dogs received a total of 262 units of TP. Anticoagulant rodenticide intoxication (37/166, 22.3%) was the most common reason for transfusion, followed by traumatic haemorrhage (23, 13.9%) and spontaneous haemoperitoneum (22, 13.2%). The majority of dogs received one unit of TP (111/166, 67.1%) and pRBCs were commonly simultaneously transfused with TP (65, 39.2%). Severe prolongations of prothrombin time and activated partial thromboplastin time were reduced following TP transfusions. Allergic reactions were the most common transfusion reaction (19/166, 11.4%). Most dogs survived to discharge (101/166, 60.8%).

Hemostatic profiles in dogs with sudden acquired retinal degeneration syndrome

BACKGROUND

Sudden acquired retinal degeneration syndrome (SARDS) is a common cause of irreversible blindness in dogs. It bears clinical resemblance to hypercortisolism, which can be associated with hypercoagulability. The role of hypercoagulability in dogs with SARDS is unknown.

OBJECTIVE

Determine hemostatic profiles in dogs with SARDS.

ANIMALS

Prospective pilot study: Dogs with a history of SARDS (n = 12). Prospective case-control study: Dogs with recent onset of SARDS (n = 7) and age-, breed-, and sex-matched controls (n = 7).

METHODS

Prospective pilot study: We performed thromboelastography (TEG). Prospective case-control study: Dogs had CBC, serum biochemistry, urinalysis, TEG, fibrinogen concentration, antithrombin activity, D-dimers, thrombin-antithrombin complexes, and optical platelet aggregometry performed.

RESULTS

Prospective pilot study: 9/12 dogs with a history of SARDS were hypercoagulable with increased TEG G value and 2/3 had hyperfibrinogenemia. Case-control study: All dogs with SARDS and 5/7 controls were hypercoagulable based on TEG G value. Dogs with SARDS had significantly higher G values (median, 12.7 kdynes/s; range, 11.2-25.4; P = .04) and plasma fibrinogen concentration (median, 463 mg/dL; range, 391-680; P < .001) compared to controls.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hypercoagulability was common in both dogs with SARDS and controls, but dogs with SARDS were significantly more hypercoagulable on TEG. The role of hypercoagulability in the pathogenesis of SARDS remains to be determined.

Biomarkers of Coagulation and Inflammation in Dogs after Randomized Administration of 6% Hydroxyethyl Starch 130/0.4 or Hartmann's Solution

Synthetic colloid fluids containing hydroxyethyl starch (HES) have been associated with impairment of coagulation in dogs. It is unknown if HES causes coagulation impairment in dogs with naturally occurring critical illness. This study used banked plasma samples from a blinded, randomized clinical trial comparing HES and balanced isotonic crystalloid for bolus fluid therapy in 39 critically ill dogs. Blood was collected prior to fluid administration and 6, 12, and 24 h thereafter. Coagulation biomarkers measured at each time point included prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen concentration, and the activities of coagulation factors V, VII, VIII, IX, and X, von Willebrand factor antigen, antithrombin, and protein C. Given the links between coagulation and inflammation, cytokine concentrations were also measured, including interleukins 6, 8, 10, and 18, keratinocyte-derived chemokine, and monocyte chemoattractant protein-1. Data were analyzed with linear mixed effects models. No significant treatment-by-time interactions were found for any biomarker, indicating that the pattern of change over time was not modified by treatment. Examining the main effect of time showed significant changes in several coagulation biomarkers and keratinocyte-derived chemokines. This study could not detect evidence of coagulation impairment with HES.

Transient Postoperative Hemorrhage from Elbow Arthroscopy Portals following Intra-Articular Pentosan Polysulfate Sodium Injection

Four adult, client owned dogs with diagnosed bilateral elbow dysplasia undergoing elbow arthroscopy for removal of fragmented medial coronoid process were identified via a retrospective database search, who also received intra-articular administration of pentosan polysulfate sodium (PPS) (Cartrophen Vet, Biopharm Australia Pty Ltd., Bondi Junction, New South Wales). Dogs had postoperative administration of 5 ml PPS injected into each elbow joint following elbow arthroscopy. Within 1-3 hours of administration, each dog experienced hemorrhage from arthroscopy incisions that was determined to be independent of surgical trauma given lack of hemorrhage intraoperatively. Pressure bandages were placed, and the hemorrhage and elevated coagulation parameters resolved 12-18 hours following intra-articular injection. No further intervention was required, and the dogs were discharged 20-26 hours postoperatively. The purpose of this case series is to describe 4 dogs who experienced transient and focal hemorrhage following off-label intra-articular administration of pentosan polysulfate sodium (PPS). While this case series is limited due to small number of cases, results following bilateral, intra-articular injection of PPS support a transient systemic coagulopathy. Though this report represents administration of PSS via a route and at doses beyond that recommended on the label, results suggest that administration of PSS in the manner described in this report should be avoided.

Fibrinolysis in Dogs with Intracavitary Effusion: A Review

Simple Summary

In blood vessels there is a balance between clot formation and its dissolution. Fibrinolysis normally allows the breakdown of blood clots during the healing of injured blood vessels. This process is mediated by the activation of a blood enzyme (plasmin) which breaks down a meshed protein (fibrin) which holds blood clots at the site of the vessel injury. In some diseases, the activation of plasmin becomes excessive, leading to bleeding tendencies (hyperfibrinolysis). Under normal conditions, abdominal and thoracic cavities are filled with a small amount of fluid deriving from the blood. The results of recent studies have shown that, in dogs, all types of pathologic intracavitary fluids have an increased fibrinolytic activity. This increased fibrinolytic activity is also present in their blood, in some cases reaching a hyperfibrinolytic state. Hyperfibrinolysis and bleeding tendencies have also been documented in cardiopathic dogs with ascites. The latter result is surprising considering that thrombotic events are commonly documented in humans and cats with some cardiac diseases.

Abstract

Physiologic fibrinolysis is a localized process in which stable fibrin strands are broken down by plasmin in response to thrombosis. Plasmin activation can also take place separately from the coagulation process, resulting in pathologic fibrinolysis. When plasmin activation exceeds the neutralizing capacity of plasmin inhibitors, severe bleeding can potentially take place. Although the processes which regulate coagulation and fibrinolysis in the blood are well known, it is less clear as to what extent the same processes take place in the body cavities and whether they influence systemic hemostasis. The results of the studies herein cited demonstrate that coagulation followed by fibrinogenolytic/fibrinolytic activity takes place in all kinds of canine ascitic and pleural fluids. Moreover, systemic clotting abnormalities suggesting primary fibrinolysis/primary hyperfibrinolysis (i.e., elevated plasma fibrin/fibrinogen degradation products [FDPs] and normal D-dimer concentrations with fibrinogen concentrations ≤ 100 mg/dL or above this cut-off, respectively) occur in dogs with intracavitary effusion. Enhanced fibrinolytic activity in dogs with intracavitary effusion can also be detected using rotational thromboelastometry (ROTEM), although the degree of agreement between ROTEM and FDPs, D-dimer and fibrinogen concentrations is poor. Finally, contrary to the thrombotic events commonly documented in some humans and cats with cardiac diseases, bleeding tendencies due to primary fibrinolysis/primary hyperfibrinolysis have been documented in dogs with cardiogenic ascites.

