COAGULATION ASSESSMENT: UNDERUTILIZED DIAGNOSTIC TOOLS IN ZOO AND AQUATIC ANIMAL MEDICINE

Point-of-care viscoelastic coagulation monitor parameters in Amazon parrots (Amazona spp.)

OBJECTIVE

To evaluate the feasibility of the point-of-care viscoelastic coagulation monitor (VCM) in Amazon parrots (Amazona spp.) and describe the parameters with fresh whole-blood samples in healthy Amazon parrots.

DESIGN

A total of 18 Amazon parrots were enrolled. Physical examinations, a CBC, and a biochemistry profile, including bile acids, were performed on all parrots. VCM tracings were obtained at the time of venipuncture for baseline laboratory work.

MEASUREMENTS AND MAIN RESULTS

The median clot time was 2102 seconds (range: 38.6-3599 s), median clot formation time was 929 seconds (range: 21.4-1711 s), median alpha angle was 20 (range: 6-67), and the median maximum clot formation was 8.5 (range: 0-36). The median lysis index at 30 minutes (LI30) was 100 (range: 98-100), and the median lysis index at 45 minutes (LI45) was 100 (range: 90-100). Of 18 samples, alpha angles were not reported in 7 samples, LI30 was not reported in 10 samples, and LI45 was not reported in 12 samples. Of the qualitative curves, 6 reflected normal mammalian curves, and the remainder were consistent with a hypocoaguable state.

CONCLUSIONS

The results were markedly variable, with the majority of VCM tracings being hypocoagulable in comparison with reference intervals established for dogs and cats. Using these protocols, the VCM is not reliable in Amazon parrots. Future areas of investigation include altering the temperature during sample analysis, the use of activators, or an exchange of clotting reagents for an extrinsic pathway activator, which may contribute to the success of this device in avian species.

INVESTIGATION OF A POINT-OF-CARE VISCOELASTIC COAGULATION MONITOR AND ITS COMPARISON TO THROMBOELASTOGRAPHY IN CLINICALLY HEALTHY AFRICAN ELEPHANTS (LOXODONTA AFRICANA)

Elephant endotheliotropic herpesvirus (EEHV) can induce fatal hemorrhagic disease (HD) in African elephants (Loxodonta africana). Once clinical signs develop, progression is rapid, even with aggressive treatment. There is a critical need to develop point-of-care diagnostic tests to aid in identification of EEHV-HD prior to the onset of overt clinical signs. Study objectives were to investigate a novel, point-of-care viscoelastic coagulation monitor (VCM Vet), compare the results to thromboelastography (TEG), and report traditional hemostatic analytes in adult African elephants. Whole blood was collected from seven clinically healthy elephants (four females and three males, 18-47 yr) and analyzed in duplicate via VCM Vet and kaolin-activated TEG 1-3 and 30 min following collection, respectively. Separated plasma was frozen for ancillary coagulation testing. Both analyses generated quantifiable clotting reactions with variables (median [range]) describing clot formation rate (VCM Vet, clot time = 682 s [530-987 s], clot formation time = 244 s [186-744 s], Alpha = 40° [14-47°]; TEG, reaction time = 6.2 min [3.7-11.8 min], kinetic time = 1.3 min [0.9-2.6 min], Alpha = 70° [57-77°]), clot strength (VCM Vet, maximum clot formation = 34 units [20-45 units]; TEG, maximum amplitude = 75 mm [69-80 mm], shear elastic modulus strength = 14.7 Kdynes/s [11.3-19.5 Kdynes/s]), and clot lysis (VCM Vet, lysis index at 30 min = 100% [100-99%], lysis index at 45 min = 98% [95-100%]; TEG, lysis index at 30 min = 0% [0-0.4%], lysis index at 60 min = 1.4% [0-2.6%]) recorded. Additional testing (median [range]) included D-dimer concentration (33 ng/ml [28-94 ng/ml]), prothrombin time (12.4 s [12.2-13.2 s]), activated partial thromboplastin time (17.2 s [14.2-18.8 s]), and fibrinogen concentration (297 [282-383] mg/dL). Tracings generated by VCM Vet and TEG were clinically similar, and there was visual agreement and minimal difference between quantitative variables for duplicate tests. VCM Vet is a promising, user-friendly tool for use in identification and management of coagulopathies in African elephants.

Viscoelastic Coagulation Testing in Exotic Animals

Whole blood viscoelastic coagulation testing (VCT) allows global assessment of hemostasis and fibrinolysis. Although not widely used in exotic animal practice, VCT has been used in exotic animal research settings. Differences in patient demographics and analytical variables can result in dramatically different results with the same analyzer. To improve the utility of VCT in exotic animal medicine, standardization of protocols is necessary to facilitate the establishment of reference intervals. Despite these challenges, the quantitative/qualitative nature of VCT has already proved its real-world value to some clinicians.

POINT-OF-CARE AND STANDARD LABORATORY REFERENCE INTERVALS FOR COAGULATION VALUES IN ASIAN ELEPHANTS (ELEPHAS MAXIMUS): VARIATION BY AGE CLASS, SEX, AND TIME TO CENTRIFUGATION

In Asian elephants (Elephas maximus), elephant endotheliotropic herpesvirus causes significant calf mortality. Coagulation testing may aid veterinarians in early identification and management of hemostatic disorders. This study sought to establish reference intervals for select coagulation and platelet values. Blood was collected from clinically healthy Asian elephants (n = 63) in juvenile (≤15 yr old, n = 9), adult (>15 to ≤50 yr old, n = 41), and geriatric (>50 yr old, n = 13) age classes at seven institutions in Kanchanaburi Province, Thailand. Activated clotting time (ACT) was immediately assessed with a handheld analyzer, whereas remaining blood was stored at 5°C in sodium citrate and potassium EDTA collection tubes and transported to a central laboratory. Coagulation values were assessed on an automated blood coagulation analyzer, and platelet values were assessed on a hematology analyzer. Reference intervals were established for ACT, prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, platelet count, mean platelet volume, platelet distribution width, and plateletcrit according to the American Society for Veterinary Clinical Pathology guidelines. No significant differences were observed for any value when comparing sex and time to centrifugation. Plasma fibrinogen (P = 0.002) and platelets (P = 0.003) varied significantly by age class, with adults displaying the highest fibrinogen concentrations and geriatric individuals displaying the lowest platelet counts. The ACT kaolin cartridges resulted in high success rates (84.3% feasibility) compared with celite cartridges (4.8% feasibility). Further studies are warranted to stratify reference intervals in accordance with age class trends.