Current diagnostic trends in coagulation disorders among dogs and cats

Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer's solution or 6% tetrastarch 130/0.4

OBJECTIVE

To describe and compare prothrombin time (PT), activated partial thromboplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measurements in a hemorrhage/over-resuscitation model.

DESIGN

Randomized crossover study.

SETTING

University teaching hospital.

ANIMALS

Six cats.

INTERVENTIONS

Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR-no controlled hemorrhage and sham resuscitation; LRS-controlled hemorrhage and lactated Ringer's solution (LRS) for resuscitation; and Voluven-controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T - 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixed model approach (significance was P < 0.05).

MEASUREMENTS AND MAIN RESULTS

Total median blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 and T120 compared to NHR (P < 0.001). On TEG, the reaction time, kinetic time, and alpha-angle were within reference intervals for cats at all time points in all treatments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, and T120 during Voluven and at T60 and T120 during LRS compared to NHR (both P < 0.001). The HCT and platelet count were significantly lower at T60 and T120 during LRS and Voluven compared to NHR (P < 0.001).

CONCLUSIONS

Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strength may have been caused by hemodilution and platelet loss.

An Evaluation of Hemostatic Dysregulation in Canine Multicentric Lymphoma

Multiple hemostatic abnormalities are associated with paraneoplastic syndrome and some malignant tumors. Lymphoma is the most common hematopoietic neoplasm in dogs, sometimes associated with hemostatic changes. The objectives of this study were to evaluate the behavior of coagulation parameters in dogs with multicentric lymphoma compared with diseased dogs without lymphoma, to separately evaluate the effect of immunophenotype (B lymphoma versus T lymphoma) on the variables of interest as well as the effect of disease stage (stage II to IV versus stage V). Specifically, a cross-sectional study was performed with a matched comparison group considering 170 dogs with B or T lymphoma (group 1) and 170 dogs with no lymphoma or other neoplastic processes but other diseases (group 0). Eight coagulation parameters were evaluated: platelet count (Plt), activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen, fibrin/products of fibrinogen degradation (FDPs), fibrin D-dimers, and antithrombin (AT). Dogs with lymphoma showed prolonged PT and TT, decreased fibrinogen, increased FDP, and decreased Plt compared with group 0. The effect of disease stage was evaluated separately for dogs with stage II to IV lymphoma and dogs with stage V lymphoma; patients with stage II-IV lymphoma showed no significant differences, while in dogs with stage V lymphoma, a prolongation of PT and TT, a decrease in fibrinogen, an increase in FDPs and a decrease in Plt were found compared with the group 0. Finally, the comparison between B lymphoma and T lymphoma showed no significant differences in coagulation parameters between the two groups. Logistic regression analysis demonstrated that low fibrinogen and platelet levels were the most significant predictors of lymphoma in a cohort of canine patients. These hemostatic abnormalities in lymphoma appeared to be associated with the stage of the disease rather than the lymphoma immunophenotype. These findings pave the way for the possible scenario of lymphoma-associated fibrinolysis and the so far undescribed pattern of hyperfibrinolysis associated with the most severe stage of lymphoma.

Evaluation of platelet additive solution for prolonging storage of functional canine platelet concentrate

OBJECTIVE

To assess storage lesion development, platelet function, and bacterial growth in canine platelet concentrates (PCs) stored in a platelet additive solution (PAS) or a plasma control at 4°C for 21 days.

DESIGN

Prospective, ex vivo, experimental controlled study.

SETTING

University veterinary teaching hospital.

ANIMALS

Ten units of canine PCs collected from blood bank donations.

INTERVENTIONS

The PCs were separated into 2 bags, 1 containing 100% plasma and the other containing 35% plasma and 65% of a PAS (Plasma-Lyte A), and stored at 4°C for 21 days. At days 0, 7, 14, and 21, PCs were analyzed for the presence of swirling, aggregate formation, platelet counts, platelet indices, glucose, lactate, lactate dehydrogenase, Pvco2 , Pvo2 , aggregation via light aggregometry, activation percentages using flow cytometry, and bacterial growth.