Comparison of assessment of coagulation in healthy dogs by the TEG 6s and TEG 5000 viscoelastic analyzers

The TEG 6s (Haemonetics) point-of-care viscoelastic analyzer is portable, compact, simple to use, and has the potential for rapid viscoelastic analysis that can guide the treatment of veterinary patients at the site of care. Although approved for use in people, the TEG 6s has yet to be evaluated for hemostatic analysis in veterinary medicine. Citrated whole blood (CWB) was collected from 27 healthy dogs. An aliquot of CWB from each dog was diluted by 33% with an isotonic crystalloid, representing an in vitro model of hemodilution. Unaltered and diluted CWB samples were analyzed using 2 TEG 6s and 6 TEG 5000 (Haemonetics) analyzers. The 6 TEG 5000 analyzers ran duplicate analyses of either unaltered or diluted samples using 1 of 3 reagents (Haemonetics): Kaolin TEG, RapidTEG, or TEG Functional Fibrinogen. Duplicate TEG 5000 analyses were averaged and compared with a single TEG 6s analysis. Lin concordance correlation coefficient and Bland-Altman plots were used to evaluate agreement of reaction time, kinetic time, alpha angle, maximum amplitude (MA), and G value (G) for samples activated with Kaolin TEG, and agreement of MA for samples activated with RapidTEG between the 2 machines. Overall, agreement between the TEG 6s and TEG 5000 analyzers was poor. Viscoelastic measurements by the TEG 6s and TEG 5000 in healthy dogs were not all interchangeable. Agreement was satisfactory only for MA and G measurements of diluted blood samples activated with Kaolin TEG, and MA measurements for both unaltered and diluted blood samples activated with RapidTEG.

Pre-operative Hemostatic Status in Dogs Undergoing Splenectomy for Splenic Masses

Portal system thrombosis is a rare but potentially fatal complication of splenectomy in dogs. The mechanism behind development of post-operative portal system thrombosis is unclear but may include alterations of portal blood flow following surgery, acquired hypercoagulability and endothelial dysfunction. The aim of the study was to evaluate hemostatic biomarkers in hemodynamically stable (heart rate <130 beats/min, blood lactate < 2.5 mMol/L) and non-anemic (hematocrit >35%) dogs prior to splenectomy for splenic masses. Our hypothesis was that this population of stable dogs would have pre-existing laboratory evidence of hypercoagulability unrelated to shock, bleeding, anemia, or other pre-operative comorbidities. Pre-operatively, abdominal ultrasonography was performed and blood was collected for platelet enumeration, prothrombin time (PT), activated partial thromboplastin time (aPTT), kaolin-activated thromboelastography (TEG), fibrinogen, von Willebrand factor activity (vWF:Ag), antithrombin and thrombin-antithrombin complex (TAT). Histopathological diagnosis and 30-day survival were recorded. None of the 15 enrolled dogs had pre-operative sonographic evidence of portal system thrombosis. Three of fifteen dogs were thrombocytopenic, three had thrombocytosis, three were hyperfibrinogenemic, one had low vWF:Ag, three had mild prolongations of PT and none had abnormal aPTT. Based on the TEG G value, 13/15 dogs were hypercoagulable (mean ± SD 13.5 ± 5.4 kd/s). Antithrombin deficiency was identified in 9/15 dogs (mean ± SD 68.7 ± 22.7%) with 5/9 having concurrently elevated TAT suggesting active thrombin generation. No dogs developed portal system thrombosis and all achieved 30-day survival. Pre-operative hypercoagulability was recognized commonly but its association with post-operative thrombosis remains undetermined.

The Angiostrongylus vasorum Excretory/Secretory and Surface Proteome Contains Putative Modulators of the Host Coagulation

Angiostrongylus vasorum is a cardiopulmonary nematode of canids and is, among others, associated with bleeding disorders in dogs. The pathogenesis of such coagulopathies remains unclear. A deep proteomic characterization of sex specific A. vasorum excretory/secretory proteins (ESP) and of cuticular surface proteins was performed, and the effect of ESP on host coagulation and fibrinolysis was evaluated in vitro. Proteins were quantified by liquid chromatography coupled to mass spectrometry and functionally characterized through gene ontology and pathway enrichment analysis. In total, 1069 ESP (944 from female and 959 from male specimens) and 1195 surface proteins (705 and 1135, respectively) were identified. Among these were putative modulators of host coagulation, e.g., von Willebrand factor type D domain protein orthologues as well as several proteases, including serine type proteases, protease inhibitors and proteasome subunits. The effect of ESP on dog coagulation and fibrinolysis was evaluated on canine endothelial cells and by rotational thromboelastometry (ROTEM). After stimulation with ESP, tissue factor and serpin E1 transcript expression increased. ROTEM revealed minimal interaction of ESP with dog blood and ESP did not influence the onset of fibrinolysis, leading to the conclusion that Angiostrongylus vasorum ESP and surface proteins are not solely responsible for bleeding in dogs and that the interaction with the host's vascular hemostasis is limited. It is likely that coagulopathies in A. vasorum infected dogs are the result of a multifactorial response of the host to this parasitic infection.

Comparison of healthy blood donor Greyhounds and non-Greyhounds using a novel point-of-care viscoelastic coagulometer

OBJECTIVE

To measure and compare viscoelastic coagulation in 2 canine blood donor populations using a novel, point-of-care device (VCM Vet Analyzer, VCM).

DESIGN

Cohort study.

SETTING

Academic and commercial veterinary blood banks.

ANIMALS

Non-Greyhounds from community-based blood donor program and Greyhounds from a blood bank colony.

INTERVENTION

Blood was collected from all dogs via direct venipuncture for a complete hemogram, biochemistry, and point-of-care viscoelastic coagulation.

