Hemostatic Disorders Associated with Hepatobiliary Disease.

The liver plays a crucial role in all aspects of coagulation because most factors that regulate procoagulation, anticoagulation, and fibrinolysis are produced, cleared, and/or activated in the liver. Establishing the coagulation status of an individual patient with hepatobiliary disease can therefore be challenging. Although, classically, patients with hepatobiliary disease were thought of as potentially hypocoagulable, hypercoagulability also occurs. The article summarizes the breadth of coagulation abnormalities that have been reported in dogs and cats with hepatobiliary disease and provides strategies to respond to bleeding and thrombotic risk.

Thromboelastometric evaluation of horses submitted to experimental thrombosis and jugular thrombectomy / Avaliação tromboelastométrica de equinos submetidos a trombose e trombectomia jugular experimental

Jugular thrombosis in horses occurs commonly in iatrogenic situations, secondary to endotoxemic clinical condition and disseminated vascular coagulation, potentially leading to death. Thus, hemostatic evaluation becomes necessary and extremely important for monitoring the risks of systemic hypercoagulability and for the efficiency of allopathic and surgical treatment. This paper describes the hemostatic behavior in experimental jugular thrombosis of ten healthy equines, subsequently submitted to two thrombectomy techniques and receiving heparin sodium as anti-rethrombosis therapy. These animals were evaluated for 20 days by thromboelastometry (TEM), platelet count, hematocrit and fibrinogen, at four moments: pre-induction to phlebitis (D0-MPF); three days after thrombophlebitis induction (D3-MFM); 6 days after, - moment of thrombophlebitis - (D9-MT); and 54 (D16) and 126 (D19) hours after thrombectomies (PTM). Thrombectomy was performed via a Vollmar Ring (group 1, n=5) and Fogarty catheter (group 2, n=5). All the animals received heparin (150 UI/kg, SC) every 12 hours, for ten days after the respective thrombectomies. Through the blood samples were evaluated TEM, activated partial thromboplastin time (aPTT) and prothrombin time (PT), dosing of fibrinogen, hematocrit and platelet count at the abovementioned moments. For comparison between groups and moments the t test was applied at 5% significance level. No significant difference was verified between treatment groups at any of the moments. There were reductions in clotting time (CT) and clot formation time (CFT), with increase in maximum lysis (ML) until the moment D9-MT. Evaluation through INTEM® reagent presented prolongations of CT and CFT with reduction of α angle and ML starting from D16 and D19. Similarly, aPTT presented significant differences between moments pre- (D0, 3 and 9) and post- (D16 and 19) anticoagulant and surgical treatment. The platelet numbers were diminished at moments D16 and D19. In evaluation with EXTEM® reagent, prolongation of CT and CFT occurred only between the moments D0 vs. D3 and vs. D9. O PT did not present significant differences. The results obtained demonstrate that experimental jugular thrombophlebitis leads to local clinical alterations, with impairment of tissue and of the extrinsic coagulation pathway (EXTEM® ), but without evidence of systemic hypercoagulability status, since there was no increase of the alpha angle or maximum clot firmness (MCF). Furthermore, TEM was shown useful and more sensitive than conventional coagulation tests (PT, aPTT and fibrinogen) for the monitoring of anticoagulant therapy, as demonstrated in other works.(AU)