MEASUREMENTS AND MAIN RESULTS

Cold-stored PCs in both PAS and plasma control maintained mean pH >6.8 and mean lactate <9.0 mmol/L over 21 days, with no difference in glucose utilization. Swirl was maintained in both solutions for most days (76/80 combined total samples), with no difference in aggregate formation between solutions. The Pvco2 was higher in plasma on all days (P < 0.001), with no difference in Pvo2 . Platelet indices did not reflect significant storage lesion development in either solution. Lactate dehydrogenase did not differ between solutions but did increase from day 7 to day 21. Mean maximal aggregation percentage was reduced overall but with no significant difference between solutions. The only observed difference in mean activation percentage between solutions was in PAS on day 7, which was significantly higher than plasma (P < 0.05). No bacterial growth occurred during storage.

CONCLUSIONS

Cold storage in PAS and plasma allowed PCs to be stored for up to 21 days with minimal storage lesion development, maintenance of platelet function, limited platelet activation, and no bacterial growth within stored bags.

Predictive Factors for Two-Year Survival in Dogs with Hepatobiliary Diseases: Importance of Clinical and Laboratory Monitoring

Long-term outcomes and survival predictors for different clinicopathologies (idiopathic chronic hepatitis, liver fibrosis, vacuolar hepatopathy) in dogs with hepatobiliary diseases are poorly described. In this study, ninety dogs were followed up for up to five years to investigate clinical factors that predict two-year survival in canine patients after liver biopsy. Univariate and multivariate analyses were performed based on clinical and laboratory data to determine the association between clinical and laboratory data and mortality rates. Overall, the one-, two-, and five-year mortality rates were 28.9%, 45.6%, and 78.9%, respectively. Univariate analysis indicated that male gender, ascites, elevated serum gamma-glutamyl transpeptidase (GGT), hypercholesterolemia, hypoalbuminemia, prolonged activated partial thromboplastin clotting time (aPTT), and prolonged thrombin clotting time (TT) were associated with an increased two-year mortality rate. Results from multivariate analysis demonstrated a significant association between male gender (p = 0.022), elevated serum GGT (p < 0.001), hypoalbuminemia (p < 0.001), and prolonged aPTT (p < 0.001) and an increased two-year mortality rate, regardless of the specific type of liver pathology. Elevated GGT was associated with the highest risk for increased two-year mortality (95% CI: hazard ratio 6.02-41.21). In conclusion, various clinical factors in dogs with liver diseases are useful for prognosis prediction.

Correlation Between D-Dimer Concentrations and Thromboelastography in Dogs With Critical Illness: A Retrospective, Cross-Sectional Study

A hospital-based, retrospective, cross-sectional study was performed to assess the correlation of kaolin-activated thromboelastography (TEG) with D-dimer concentrations in 59 dogs with critical illness. Dogs were included if they had one or more serious disease detected upon performing TEG and D-dimer concentration determination based on the same blood sample. According to the coagulation index (CI), the 59 dogs were divided into two groups: a hypercoagulable state, with CI > 4 (44 dogs) and a normocoagulable state, with CI < 4 (15 dogs). Moreover, the 44 dogs with CI > 4 were divided into three sub-groups according to the disease etiology, i.e., inflammatory/tumor (I/T: 25 dogs), hemodynamic compromise (H: 11 dogs), and both conditions (I/TH: 8 dogs). The median values (interquartile ranges) of the CI and D-dimer concentration were 5.46 (4.55–6.33) and 410.25 (74.63–2206.12) in the 44 dogs with CI > 4 and 3.29 (2.92–3.75) and 1164.7 (50–2250.05) in the 15 dogs with CI < 4, respectively. The D-dimer concentration was significantly increased over the reference value in the 44 dogs with a CI > 4, particularly in dogs in the I/T group. It was also significantly increased in the 15 dogs with a CI < 4. D-dimer concentrations did not correlate with any of the TEG parameters in any of the dogs. Given this lack of correlation, the D-dimer concentration may be limited as an indicator of a possible hypercoagulable state in dogs with critical illness.