MEASUREMENT AND MAIN RESULTS

All biochemical measurements for all dogs in Group NG (n = 38, non-Greyhounds) and Group G (n = 53, Greyhounds) were within local reference intervals. Hematology data showed significant statistical differences between groups in hemoglobin, RBC, platelet, and WBC concentrations. Group G demonstrated lower maximum clot firmness (MCF) with 17 VCM units (26 VCM units in Group NG), increased lysis with 30 VCM units at 30 minutes (LI30) and 27 VCM units at 45 minutes (LI45) (86 VCM units LI30 and 85 VCM units LI45 in Group NG), and decreased amplitude of 13 VCM units 10 minutes (A10) after clot time (CT) and 6 VCM units 20 minutes after CT (A20) (18 VCM units [A10] and 22 VCM units [A20] in Group NG).

CONCLUSION

This study found differences between healthy Greyhound and non-Greyhound blood donors in measures of clot strength and fibrinolysis as measured by the VCM. Whereas Greyhound have unique hematologic and hemostatic profiles, these measured viscoelastic differences are important to note prior to and following surgical intervention to aid in clinical decision-making if bleeding complications develop.

The effect of analytical temperature on thromboelastography tracings in dogs

Viscoelastic testing methods such as thromboelastography (TEG) are becoming increasingly available to veterinarians in a clinical setting. TEG is useful in determining therapeutic transfusion needs and assessing global abnormalities of hemostasis of patients, given that it provides a more comprehensive assessment of coagulation than traditional tests. TEG is standardly performed at 37°C, which is considered a normal body temperature for human patients; however, 37°C is lower than normal body temperature for most canine patients. In an in vitro study, we investigated the potential effect that this difference in body temperature and test temperature might have on TEG results. Citrated blood samples were collected from clinically normal, as well as sick, dogs with various body temperatures. Samples were analyzed concurrently at the patient's body temperature and at 37°C. There was very high correlation between TEG performed at body temperature and at 37°C for R (min) and MA (mm), high correlation for K (min) and alpha angle (deg), and moderate correlation for LY30 (%) and LY60 (%). For canine patients with normal to mildly abnormal body temperatures, performance of TEG at the standard 37°C is acceptable.

Volume Resuscitation in the Acutely Hemorrhaging Patient: Historic Use to Current Applications

Acute hemorrhage in small animals results from traumatic and non-traumatic causes. This review seeks to describe current understanding of the resuscitation of the acutely hemorrhaging small animal (dog and cat) veterinary patient through evaluation of pre-clinical canine models of hemorrhage and resuscitation, clinical research in dogs and cats, and selected extrapolation from human medicine. The physiologic dose and response to whole blood loss in the canine patient is repeatable both in anesthetized and awake animals and is primarily characterized clinically by increased heart rate, decreased systolic blood pressure, and increased shock index and biochemically by increased lactate and lower base excess. Previously, initial resuscitation in these patients included immediate volume support with crystalloid and/or colloid, regardless of total volume, with a target to replace lost vascular volume and bring blood pressure back to normal. Newer research now supports prioritizing hemorrhage control in conjunction with judicious crystalloid administration followed by early consideration for administration of platelets, plasma and red blood during the resuscitation phase. This approach minimizes blood loss, ameliorates coagulopathy, restores oxygen delivery and correct changes in the glycocalyx. There are many hurdles in the application of this approach in clinical veterinary medicine including the speed with which the bleeding source is controlled and the rapid availability of blood component therapy. Recommendations regarding the clinical approach to volume resuscitation in the acutely hemorrhaging veterinary patient are made based on the canine pre-clinical, veterinary clinical and human literature reviewed.

Utility of the Sonoclot analyzer to assess hyperfibrinolysis in dogs

BACKGROUND

Coagulation abnormalities, including hyperfibrinolysis, have been documented in sick veterinary patients. Viscoelastic tests, including the Sonoclot Coagulation and Platelet Function Analyzer, are useful in detecting hyperfibrinolysis. Tissue plasminogen activator (tPA) assays have been used to quantify fibrinolysis using thromboelastography.

OBJECTIVES

We aimed to document and evaluate changes in the whole blood of healthy dogs exposed to in vitro tPA at varying concentrations using the Sonoclot analyzer.

METHODS

Ten milliliters of blood was collected from healthy adult dogs. Sonoclot tests were run in duplicate and included a control sample and five tPA concentrations: 50, 75, 100, 150, and 200 IU/mL of blood.

RESULTS

Eleven dogs were enrolled in the study. Based on standard Sonoclot Signature changes, a numeric value fibrinolysis time (FTi) was derived to aid in the quantification of hyperfibrinolysis. Activated clotting time and clot rate Sonoclot values were not significantly affected by any tPA concentration. There was a significant decrease in platelet function (PF) at tPA concentrations equal to and above 75 IU/mL on channel 1 and tPA concentrations of 150 IU/mL and higher on channel 2. There was a progressive decrease in FTi at increasing tPA concentrations.

CONCLUSIONS

The Sonoclot analyzer can be used to evaluate hyperfibrinolysis. Predictable changes were seen in the Sonoclot Signature and a decrease in PF and FTi was found with increasing tPA concentrations. The Sonoclot assay with a tPA concentration of 100 IU/mL is suggested a baseline measure of hyperfibrinolysis and has a resultant median FTi of 42 minutes, which is a practical time for clinical applications.

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.

The role of cryoprecipitate in human and canine transfusion medicine

OBJECTIVE

To evaluate the current role of cryoprecipitate in human and canine transfusion medicine.

DATA SOURCES

Human and veterinary scientific reviews and original studies found using PubMed and CAB Abstract search engines were reviewed.

HUMAN DATA SYNTHESIS

In the human critical care setting, cryoprecipitate is predominantly used for fibrinogen replenishment in bleeding patients with acute traumatic coagulopathy. Other coagulopathic patient cohorts for whom cryoprecipitate is recommended include those undergoing cardiovascular or obstetric procedures or patients bleeding from advanced liver disease. Preferential selection of cryoprecipitate versus fibrinogen concentrate (when available) is currently being investigated. Also a matter of ongoing debate is whether to administer this product as part of a fixed-dose massive hemorrhage protocol or to incorporate it into a goal-directed transfusion algorithm applied to the individual bleeding patient.

VETERINARY DATA SYNTHESIS

Although there are sporadic reports of the use of cryoprecipitate in dogs with heritable coagulopathies, there are few to no data pertaining to its use in acquired hypofibrinogenemic states. Low fibrinogen in dogs (as in people) has been documented with acute traumatic coagulopathy, advanced liver disease, and disseminated intravascular coagulation. Bleeding secondary to these hypocoagulable states may be amenable to cryoprecipitate therapy. Indications for preferential selection of cryoprecipitate (versus fresh frozen plasma) remain to be determined.