A trombose jugular nos equinos ocorre comumente em situações iatrogênicas, secundárias a quadros endotoxêmicos e a coagulação vascular disseminada, podendo levar ao óbito. Por isso, avaliação hemostática se faz necessária e de extrema importância para monitorar os riscos de hipercoagulabilidade sistêmica e também a eficiência do tratamento alopático e cirúrgico. Este trabalho descreve o comportamento hemostático na trombose jugular experimental de dez equinos hígidos, submetidos posteriormente a duas técnicas de trombectomia e recebendo heparina sódica como terapia anti retrombosante. Estes animais foram avaliados durante 20 dias por tromboelastometria (TEM), contagem de plaquetas, hematócrito e fibrinogênio, em quatro momentos: pré-indução à flebite (D0-MPF); três dias após a indução da tromboflebite (D3-MFM); 6 dias após, - momento de tromboflebite - (D9-MT); e 54 (D16) e 126 (D19) horas após as trombectomias (MPT). A trombectomia foi realizada com Anel de Vollmar (grupo 1, n=5) e cateter de Fogarty (grupo 2, n=5). Todos os animais receberam heparina (150 UI/Kg, SC) a cada 12 horas, durante dez dias após as respectivas trombectomias. Através de amostras de sangue, foram avaliadas a TEM, o tempo de tromboplastia parcial ativada (TTPa) e tempo de protrombina (TP), a dosagem de fibrinogênio, hematócrito e contagem de plaquetas nos momentos descritos acima. Para a comparação entre os grupos e momentos foi aplicado teste t, com nível de significância de 5%. Não foi verificada diferença significativa entre os grupos de tratamento em nenhum dos momentos. Houve redução do tempo de coagulação (CT) e do tempo de formação do coágulo (CFT), com aumento da lise máxima (LM) até o momento D9-MT. A avaliação com o reagente intem apresentou prolongamento do CT e do CFT e redução do ângulo α e da LM a partir do D16 e D19. Da mesma forma, o TTPa apresentou diferenças significativas entre os momentos pré (D0, 3 e 9) e pós (D16 e 19) tratamento cirúrgico e anticoagulante. Houve diminuição do número de plaquetas nos momentos D16 e D19. Na avaliação com reagente extem ocorreu apenas o prolongamento do CT e CFT entre os momentos D0 e o D3 e D9. O TP não apresentou diferenças significativas. Os resultados obtidos demonstram que a tromboflebite jugular experimental leva a alterações clínicas locais, com comprometimento tecidual e da via extrínseca da coagulação (extem), porém sem evidências de um estado sistêmico de hipercoagulabilidade, pois não houve aumento do ângulo alfa e da firmeza máxima do coágulo (MCF). Além disso, a TEM se mostrou útil e mais sensível que os testes convencionais de coagulação (TP, TTPa e fibrinogênio) para o acompanhamento da terapia anticoagulante, conforme demonstrado em outros trabalhos.(AU)

Haemostatic alterations in a group of canine cancer patients are associated with cancer type and disease progression.

BACKGROUND: Haemostatic alterations are commonly detected in human and canine cancer patients. Previous studies have described haemostatic dysfunction in canine patients with haemangiosarcomas and carcinomas, and haemostasis has been assessed in dogs with various malignant and benign neoplasias. Few studies have addressed the effect of cancer type and progression of disease on the presence of haemostatic alterations in canine patients. The objective of the present study was to evaluate haemostatic variables of coagulation and fibrinolysis in a group of canine cancer patients, and to compare haemostatic changes to the cancer type and progression of disease. METHODS: The study population consisted of 71 dogs with malignant neoplasia presented to the University Hospital for Companion Animals, Faculty of Life Sciences, University of Copenhagen, Denmark. The study was designed as a prospective observational study evaluating the haemostatic function in canine cancer patients stratified according to type of cancer disease and disease progression. The coagulation response was evaluated by thromboelastrography (TEG), platelet count, activated partial thromboplastin time (aPTT), prothombin time (PT), fibrinogen and antithrombin (AT); and fibrinolysis by d-dimer and plasminogen. RESULTS: Hypercoagulability was the most common haemostatic dysfunction found. Non mammary carcinomas had increased clot strength (TEG G), aPTT and fibrinogen compared to the other groups. When stratifying the patients according to disease progression dogs with distant metastatic disease exhibited significantly increased fibrinogen, and d-dimer compared to dogs with local invasive and local non-invasive cancers. CONCLUSION: Hypercoagulability was confirmed as the most common haemostatic abnormality in canine cancer patients and haemostatic dysfunction in canine cancer patients was found related to the cancer type and progression of disease. Increase in TEG G, aPTT and fibrinogen were observed in non-mammary carcinomas and were speculated to overall represent a proinflammatory response associated with the disease. Dogs with distant metastatic disease exhibited increased fibrinogen and d-dimer. Future studies are needed to elucidate the clinical importance of these results.

Haemostatic abnormalities in cats with naturally occurring liver diseases.