Excitement-Induced Cutaneous Bleeding (Haematidrosis-like) in a Dog

A 15-month-old intact female Pitbull was referred because of recurrent, episodic, self-limiting, excitement-induced bleeding from nontraumatised skin. No abnormalities were detected upon physical examination. Subsequently, the dog went for a walk under the direct supervision of one of the authors, became overexcited and, after approximately five minutes, bloody liquid, with a patchy distribution, appeared along the hair shafts of the face and neck. The affected skin was congested, partially blanching on diascopy and bloody liquid was oozing from the follicular openings. Urticaria, dermographism and hypertension were excluded, the complete blood count and coagulation profile were within the reference ranges and an analysis of the bloody exudate confirmed its blood components. The cutaneous bleeding of the dog followed a self-limited course, with no episodes during the last two years. Clinical and laboratory findings and the long-term evolution of this dog bear striking similarities to haematidrosis, a rare human disease of multifactorial aetiology and equivocal pathogenesis.

Stability of ex vivo coagulation factor activity in never-frozen and thawed refrigerated canine plasma stored for 42 days

OBJECTIVE

The primary objective of this study was to document coagulation factor activity in canine "NEVER-FROZEN" and "THAWED" refrigerated plasma for the purposes of defining recommended expiration dates. We hypothesized that NEVER-FROZEN and THAWED refrigerated plasma would maintain >50% activity of coagulation factors V (FV), VII (FVII), VIII (FVIII), IX (FIX), X (FX), and von Willebrand factor antigen (vWF) and a concentration of fibrinogen above the lower bound of the reference interval (>0.982 g/L) for greater than 14 days but less than 42 days.

DESIGN

Prospective laboratory-based study.

SETTING

University teaching hospital blood bank.

ANIMALS

Ten canine plasma units derived from healthy client-owned blood donors.

INTERVENTIONS

Serial sampling (days 0, 1, 3, 5, 7, 10, 14, 17, 21, 24, 28, 32, 35, 39, 42) from NEVER-FROZEN and THAWED refrigerated canine plasma units was conducted for measurement of activities of FV, FVII, FVIII, FIX, FX, vWF, and fibrinogen concentrations using the ACL TOP 300. Plasma was defined as "suitable for transfusion" at a given time point if the entire 95% confidence interval for each factor was above 50% activity and above a fibrinogen concentration of 0.982 g/L.

MEASUREMENTS AND MAIN RESULTS

The lower bounds of the FVIII and vWF confidence intervals were above 50% up to and including day 32 for NEVER-FROZEN refrigerated plasma and day 28 for THAWED refrigerated plasma. Confidence intervals for FV, FVII, FIX, and FX remained above 50% activity at all time points. The lower bound of the fibrinogen concentration was <0.982 g/L on day 39 for NEVER-FROZEN refrigerated plasma and on day 35 for THAWED refrigerated plasma.

CONCLUSIONS

Refrigerated canine plasma from these 10 dogs retained coagulation factor activity above the limit that we defined as suitable for transfusion for up to 32 days when NEVER-FROZEN and 28 days when THAWED. Further studies should evaluate the clinical outcomes and effects on coagulation factor activity of dogs receiving refrigerated plasma transfusions.

Analysis of blood clotting with the total thrombus analysis system in healthy dogs

To date, coagulation tests are unable to reflect in vivo coagulation status in the same system, including platelet function, fibrin clot formation, and whole blood flow. The Total Thrombus Analysis System (T-TAS), which is a microfluidic assay that simulates conditions in vivo, measures whole blood flow at defined shear rates under conditions designed to assess platelet function (PL-chip) or coagulation and fibrin clot formation (AR-chip). The T-TAS records occlusion start time, occlusion time, and area under the curve. We evaluated this test in healthy control dogs. We also investigated the effect in vivo of acetylsalicylic acid (ASA), and the effect in vitro of an anticoagulation drug (dalteparin; low-molecular-weight heparin; LMWH). The CV of the AUC of both chips was good (CVs of 6.45% [PL] and 1.57% [AR]). The inhibition of platelet function by ASA was evident in the right-shift in the PL test pressure curve. The right-shift in the AR test pressure curves showed that the administration of LMWH inhibited both platelets and the coagulation cascade. The T-TAS may be useful in the evaluation of canine blood coagulation.

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.