CONCLUSIONS

In the United States, cryoprecipitate remains the standard of care for fibrinogen replenishment in the bleeding human trauma patient. Its preferential selection for this purpose is the subject of several ongoing human clinical trials. Timely incorporation of cryoprecipitate into the transfusion protocol of the individual bleeding patient with hypofibrinogenemia may conserve blood products, mitigate adverse transfusion-related events, and improve patient outcomes. Cryoprecipitate is readily available, effective, and safe for use in dogs. The role of this blood product in clinical canine patients with acquired coagulopathy remains unknown.

Effects of storage time and temperature on thromboelastographic analysis in dogs and horses

BACKGROUND

The accessibility of thromboelastography (TEG) to general practitioners is limited by short sample storage times (30 minutes) and storage temperatures (20-23°C).

OBJECTIVES

We aimed to evaluate the stability of canine and equine citrated blood samples when stored for extended periods of time, both at room temperature (RT) (20-23°C) and refrigerator temperature (FT) (2-7.5°C).

METHODS

Citrated whole blood samples from healthy dogs and horses (n = 10 for each) were stored for 30 minutes (baseline) at RT before TEG analysis. Baseline values for TEG variables R, K, α, MA, LY30, and LY60 were compared with those from samples stored for 2, 8, and 22.5 h, at RT and FT. Results were compared using an ANOVA (P < .05). Total allowable analytical error (TE_a ) based on biological variation data was used to evaluate stability.

RESULTS

In dogs, statistically significant differences included shorter R, longer K, decreased MA, and increased LY60 at various time points and storage temperatures from 2 h onward. Only samples stored for 2 h at FT showed acceptable stability compared with TE_a . In horses, statistically significant differences included shorter R and K, and decreased α, LY30, and LY60 at various time points and storage temperatures from 2 h onward. Samples were not stable at any time compared with TE_a , regardless of the temperature.

CONCLUSIONS

In this study, canine samples could be stored for up to 2 h at FT without affecting TEG results; equine samples should be stored for 30 minutes at RT.

Establishment of normal reference intervals in dogs using a viscoelastic point-of-care coagulation monitor and its comparison with thromboelastography

BACKGROUND

Viscoelastic coagulation devices are a useful adjunct to the evaluation of hemostasis in veterinary patients. VCM Vet is a point-of-care device that is simple in operation and could be used to diagnose and trend hemostatic abnormalities in sick patients. VCM Vet does not use activators.

OBJECTIVES

We aimed to establish reference intervals (RIs) for VCM Vet in a healthy adult canine population and concurrently perform thromboelastographic (TEG) analysis on these samples with and without tissue factor (TF) activation for RI comparisons.

METHODS

Duplicate VCM Vet tests were performed immediately upon sample collection. Two concurrent TEG tests were performed on the remaining blood, one citrated, untreated (CU), and one activated with TF at a 1:3600 dilution.

RESULTS

Fifty-two dogs were enrolled in the study. The following RIs were generated for VCM Vet machine 1 and 2, respectively: clot time (CT) (seconds) 163-480 and 172-457; clot formation time (CFT) (seconds) 104-288 and 94-252, α-angle (degrees) 41-65 and 44-66, and maximum clot firmness (MCF) (no units) 27-43 and 30-46. Moderate to good correlations were observed between the two machines with Lin's concordance correlation coefficients of 0.51-0.9 and a P < 0.002. TEG RIs were similar to previously reported values.

CONCLUSIONS

VCM Vet RIs were generated. Each VCM Vet device should have a unique RI established due to inter-device variability. Direct correlations of VCM Vet values with TEG parameters were not performed due to the narrow range of the normal values and the need to evaluate patients with a wide range of hemostatic abnormalities.

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.

Prospective, controlled, blinded, randomized crossover trial evaluating the effect of maropitant versus ondansetron on inhibiting tranexamic acid-evoked emesis

OBJECTIVE

To evaluate the incidence of tranexamic acid (TXA)-induced nausea and vomiting after the prophylactic use of 2 antiemetics, ondansetron and maropitant, compared with saline.

DESIGN

Prospective, blinded, placebo-controlled, randomized, crossover study.

SETTING

University research facility.

ANIMALS

Eight adult, purpose-bred Beagles.

INTERVENTION

Dogs received 3 treatments on 3 occasions with a 3-week washout period. Either maropitant (1 mg/kg), ondansetron (0.2 mg/kg), or saline solution was given intravenously in equal volumes, followed 10 minutes later by 50 mg/kg IV TXA. A blinded observer evaluated the dogs for signs of vomiting and nausea for 30 minutes. The severity of nausea was assessed with a visual analog scale (VAS) and recorded at baseline before TXA, and at the end of 3 observational periods: 0-5, 5-15, and 15-30 minutes after TXA. A generalized linear mixed effect model was used to assess for group and period effects. Statistical significance was set at P < 0.05 .

MEASUREMENTS AND MAIN RESULTS

None of the dogs vomited after maropitant. Emesis occurred in 5 out of 8 dogs (62.5%), a median (range) of 1 time (1-2) after ondansetron and 1 time (1-3) after saline. There was a significant effect on vomiting of maropitant against saline (P < 0.0001) but not for ondansetron against saline (P = 0.53). The highest nausea VASs were recorded during the first 5 minutes after TXA with a significant reduction of VAS variability in the maropitant group (P = 0.003). The effect of maropitant and ondansetron against saline on the severity of nausea was not statistically significant (P = 0.069).

CONCLUSION

The neurokinin 1 receptor antagonist maropitant at the dose used, administered IV 10 minutes before 50 mg/kg TXA, was effective in preventing vomiting compared with ondansetron and placebo. Our results support the prophylactic IV administration of maropitant in dogs that are scheduled to receive TXA.

Prospective observational study of dogs with splenic mass rupture suggests potentially lower risk of malignancy and more favourable perioperative outcomes

Haemoperitoneum secondary to ruptured splenic tumours can be either benign or malignant in origin. The majority of previous studies of canine haemoperitoneum have been retrospective, which are associated with well-recognized biases, such as the potential to underappreciate the diversity of outcomes in a complex presentation such as haemoperitoneum. This study seeks to prospectively define perioperative morbidity and mortality of haemoperitoneum in dogs secondary to ruptured splenic masses. Forty dogs with haemoperitoneum secondary to a ruptured splenic mass met the inclusion criteria. As expected, the cohort predominately consisted of older large breed dogs. All dogs underwent preoperative staging and had a splenectomy performed. Histopathologic analysis was performed on the splenic mass, as well as any possible metastatic lesions that were noted intra-operatively. Perioperative care outside of splenectomy was delivered in specialty practices using current conventional approaches to care (eg, transfusions and anti-arrhythmic medications). Fifteen dogs (37.5%) had benign splenic tumours and were cured with surgery alone, whereas 62.5% had malignant disease (most often haemangiosarcoma [HSA]). Surgical outcomes were highly favourable in the vast majority of dogs. Indeed, 38 dogs (95%) survived and were discharged after a median hospitalization of 39.5 hours. Independent predictors of longer hospitalization times included receiving a transfusion and the development of an arrhythmia. Although small, this cohort defines distinctive and optimistic perspectives for dogs with haemoperitoneum from splenic tumour rupture. These favourable outcomes from this prospective study are sufficient to ask if larger prospective studies should be conducted to better inform owners during this challenging cancer emergency presentation.