Alterations in the haemostatic system were characterized in cats with different naturally occurring liver diseases. The study looked at 44 healthy cats and 45 cats with different liver diseases confirmed histologically or cytologically (neoplasia, n=9; inflammation, n=12; hepatic lipidosis, n=13; other degenerative liver diseases, n=11). The following parameters were evaluated: platelet count; prothrombin time; activated partial thromboplastin time; thrombin time; factor (F) II, FV, FVII, FX, and FXIII activities; fibrinogen concentration; activities of antithrombin, protein C, plasminogen, and α(2)-plasmin inhibitor, and D-dimer concentration. In cats with liver diseases, 44/45 (98%) had one or more abnormalities of the coagulation parameters measured. In cats with inflammatory liver diseases, increased D-dimer concentrations and decreased FXIII activity were the most consistent abnormalities and were found in 83% and 75% of cats, respectively. The most common abnormality in cats with neoplastic liver disease was FXIII deficiency (78%). The most consistent abnormalities in cats with hepatic lipidosis were increased FV activity and D-dimer concentration with 54% of cats having values above the reference range for both parameters. Cats with miscellaneous degenerative liver disease most frequently showed FXIII deficiency (64%). The results of this study show that alterations of single haemostatic components are a frequent finding in cats with liver disease. Activation of haemostasis with subsequent consumptive coagulopathy (rather than decreased synthesis) seems to be responsible for these alterations. Increased blood levels of different haemostatic components in cats with inflammatory lesions may be related to an acute phase reaction.

Hemostatic abnormalities in dogs with carcinoma: a thromboelastographic characterization of hypercoagulability.

Hemostatic abnormalities were investigated in 32 dogs with carcinoma and 19 age-matched healthy dogs. Thromboelastography, hemostasis profile (i.e. prothrombin time [PT], activated partial thromboplastin time [aPTT], fibrinogen concentration), platelet count (PLT), thrombin-antithrombin complexes (TAT), and plasminogen activator inhibitor-1 (PAI-1) activity were evaluated. Dogs with carcinomas had faster thrombus generation (TEG(TG), a mathematic value obtained from the first derivate of the thromboelastographic tracing; 834.8±91.1 vs. 707.8±75.8mm/min; mean±SD), increased fibrinogen concentration (276 vs. 151mg/dL), and PLT (425 vs. 324U×10(9)/L), but had decreased PAI-1 activity (15.7 vs. 26.2IU/mL).The most common hemostatic abnormalities found in carcinoma dogs were hypercoagulability (TEG(TG)>mean+2 SD of healthy dogs) and thrombocytosis (PLT>424×10(9)U/L) in 46% of cases, and hyperfibrinogenemia (fibrinogen >384mg/dL) in 32% of cases. Disseminated intravascular coagulation was uncommon and the extent of disease was not correlated with hypercoagulability. TEG(TG) showed good correlation with fibrinogen (r=0.80) and hyperfibrinogenemia seems to be a main factor of the hypercoagulable state in carcinoma dogs. In conclusion, TEG(TG) is a valid parameter to diagnose hypercoagulability.

Monitoring unfractionated heparin therapy in dogs by measuring thrombin generation.

BACKGROUND: The calibrated automated thrombogram (CAT), an assay that permits measurement of thrombin generation in plasma, may be useful in studying hemostatic disorders and anticoagulant therapy in animals. OBJECTIVES: The aims of the study were to measure thrombin generation in healthy Beagle dogs and to evaluate the potential use of the CAT assay for monitoring therapy with unfractionated heparin (UFH). METHODS: Individual platelet-poor plasma samples and a plasma pool from 20 healthy adult Beagles were prepared. Serial UFH plasma dilutions were used to establish an in vitro heparin-sensitivity curve. The pharmacodynamic effects of heparin in vivo were evaluated in Beagles using the CAT assay to measure thrombin generation with tissue factor at a concentration of 5 pM for initiation. RESULTS: In healthy Beagles, the range of endogenous thrombin potential (ETP) was 238.7-414.0 nM/min (mean ± SD, 340.4 ± 63.1 nM/min). ETP intra-assay and interassay variations were 7.1% and 12.9%, respectively. In vitro, a UFH concentration ≥0.4 U/mL resulted in total inhibition of thrombin generation. In vivo, the maximal effect of UFH on ETP was observed at 170 ± 36 minutes (range, 120-210 minutes) and resulted in a decrease in ETP of 38.5 ± 7.8% (range, 26.5-50.3%). In 210-420 minutes, ETP returned to baseline in 5 dogs. CONCLUSION: Our study demonstrates that thrombin generation can be measured in canine plasma and may be useful in assessing the degree of anticoagulation provided by UFH.

Prekallikrein deficiency in a dog.