Comparison between blood coagulability in the intra-atrial and peripheral regions during the acute phase after rapid atrial pacing

The changes in intra-atrial blood coagulability of acute phase after development of atrial fibrillation (AF) have not been elucidated in human. In the present study, blood coagulability were examined in the intra-atrial and peripheral regions during the acute phase after development of rapid atrial pacing (RAP) in experimentally created model dog similar to AF, using Total Thrombus-formation Analysis System (T-TAS) that is capable of comprehensively evaluating thrombogenicity in the bloodstream in the microvascular channel. According to the results, both the coagulating function-evaluating time to +10 kPa (T10) and occlusion time (OT) of the AR chip (chip for thrombus analysis mixed with coagulation and platelet) were significantly shortened in the atrial blood as early as 30 min after pacing (T10, 150.5 ± 40.5 s; OT, 212.4 ± 44.3 s) compared to the pre-pacing levels (T10, 194.5 ± 47.5 s; OT, 259.9 ± 49.5 s) (P<0.05). The OT of PL chip (chip for platelet thrombus analysis) was significantly shortened 30 min after pacing (231.8 ± 57.6 s), compared to the pre-pacing level (289.5 ± 96.0 s) (P<0.05). Meanwhile, none of T10 and OT of AR and PL chips showed any significant changes in the peripheral blood. The study demonstrated increase of blood coagulability 30 min after development of RAP. While no significant changes were observed in the peripheral blood in the present study, the outcome suggested that the anti-thrombus treatments are better to be started early after AF even if coagulability of the peripheral blood shows no change.

Factor XII deficiency is common in domestic cats and associated with two high frequency F12 mutations

Factor XII (FXII) is a coagulation protein that initiates surface-activation of the coagulation cascade in vitro. The protein's in vivo role, however, remains poorly defined. Factor XII deficiency, or Hageman trait, is a rare hereditary disorder that is not associated with bleeding, and wide variations in FXII activity (FXII:C) exist among healthy people. While FXII-deficient knockout mice appear to be resistant to arterial thrombosis, human F12 polymorphisms that influence FXII:C have not been associated with thrombotic risk in population surveys. Factor XII deficiency is a naturally occurring hereditary trait in domestic cats. We undertook phenotypic and genotypic analyses of FXII-deficient cats for comparative studies with the human disease counterpart. A retrospective review of feline submissions to our laboratory revealed that FXII deficiency is common in domestic cats, and also present in many different breeds. The trait has a geographic bias toward the Midwestern United States. Clinical history, coagulation assays, and samples for F12 sequencing were obtained from 26 FXII deficient cats. None of the cats had experienced abnormal bleeding and their residual FXII:C was related to F12 mutation number and mutation-type. We found 2 high frequency F12 mutations: an exon 13 missense mutation (c.1631G > C) and an exon 11 deletion mutation (c.1321delC), and additional sequence variants throughout the gene. Factor XII deficiency in pet cat populations provides an animal model system to help clarify the biologic actions and clinical relevance of FXII protein.

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

OBJECTIVE

To characterize disseminated intravascular coagulation (DIC), liver failure (LF), post-hepatic cholestasis (PHC), and anticoagulant rodenticide intoxication (ROD) in dogs using an immunoturbidimetric coagulation analyzer and to characterize the relationship between clinical bleeding and bleeding parameters.

DESIGN

Retrospective study (August 2014-July 2015).

SETTING

University teaching hospital.

ANIMALS

Forty-seven client-owned dogs diagnosed with DIC (n = 24), LF (n = 9), PHC (n = 5), or ROD (n = 9) based on history, clinical pathology, cytology, histopathology. or exploratory surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Median prothrombin time (PT), activated partial thromboplastin time (aPTT), and quantitative fribrinogen assay (QFA) were above the reference interval for DIC, LF, PHC and ROD with the exception of a normal QFA for LF. Clot curve analysis for DIC was characterized by elevated PT Delta, PT first derivative, and aPTT Delta, and normal for aPTT second derivative; all LF parameters were within the RI; all PHC parameters were above the RI; and ROD had elevated aPTT delta, but low aPTT second derivative. Coagulopathic bleeding recognized within the DIC group was characterized by median PT delta in mABS (milliabsorbance), first derivative and aPTT delta values in mABS within the RI at 35.0, 55.5 and 38, respectively. The nonbleeding DIC group median values of these same parameters were 189.5, 586.5 and 288, respectively.