A Novel Microchip Flow Chamber (Total Thrombus Analysis System) to Assess Canine Hemostasis

Hemorrhagic diseases are common in dogs. Current coagulation assays do not model all aspects of in vivo hemostasis and may not predict bleeding risk. The Total-Thrombus Analysis System (T-TAS) is a novel hemostasis assay system in which whole blood flows through microfluidic channels at defined shear rates to provide qualitative and quantitative evaluation of platelet function (PL-chip) and coagulation function (AR-chip). The present study evaluated the T-TAS in dogs with hereditary bleeding disorders and with acquired hemorrhagic syndromes (Group 1), and healthy controls (Group 2). Hereditary defects included von Willebrand's disease (VWD; n = 4), hemophilia A (n = 2), and canine Scott syndrome (n = 2). Acquired hemorrhagic disorders included neoplastic hemoperitoneum (n = 2) and acute hemorrhagic diarrhea syndrome (n = 1). Citrate anticoagulated samples were collected from diseased dogs (Group 1, n = 11) and controls (Group 2, n = 11) for coagulation screening tests, fibrinogen analyses, D-dimer concentration, antithrombin activity, von Willebrand Factor antigen, PFA-100 closure time (PFA-CT), and thromboelastography (TEG). Citrate and hirudin anticoagulated samples were used for T-TAS analyses at two shear rates. Qualitative thrombus formation in each chip was recorded using the T-TAS video camera. Numeric parameters, derived from the instrument software, included occlusion start time (OST; time to 10 kPa), occlusion time (OT; time to 60 kPa (PL-chip) or 80 kPa (AR-chip)), and area under the pressure curve (AUC). Correlations between continuous variables were evaluated by Spearman's rank. Continuous variables were compared between groups by Student's t-test or the Mann-Whitney U-test. Alpha was set at 0.05. In combined analyses of all dogs, significant correlations were identified between T-TAS variables, between the PFA-CT and PL-chip parameters and between TEG variables and AR-chip parameters. The prothrombin time correlated with the AR-chip AUC at both shear rates. In Group 1 dogs, the AR-chip AUC at low shear was significantly reduced compared with Group 2 dogs. Aberrant thrombus formation was seen in video images recorded from dogs with VWD and hemophilia A. The T-TAS AR-chip analysis distinguished dogs with bleeding risk compared to healthy controls. Initial evaluations of the T-TAS suggest it may aid characterization of hemostasis in patients at-risk of bleeding and assist with delineating bleeding phenotypes.

Reference Intervals for and the Effects of Sample Handling and Sex on Rotational Thromboelastometry in Healthy Adult Pigs

Accurate assessment of coagulation in porcine studies is essential. We sought to establish normal values for porcine rotational thromboelastometry (ROTEM) according to the American Society for Veterinary Clinical Pathology guidelines and to assess the effects of various preanalytical parameters on those measurements. Healthy Yorkshire-cross pigs (n = 81; 46 males and 35 females) were anesthetized. By using a 18-gauge needle attached to a vacuum phlebotomy tube, blood was acquired from the cranial vena cava. Tubes were filled in the following order: evacuation clot tube, EDTA tube, heparin tube, and 2 citrate tubes. The citrate tubes were randomly assigned to 30 min with or without constant agitation on a rocker. The following parameters were reported according to the manufacturer's recommendations: clotting time, clot formation time, α, (tangent to the clot formation curve when the clot firmness is 20 mm), clot firmness after 10 and 20 min, maximal clot firmness, maximum lysis, and lysis indexes at 30 and 45 min. Reference intervals were reported as mean ± 2 SD (parametric distribution) or 2.5th and 97.5th percentile of the population's results (nonparametric distribution). The effects of sex, sampling order, and agitation on ROTEM results were analyzed through linear regression. Neither sex nor sample agitation influenced any of the ROTEM parameters. Combined reference intervals were established for each ROTEM parameter by pooling data from the nonagitated tubes for both male and female pigs. This study is the first to establish ROTEM reference intervals from a large number of male and female adult Yorkshire-cross pigs and to provide a detailed description of preanalytical sample processing.

Enhanced fibrinolysis detection in a natural occurring canine model with intracavitary effusions: Comparison and degree of agreement between thromboelastometry and FDPs, D-dimer and fibrinogen concentrations

Dogs with intracavitary effusion have coagulative abnormalities indicative of primary fibrinolysis/hyperfibrinolysis. The aim of this case control study was to investigate by rotational thromboelastometry (ROTEM) and standard coagulation tests (fibrin-fibrinogen degradation products, D-dimer and fibrinogen) fibrinolysis in dogs with intracavitary effusions. Thirty-two dogs with intracavitary effusion and 32 control sick dogs without effusion were studied. Frequency of fibrinolysis grade of severity (i.e., hypofibrinolysis/basal fibrinolysis vs increased fibrinolysis vs hyperfibrinolysis) by ROTEM and standard coagulation tests were compared between groups. Pattern of fibrinolysis by ROTEM (i.e., late vs intermediate vs fulminant) and type of fibrinolysis by standard coagulation tests (i.e., hypofibrinolysis/basal fibrinolysis vs primary fibrinolysis vs secondary fibrinolysis vs primary hyperfibrinolysis vs secondary hyperfibrinolysis) were also compared between groups. Dogs with intracavitary effusion had a lesser degree of hypofibrinolysis and basal fibrinolysis and a higher degree of increased fibrinolysis and hyperfibrinolysis compared to controls, both by ROTEM and by standard coagulation tests (P = 0.042 and P = 0.017, respectively). Nevertheless, there was a poor agreement between the two classification schemes (34.4%, K = 0.06, 95% CI = -0.14 ‒ +0.26). Dogs with intracavitary effusion showed, by ROTEM, a lesser degree of hypofibrinolysis and basal fibrinolysis and a higher degree of late, intermediate, and fulminant fibrinolysis compared to controls (P = 0.044). Finally, dogs with intracavitary effusion had, by standard coagulation tests, a higher frequency of primary fibrinolysis and primary hyperfibrinolysis and a lower frequency of secondary fibrinolysis compared to controls. Dogs with intracavitary effusion showed an increased frequency and a different and more severe pattern of fibrinolysis compared to controls.