Prekallikrein (PK) deficiency is an uncommon disorder in dogs. In this report, we describe a case of a dog that was referred for neurological defects and had a prolonged activated partial thromboplastin time (aPTT) and normal prothrombin time (PT) with no hemostatic defects. By using human PK-deficient plasma, the dog was diagnosed to have PK deficiency. The nucleotide sequence of normal canine PK cDNA was determined and compared with the genomic sequences of PK in the affected dog. The comparison revealed that the dog had a point mutation in exon 8 that leads to an amino acid substitution in the fourth apple domain of PK. This is the first report showing a point mutation of PK in a dog with PK deficiency.

Tissue factor activated thromboelastography correlates to clinical signs of bleeding in dogs.

The ability of a laboratory assay to correlate to clinical phenotype is crucial for the accurate diagnosis and monitoring of haemostasis and is therefore challenging with currently used routine haemostasis assays. Thromboelastography (TEG) is increasingly used to evaluate haemostasis in humans and may well be of value in the workup of dogs suspected of having a haemostatic disorder. This study was undertaken to evaluate prospectively how tissue factor (TF) activated TEG correlated to clinical signs of bleeding in dogs, compared to a routine coagulation profile. A prospective case-control study was performed over a 2 year period from 2004-2006. Eligible dogs were those where the primary clinician requested a coagulation profile to evaluate haemostasis. The dogs were simultaneously evaluated with a TF-activated TEG assay. Twenty-seven dogs, characterised as hypo-coagulable based on the TEG parameter G (<3.2 Kdyn/cm(2)), were included in the study as cases. Size matched control groups of TEG normo- (G=3.2K-7.2 Kdyn/cm(2)) and hyper-coagulable (G>7.2 Kdyn/cm(2)) dogs were selected retrospectively from the eligible dogs. For all dogs, clinical signs of bleeding were noted at time of analysis. There were statistically significant differences between all TEG values of hypo- and normo- and hyper-coagulable dogs. Thromboelastography correctly identified dogs with clinical signs of bleeding with a positive predictive value (PPV) of 89% and a negative predictive value (NPV) of 98% based on G alone. In comparison, the coagulation profile had a PPV between 50-81% and a NPV between 92-93% for detection of bleeding, depending on the observer. In conclusion, a TF-activated TEG G value<3.2K dyn/cm(2) correctly identified dogs with clinical signs of bleeding with very high PPV and NPV, irrespective of observer. The findings strongly suggest that TF- activated TEG may be of value in the workup of dogs suspected of having a haemostatic disorder.

Evaluation of human recombinant tissue factor-activated thromboelastography in 49 dogs with neoplasia.

BACKGROUND: Abnormal routine coagulation assay results have been reported to be common in veterinary patients with neoplasia, but the overall hemostatic functional state, including hypercoagulability, has not been described. HYPOTHESIS: The overall hemostatic functional state, including hypercoagulability, can be assessed in dogs with neoplasia by tissue factor (TF)-activated thromboelastography (TEG). ANIMALS: Thirty-six dogs with malignant neoplasia and 13 dogs with benign neoplasia presented to the Small Animal Veterinary Teaching Hospital, The University of Copenhagen, Frederiksberg, Denmark. METHODS: Prospective study evaluating the overall hemostatic functional state in dogs with neoplasia by a newly validated TF-activated TEG assay and routine coagulation parameters activated partial thromboplastin time (aPTT), prothrombin time (PT), platelet count, and D-dimer concentration. RESULTS: Hemostatic dysfunction was observed in 28/49 (57%) dogs with neoplasia. Twenty-four were dogs with malignant neoplasia, the majority of which 18/36 (50%) were hypercoagulable, whereas 6/36 (17%) were hypocoagulable. All hypocoagulable dogs had metastatic disease. The proportion of dogs with altered hemostasis was significantly different between dogs with malignant and benign neoplasia. CONCLUSIONS AND CLINICAL IMPORTANCE: TF-activated TEG detected hypercoagulable and hypocoagulable states in this population of dogs with neoplasia. The most common hemostatic abnormality in dogs with malignant neoplasia was hypercoagulability. These findings suggest that this novel hemostatic function test may be of value as a cage side method for the assessment of overall hemostatic function in dogs with cancer, including the detection of both hyper- and hypocoagulable states as well as mixed disorders.