CONCLUSIONS

The classically utilized indicators of secondary hemostasis, PT and aPTT, were prolonged within all 4 groups; DIC, LF, PHC and ROD as expected. Fibrinogen concentration was increased in both PHC and ROD, decreased in LF and increased but with a bimodal distribution in DIC that correlated with clinical bleeding. The degree of PT and aPTT prolongation did not correlate with clinical bleeding in the DIC group, however clot curve analysis, did reveal an association.

Comparison of chronological changes in blood characteristics in the atrium and peripheral vessels after the development of non-valvular atrial fibrillation

INTRODUCTION

Changes in blood characteristics in the atrium and peripheral vessels in patients with non-valvular atrial fibrillation (NVAF) are unclear. We investigated chronological changes in blood characteristics in the atrium and peripheral vessels in a dog model of NVAF by using a total thrombus-formation analysis system (T-TAS).

MATERIALS AND METHODS

In NVAF model dogs (n = 8, 390 bpm rapid atrial pacing), atrial and peripheral blood samples were collected. Using this blood, T-TAS was performed before and 1, 2, and 3 weeks after the onset of rapid atrial pacing.

RESULTS

Occlusion time (OT: time to +80 and +60 kPa in the AR and PL chips, respectively) and area under the flow pressure curve (AUC) were measured using the AR chip (for mixed white thrombus analysis) and PL chip (for platelet thrombus analysis). OT of the AR chip showed shortening as early as 1 week after NVAF onset, which continued for 3 weeks. OT of the PL chip showed significant shortening in atrium blood only 3 weeks after NVAF onset. By contrast, peripheral blood showed no significant changes in OT or AUC with both AR and PL chips.

CONCLUSIONS

In our dog model of NVAF, thrombus formation accelerated in the atrium as early as 1 week after NVAF onset and continued for 3 weeks, but no significant changes were found in peripheral blood. We conclude that antithrombotic therapy should be started early after NVAF onset even if no changes in coagulation activity are observed in peripheral blood.

Performance characteristics of the turbidimetric ACL-TOP CTS 300 coagulation analyzer in dogs and cats

OBJECTIVE

To evaluate the technical performance of the turbidimetric ACL-TOP CTS 300 coagulation analyzer (IL) in dogs and cats and to create reference intervals for standard and novel parameters.

DESIGN

Coagulation testing results from dogs and cats generated by the IL were prospectively compared with another mechanical clot detection system. Precision was documented and reference intervals were created for prothrombin time, activated partial thromboplastin time, and Clauss fibrinogen and D-dimer values, as well as for the quantitative clot curve parameters (high and low amplitude, delta, and first and second derivative curves). Clot curve signatures containing common artifacts due to lipemia, hemolysis, or preactivation were demonstrated.

ANIMALS

Residual frozen plasma from 20 dogs and 10 cats was used for method comparison; prospectively recruited healthy dogs (n = 48) and cats (n = 45) were used for reference interval and precision studies.

MEASUREMENTS AND MAIN RESULTS

Bland-Altman analysis showed a proportional positive bias in the IL compared with mechanical clot detection in dogs and a suggestion of a similar pattern in cats. Precision was good and met manufacturer's recommendations for all assays. Reference intervals are reported. Clot curve artifacts were similar in animals to those reported in people.

CONCLUSIONS

The turbidimetric system had a slight high proportional positive bias compared with mechanical clot detection. Thus, new reference intervals were generated including for novel parameters generated by clot curve analysis. Some preanalytical errors can be identified by inspection of clot curves. This robust novel technology compares favorably with mechanical endpoint detection methods and can be used in dogs and cats.

The effect of 3 resuscitative fluid therapies on hemostasis as measured by rotational thromboelastometry in dogs

BACKGROUND

Evidence suggests that administration of intravenous fluids impairs hemostasis. Thromboelastometry (TEM) may provide a more sensitive measure of the fluid effects on hemostasis than traditional coagulation tests.

OBJECTIVE

The study aim was to determine if resuscitative fluid therapy affects hemostasis, as measured by TEM.