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point-of-care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point-of-care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed.

Temporary abdominal packing for management of persistent hemorrhage after liver lobectomy in three dogs with hepatic neoplasia

OBJECTIVE

To describe the technique and outcome of temporary abdominal packing for control of persistent hemorrhage from liver lobectomy sites in 3 dogs with hepatic neoplasia.

SERIES SUMMARY

Three dogs were treated with massive transfusion for hemoperitoneum secondary to bleeding hepatic tumors. Surgical resection of the affected liver lobe(s) was performed but hemostasis could not be achieved through conventional methods. All 3 dogs demonstrated acidosis, hypothermia, and coagulopathy. Temporary abdominal packing of liver lobectomy sites was performed and hemostasis was achieved in all dogs. One dog died prior to removal of the packing. The other 2 dogs had the packing removed with no evidence of rebleeding. One dog was euthanized after removal of the packing due to acute kidney injury and the remaining dog survived to discharge.

NEW OR UNIQUE INFORMATION PROVIDED

Temporary abdominal packing combined with medical management was successful in achieving hemostasis in all 3 dogs, however, 2 dogs died of complications related to multiple organ dysfunction syndrome. Temporary abdominal packing may be considered when definitive surgical hemostasis cannot be achieved or in unstable patients not able to tolerate prolonged surgical times. Further research is needed to better define efficacy, optimal patient selection, packing technique, timing of removal, and complications associated with temporary abdominal packing.

Pharmacokinetics of tranexamic acid in healthy dogs and assessment of its antifibrinolytic properties in canine blood

OBJECTIVE To assess pharmacokinetics of tranexamic acid (TXA) in dogs and assess antifibrinolytic properties of TXA in canine blood by use of a thromboelastography-based in vitro model of hyperfibrinolysis. ANIMALS 6 healthy adult dogs. PROCEDURES Dogs received each of 4 TXA treatments (10 mg/kg, IV; 20 mg/kg, IV; approx 15 mg/kg, PO; and approx 20 mg/kg, PO) in a randomized crossover-design study. Blood samples were collected at baseline (time 0; immediately prior to drug administration) and predetermined time points afterward for pharmacokinetic analysis and pharmacodynamic (thromboelastography) analysis by use of an in vitro hyperfibrinolysis model. RESULTS Maximum amplitude (MA [representing maximum clot strength]) significantly increased from baseline at all time points for all treatments. The MA was lower at 360 minutes for the 10-mg/kg IV treatment than for other treatments. Percentage of clot lysis 30 minutes after MA was detected was significantly decreased from baseline at all time points for all treatments; at 360 minutes, this value was higher for the 10-mg/kg IV treatment than for other treatments and higher for the 20-mg/kg IV treatment than for the 20-mg/kg PO treatment. Maximum plasma TXA concentrations were dose dependent. At 20 mg/kg, IV, plasma TXA concentrations briefly exceeded concentrations suggested for complete inhibition of fibrinolysis. Oral drug administration resulted in a later peak antifibrinolytic effect than did IV administration. CONCLUSIONS AND CLINICAL RELEVANCE Administration of TXA improved clot strength and decreased fibrinolysis in blood samples from healthy dogs in an in vitro hyperfibrinolysis model. Further research is needed to determine clinical effects of TXA in dogs with hyperfibrinolysis.

Hypocoagulability and Platelet Dysfunction Are Exacerbated by Synthetic Colloids in a Canine Hemorrhagic Shock Model

Background: Hemorrhagic shock and volume replacement can alter coagulation. Synthetic colloids, hydroxyethyl starch (HES), and gelatin, may enhance hypocoagulability. Our primary objective was to describe the effect of four fluid products on coagulation in canine hemorrhagic shock. Our secondary objective was to compare measurements of coagulation during shock to baseline in all dogs.

Methods: Anesthetized greyhounds subjected to atraumatic hemorrhage for 60 min were administered 20 mL kg⁻¹ of either fresh whole blood (FWB), 6% HES 130/0.4, 4% succinylated gelatin (GELO), or 80 mL kg⁻¹ of isotonic crystalloid over 20 min (n = 6 per group). Platelet closure time (PCT), rotational thromboelastometry (ROTEM) and plasma coagulation assays were measured at baseline, end of hemorrhage (shock), and 40 (T60), and 160 (T180) min after study fluid. ROTEM parameters included clotting time (CT), clot formation time (CFT), alpha angle, maximum clot firmness (MCF), lysis index at 60 min (LI60), and thrombodynamic potential index (TPI) for INTEM, EXTEM, FIBTEM (MCF only), and APTEM (LI60 only) profiles. Plasma coagulation assays included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen concentration and activities of factor VII (FVII), factor VIII (FVIII), and von Willebrand Factor antigen (vWF). Between-group differences were tested using linear mixed models with post-hoc between-group comparisons (Bonferroni-Holm corrected). Differences between baseline and shock were tested using paired t-tests. Significance was set at P < 0.05.

Results: GELO showed longer PCT at T60, compared with FWB and CRYST, and at T180, compared with all other groups. HES showed longer EXTEM CT at T60, compared with all other groups. HES showed lower INTEM and EXTEM MCF at T60 and lower INTEM MCF at T180, compared with FWB. Some plasma coagulation assays showed greater hypocoagulability with HES. Comparing shock to baseline, EXTEM CT, INTEM CFT, EXTEM CFT, PT, and FVIII significantly increased and PCT, INTEM CT, INTEM MCF, EXTEM MCF, EXTEM LI60, EXTEM TPI, FIBTEM MCF, APTT, fibrinogen, FVII, and vWF significantly decreased.

Conclusions: In dogs with hemorrhagic shock, volume replacement with GELO caused mild platelet dysfunction and HES was associated with coagulation changes consistent with hypocoagulability, beyond effects of hemodilution. Shock alone produced some evidence of hypocoagulability.

Characteristics of hyperfibrinolysis in dogs and cats demonstrated by rotational thromboelastometry (ROTEM)

Hyperfibrinolysis (HFL) is a pathophysiological mechanism that has not been described in dogs or cats extensively. The aim of this study was to describe rotational thromboelastometry (ROTEM) parameters and underlying diagnosis in dogs and cats with HFL and evaluate association with bleeding diathesis. The ROTEM database was retrospectively searched for EXTEM (ROTEM activated with proprietary tissue factor) tracings with maximum lysis at 60min ≥15%. Concurrent ROTEM and plasma coagulation tests, thrombocyte number, diagnosis and survival to hospital discharge were extracted from medical records. Analysis of differences between dogs and cats and of factors associated with bleeding, fulminant HFL (clot breakdown within 30min) and survival to hospital discharge were performed. Hyperfibrinolysis was detected in eight cats presenting with haemoabdomen or haemothorax (n=4/8, 50%) and trauma (n=3/8, 38%) and in 36 dogs with angiostrongylosis (n=12, 33%), neoplasia (n=7, 19%), liver disease (n=4, 11%) and others including apparently healthy dogs (n=3, 8%). Hyperfibrinolysis was associated with prolonged EXTEM and APTEM (EXTEM with added apoprotein for inhibition of HFL) clotting time and decreased FIBTEM (EXTEM with added cytochalasin D for inhibition of thrombocytes) maximum clot firmness (MCF) in dogs and cats and with decreased EXTEM MCF in dogs. Bleeding dogs had significantly hypocoagulable EXTEM tracings. Fulminant HFL was associated with severe hypofibrinogenaemia in dogs (P=0.005) and was not associated with survival to hospital discharge. Evidence of HFL was demonstrated in dogs and cats with bleeding, trauma, parasitic and neoplastic disease. HFL is associated with late and weak clot formation.

Retrospective comparison of standard clotting tests and novel clot waveform parameters in dogs using the turbidimetric ACL-TOP CTS 300 coagulation analyzer

Clot waveforms are generated by coagulation analyzers, such as the ACL-TOP, that utilize photo-optical turbidimetric methods to measure prothrombin time (PT) and activated partial thromboplastin time (aPTT), which are standard clotting tests (SCTs). Additional quantitative clot waveform analysis (CWA) parameters include maximum velocity of the PT curve (PT1d), maximum acceleration of the aPTT curve (aPTT2d), and their change in optical density (ODdelta). We explored the potential for CWA to contribute unique information compared to SCTs and quantitative fibrinogen assay (QFA) in dogs with clinical indications for laboratory evaluation of coagulation. We retrospectively evaluated the frequency and agreement between normal, high, and low values of CWA and SCTs for 203 dogs relative to reference intervals (RIs). Most dogs had SCTs within RIs, but most CWA values were high regardless of whether SCT values were within, below, or above the RI. Agreement between SCTs and CWA was slight (kappa <30%). Clinically significant bleeding was noted in 28 of 203 (14%) dogs. SCTs were not different between bleeders and non-bleeders. Median QFA, PT1d, aPTTdelta, and aPTT2d values were statistically significantly higher than RIs in non-bleeders compared to bleeders, whose median values were not below RI. Compared with SCTs, CWA identified differences between the 2 groups. However, wide overlap between the 2 groups limits the use of CWA to clinically discriminate between bleeders and non-bleeders in a heterogeneous population of dogs. Further studies on the diagnostic utility of CWA in coagulopathic dogs are needed.

Spontaneous hemoperitoneum and anaphylactic shock associated with Hymenoptera envenomation in a dog

OBJECTIVE

To describe the clinical presentation of a dog with spontaneous hemoperitoneum associated with anaphylactic shock from Hymenoptera envenomation.

CASE SUMMARY

An 8-year-old female neutered Beagle presented as an emergency for acute onset of collapse, hematemesis, and hematochezia. The dog was tachycardic, tachypneic, and hypotensive. Initial assessment revealed a hemoperitoneum with documentation of a nonclotting sanguineous peritoneal effusion with PCV 81% and total protein concentration 65 g/L (6.5 g/dL). No obvious masses were appreciated ultrasonographically during original presentation and cytology of the peritoneal effusion was unremarkable. Peripheral PCV was 67% and total plasma protein concentration was 72 g/L (7.2 g/dL). A bee stinger was located in the right upper lip after presentation and was postulated to be the inciting trigger for the abdominal hemorrhage and shock. The patient was medically stabilized and ultimately made an uneventful recovery. Abdominal ultrasound performed 3 days after discharge revealed a single 0.85 cm hyperechoic liver nodule. Follow-up evaluation at 6 and 18 months after presentation documented a normal physical examination, unremarkable thoracic radiographs, and no change in the original hyperechoic liver nodule.

NEW OR UNIQUE INFORMATION PROVIDED

This report details an unusual clinical presentation of anaphylactic shock due to Hymenoptera envenomation in a dog. To the authors' knowledge, spontaneous hemoperitoneum associated with anaphylaxis and bee envenomation has not been documented in the veterinary literature.

Plasmatic coagulation and fibrinolysis in healthy and Otostrongylus-affected Northern elephant seals (Mirounga angustirostris)

BACKGROUND

Prepatent Otostrongylus arteritis results in hemorrhagic diathesis in free-ranging Northern elephant seals (Mirounga angustirostris) attributed to aberrant larval migration of the lungworm, Otostrongylus circumlitus. Clinical signs are often nonspecific, including lethargy, anorexia, and blepharospasm, but can progress to spontaneous frank hemorrhage and death within 72 hours of onset. Previously published case reports describe coagulopathy with prolonged PT and APTT, normal to elevated platelet counts, normal antithrombin concentrations, and low concentrations of fibrinogen degradation products. Disseminated intravascular coagulation was proposed as the cause of hemorrhage, but is inconsistent with some of the reported clinicopathologic changes.

OBJECTIVE

The purpose of this study was to compare plasmatic coagulation and fibrinolysis in healthy and Otostrongylus-affected elephant seals, in order to identify potential therapy. We hypothesized that hyperfibrinolysis contributed to hemorrhage in these cases.

METHODS

Citrated plasma samples were collected from 3- to 4-month-old Northern elephant seals in a wildlife rehabilitation hospital. The sampled population included 25 healthy, prerelease seals and 32 clinically ill seals diagnosed with presumptive Otostrongylus arteritis. Twenty-one of the included seals had Otostrongylus infestation confirmed at necropsy. Standard coagulation tests and plasma thromboelastography were performed for a complete assessment of coagulation and fibrinolysis.

RESULTS

Northern elephant seals with definitive Otostrongylus infestation were hypocoagulable and hypofibrinolytic compared to healthy controls.

CONCLUSIONS

Results were most consistent with disseminated intravascular coagulation. Treatment with antifibrinolytic drugs to control hemorrhage may be unrewarding; alternative therapies such as plasma transfusions or coagulation factor concentrates should be investigated.

Hyperfibrinolysis and Hypofibrinogenemia Diagnosed With Rotational Thromboelastometry in Dogs Naturally Infected With Angiostrongylus vasorum

Background

The pathomechanism of Angiostrongylus vasorum infection‐associated bleeding diathesis in dogs is not fully understood.

Objective

To describe rotational thromboelastometry (ROTEM) parameters in dogs naturally infected with A. vasorum and to compare ROTEM parameters between infected dogs with and without clinical signs of bleeding.

Animals

A total of 21 dogs presented between 2013 and 2016.