MATERIALS AND METHODS

Using a randomized crossover design, 6 healthy dogs were administered intravenous colloid, crystalloid, and hypertonic saline at therapeutic doses. Whole blood samples were taken at baseline, 1, 4, and 8 h posttreatment for TEM analysis and measurement of PT, APTT, and fibrinogen. Univariate ANOVA on transformed data evaluated differences between groups and within groups. When significant differences were noted (P = .003), a Tukey test was performed.

RESULTS

A statistically significant interaction between individual dogs and treatment was noted for most TEM variables. There was a significant decrease in clot firmness from baseline in the TEM assessment of the intrinsic pathway. Colloid treatment correlated with significantly higher clot firmness in the TEM extrinsic pathway assessment, which decreased over time, and PT was significantly shorter in colloid-treated dogs. Overall, PT was significantly prolonged at one hour; however, all PT values were within the RI. The fibrinogen concentration was significantly different between all treatments.

CONCLUSIONS

Clinically relevant doses of resuscitative fluids resulted in a decreased clot firmness in the intrinsic pathway, as measured by TEM, which affected hemostatic variables in healthy dogs. There was also a significant individual response to treatment. The changes noted in this study are not expected to result in clinically apparent bleeding.

HEREDITARY FACTOR VII DEFICIENCY IN THE ASIAN ELEPHANT (ELEPHAS MAXIMUS) CAUSED BY A F7 MISSENSE MUTATION

Hereditary disorders and genetic predispositions to disease are rarely reported in captive and free-ranging wildlife, and none have been definitively identified and characterized in elephants. A wild-caught, 41-yr-old male Asian elephant ( Elephas maximus ) without an apparent increased bleeding tendency was consistently found to have prolonged prothrombin times (PTs, mean=55±35 s) compared to 17 other elephants (PT=10±2 s). This elephant's partial thromboplastin times (PTT) fell within the normal range of the other elephants (12-30 s). A prolonged PT in the presence of a normal PTT suggests disruption of the extrinsic pathway via deficiency of coagulation Factor VII (FVII). This elephant's plasma FVII activity was very low (2%) compared to that of 15 other elephants (57-80%), but other coagulation factors' activities did not differ from the control elephants. Sequencing of genomic DNA from ethylenediaminetetraacetic acid blood revealed a single homozygous point mutation (c.202A>G) in the F7 gene of the FVII deficient elephant that was not present in unrelated elephants. This mutation causes an amino acid substitution (p.Arg68Gly) that is predicted to be deleterious. Two living offspring of the affected elephant were heterozygous for the mutation and had normal plasma FVII activities and coagulation profiles. Tissue from a third offspring, a deceased calf, was utilized to show that it was also a heterozygote. A DNA test has been developed to enable the screening of additional elephants for this mutation. Consistent with FVII deficiency investigations in other species, the condition did not cause a serious bleeding tendency in this individual elephant.

Establishment of reference values for various coagulation tests in healthy Florida manatees (Trichechus manatus latirostris) and evaluation of coagulation in debilitated manatees during rehabilitation

OBJECTIVE

To establish reference ranges for coagulation parameters in healthy Florida manatees (Trichechus manatus latirostris) and compare results with those for debilitated manatees undergoing treatment at a rehabilitation facility.

DESIGN

Prospective study.

ANIMALS

29 healthy manatees and 45 debilitated manatees with various diseases.

PROCEDURES

Manatees considered healthy on the basis of results of physical examination, CBC, and serum biochemical analysis underwent coagulation testing including measurement of prothrombin time, partial thromboplastin time, D-dimer concentration, platelet count, and fibrinogen concentration to establish reference ranges. For comparison, a group of manatees undergoing rehabilitation was also tested, and the results were compared. Thromboelastography was also performed on some animals.

RESULTS

Values for D-dimer concentration were significantly higher in debilitated versus healthy animals. There was no significant difference for prothrombin time, partial thromboplastin time, platelet count, or fibrinogen concentration between groups. Thromboelastography was performed on 8 healthy animals.

CONCLUSIONS AND CLINICAL RELEVANCE

Reference ranges were established for various tests of coagulation that may assist clinicians during the initial evaluation and rehabilitation of Florida manatees. Future research to evaluate the effect of specific disease processes on the coagulation cascade is recommended.