Methods

Dogs with A. vasorum infection and ROTEM evaluation were retrospectively identified. Thrombocyte counts, ROTEM parameters, clinical signs of bleeding, therapy, and survival to discharge were retrospectively retrieved from patient records and compared between dogs with and without clinical signs of bleeding.

Results

Evaluation by ROTEM showed hyperfibrinolysis in 8 of 12 (67%; 95% CI, 40–86%) dogs with and 1 of 9 (11%; 95% CI, 2–44%) dogs without clinical signs of bleeding (P = .016). Hyperfibrinolysis was associated with severe hypofibrinogenemia in 6 of 10 (60%; 95% CI, 31–83%) of the cases. Hyperfibrinolysis decreased or resolved after treatment with 10–80 mg/kg tranexamic acid. Fresh frozen plasma (range, 14–60 mL/kg) normalized follow‐up fibrinogen function ROTEM (FIBTEM) maximal clot firmness in 6 of 8 dogs (75%; 95% CI, 41–93%). Survival to discharge was 67% (14/21 dogs; 95% CI, 46–83%) and was not different between dogs with and without clinical signs of bleeding (P = .379).

Conclusion and Clinical Importance

Hyperfibrinolysis and hypofibrinogenemia were identified as an important pathomechanism in angiostrongylosis‐associated bleeding in dogs. Hyperfibrinolysis and hypofibrinogenemia were normalized by treatment with tranexamic acid and plasma transfusions, respectively.

Thromboelastography in Dogs with Chronic Hepatopathies

BACKGROUND

The coagulation status of dogs with liver disease is difficult to predict using conventional coagulation testing.

HYPOTHESIS/OBJECTIVES

To evaluate thromboelastography (TEG) results and associations with conventional coagulation results and indicators of disease severity and prognosis in dogs with chronic hepatopathies (CH).

ANIMALS

Twenty-one client-owned dogs.

METHODS

Dogs with CH were prospectively (10 dogs) and retrospectively (11 dogs) enrolled from 2008 to 2014. Kaolin-activated TEG was performed and compared with reference intervals by t-tests or Mann-Whitney tests. Correlation coefficients for TEG results and conventional coagulation and clinicopathologic results were determined. Significance was set at P < .05.

RESULTS

Dogs with CH had significant increases in R (5.30 min vs 4.33 min), K (3.77 min vs 2.11 min), and LY30 (4.77% vs 0.68%) and decreased angles (55.3° vs 62.4°). G value defined 9 of 21, 7 of 21, and 5 of 21 dogs as normocoagulable, hypercoagulable, and hypocoagulable, respectively. G and MA were correlated with fibrinogen (r = 0.68, 0.83), prothrombin time (PT; r = -0.51, -0.53), and activated partial thromboplastin time (aPTT; r = -0.50, -0.50). K was correlated with PT (r = 0.75) and protein C activity (r = -0.92). Angle was correlated with aPTT (r = -0.63). Clinical score was correlated with PT (r = 0.60), MA (r = -0.53), and R (r = -0.47). Dogs with hyperfibrinolysis (LY30 > 3.04%; 5 of 21) had significantly higher serum transaminase activities. Dogs with portal hypertension had significantly lower G, MA, and angle and prolonged, K, R, and PT.

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs with CH have variable TEG results. Negative prognostic indicators in CH correlate with hypocoagulable parameters on TEG. Hyperfibrinolysis in dogs with CH is associated with high disease activity.

Hemorrhagic, Hemostatic, and Thromboelastometric Disorders in 35 Dogs with a Clinical Diagnosis of Leptospirosis: A Prospective Study

Background

Leptospirosis in dogs is occasionally associated with a hemorrhagic syndrome, the pathophysiology of which is not fully understood.

Hypothesis/Objectives

To characterize hematologic, hemostatic, and thromboelastometric abnormalities in dogs with leptospirosis and to study their association with hemorrhagic diatheses and outcomes.

Animals

Thirty‐five client‐owned dogs.

Methods

A prospective observational single cohort study was conducted. Results from the CBC, coagulation tests (prothrombin, activated partial thromboplastin and thrombin times, fibrinogen, fibrin(ogen) degradation products, and D‐dimer concentrations), rotational thromboelastometry (TEM), signalment, hemorrhagic diatheses, occurrence of disseminated intravascular coagulation (DIC) at admission, and survival to discharge were recorded.

Results

The most common hematologic and hemostatic abnormalities were anemia (30/35), thrombocytopenia (21/35), and hyperfibrinogenemia (15/35). Eight dogs were diagnosed with DIC. A normal TEM profile was found in 14 dogs, a hypercoagulable profile in 14 dogs, and a hypocoagulable profile in 7 dogs. The 8 dogs with hemorrhagic diatheses at admission had significantly decreased platelet counts (P = .037) and increased D‐dimer concentrations (P = .015) compared with other dogs. Dogs with a hypocoagulable profile exhibited more hemorrhagic diatheses compared with the dogs that had normal and hypercoagulable profiles (P = .049). The mortality rate was lower in dogs with a hypercoagulable profile than in those with a hypocoagulable profile (21% vs 57%; P = .043). Disseminated intravascular coagulation was not a significant prognostic factor.

Conclusions and Clinical Importance

Thromboelastometric parameters were altered in dogs with both hypercoagulable and hypocoagulable profiles. A hypocoagulable profile was significantly correlated with hemorrhagic diathesis and higher mortality rate.

Point of Care Assessment of Coagulation

Disorders of hemostasis can be difficult to fully elucidate but can severely affect patient outcome. The optimal therapy for coagulopathies is also not always clear. Point of care (POC) testing in veterinary medicine can assist in the diagnosis of hemostatic disorders and also direct treatment. Advantages of POC testing include rapid turnaround times, ease of use, and proximity to the patient. Disadvantages include differences in analytic performance compared with reference laboratory devices, the potential for operator error, and limited test options per device. Conventional coagulation tests such as prothrombin time, activated partial thromboplastin time, and activated clotting time can be measured by POC devices and can accurately diagnose hypocoagulability, but they cannot detect hypercoagulability or disorders of fibrinolysis. Viscoelastic POC coagulation testing more accurately evaluates in vivo coagulation, and can detect hypocoagulability, hypercoagulability, and alterations in fibrinolysis. POC platelet function testing methodologies can detect platelet adhesion abnormalities including von Willebrand disease, and can be used to monitor the efficacy of antiplatelet drugs. It is unlikely that a single test would be ideal for assessing the complete coagulation status of all patients; therefore, the ideal combination of tests for a specific patient needs to be determined based on an understanding of the underlying disease, and protocols must be standardized to minimize interoperator and interinstitutional variability.