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Abstract

Objective—To assess a point-of-care instrument for identification of primary hemostatic disorders in dogs.

Animals—29 healthy dogs and 23 nonanemic dogs with primary hemostatic disorders (thrombocytopenia, n = 6; thrombopathia, 6; von Willebrand disease [vWD], 11).

Procedure—Citrated blood was obtained and closure times (CT) were determined by measuring the time required for occlusion of an aperture by a platelet plug within the point-of-care instrument. Reference ranges for CT were established, and CT were determined for dogs with primary hemostatic disorders.

Results—CT measured with adenosine diphosphate as the platelet agonist (ADP-CT) ranged from 52 to 86 seconds for healthy dogs (mean ± 2 SD, 67 ± 7.8 seconds; median, 65 seconds), and CT measured with epinephrine as the agonist (EPI-CT), from 97 to 225 seconds (151 ± 38 seconds; 148 seconds). In thrombocytopenic dogs, ADP- and EPI-CT were prolonged (> 165 and > 264 seconds, respectively). Five of 6 dogs with thrombopathia had prolonged ADP-CT, whereas EPI-CT was prolonged in all 6 dogs. In all dogs with vWD, ADP-CT was prolonged; EPI-CT was prolonged in 10 of these dogs. Sensitivity and specificity for ADP-CT were 95.7 and 100%, respectively, and positive and negative predictive values, 100 and 96.7%, respectively, whereas for EPI-CT, these values were 95.7 and 82.8%, respectively, and 81.5 and 96%, respectively.

Conclusions and Clinical Relevance—The point-ofcare instrument allowed quick assessment of primary hemostasis in nonanemic dogs. Use of this instrument may be helpful for making decisions regarding management of dogs with primary hemostatic disorders. (Am J Vet Res 2001;62:652–658)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate primary hemostasis following administration of desmopressin acetate (DDAVP) to Doberman Pinschers with type-1 von Willebrand disease (vWD).

Animals—16 nonanemic Doberman Pinschers with type-1 vWD.

Procedure—Closure time (CT), defined as time required for occlusion of an aperture by a platelet plug assessed within the point-of-care instrument, plasma von Willebrand factor (vWF) concentration, and buccal mucosal bleeding time (BMBT) were determined before and 1 hour after administration of DDAVP (1 µg/kg, SC).

Results—Baseline closure times measured with adenosine diphosphate ([ADP-CT], 108 to > 300 seconds; reference range, 52 to 86 seconds) and epinephrine ([EPI-CT], 285 to > 300 seconds; 97 to 225 seconds) as platelet agonists were prolonged in all dogs. Following DDAVP administration, ADP-CT (59 to 186 seconds) was significantly shortened from baseline, but there was no decrease in EPI-CT. Although mean plasma vWF concentration increased significantly after DDAVP administration, only 1 dog had an increase of > 35 U/dL. There was no correlation between increase in plasma vWF concentration and shortening of the ADP-CT. Baseline BMBT was prolonged in 12 of 14 dogs, with significant shortening of BMBT after DDAVP administration in 6 of 7 dogs. In vitro replacement of vWF-deficient plasma with plasma from an unaffected dog shortened the ADP-CT, whereas in vitro addition of DDAVP had no effect.

Conclusions and Clinical Relevance—Administration of DDAVP to Doberman Pinschers with type-1 vWD resulted in improved hemostatic function, as assessed by the point-of-care instrument and shortening of BMBT, despite minimal increase in plasma vWF concentration. (Am J Vet Res 2002;63:1700–1706)

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in American Journal of Veterinary Research

Abstract

Objective—To compare effects of 3.8% sodium citrate and anticoagulant citrate dextrose solution National Institutes of Health formula A (ACD-A) on pH, extracellular ionized calcium (iCa) concentration, and platelet aggregation in canine platelet-rich plasma (PRP).

Sample Population—Samples from 12 dogs.

Procedures—Blood samples were collected into 3.8% sodium citrate (dilution, 1:9) and ACD-A (dilution, 1:5). Platelet function, pH, and iCa concentration were evaluated in PRP. Platelet agonists were ADP, γ-thrombin, and convulxin; final concentrations of each were 20μm, 100nM, and 20nM, respectively. Washed platelets were used to evaluate effects of varying the pH and iCa concentration.

Results—Mean pH and iCa concentration were significantly greater in 3.8% sodium citrate PRP than ACD-A PRP. Platelet aggregation induced by ADP and γ-thrombin was markedly diminished in ACD-A PRP, compared with results for 3.8% sodium citrate PRP. Anticoagulant had no effect on amplitude of convulxin-induced platelet aggregation. In washed platelet suspensions (pH, 7.4), there were no differences in amplitude of platelet aggregation induced by convulxin or γ-thrombin at various iCa concentrations. Varying the pH had no effect on amplitude of aggregation induced by convulxin or γ-thrombin, but the aggregation rate increased with increasing pH for both agonists.

Conclusions and Clinical Relevance—Aggregation of canine platelets induced by ADP and γ-thrombin was negligible in ACD-A PRP, which suggested an increase in extraplatelet hydrogen ion concentration inhibits signaling triggered by these agonists but not by convulxin. Choice of anticoagulant may influence results of in vitro evaluation of platelet function, which can lead to erroneous conclusions.

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in American Journal of Veterinary Research

Abstract

Objective—To assess the effect of desmopressin (DDAVP) administration in Doberman Pinschers with type 1 von Willebrand disease (vWD) on plasma von Willebrand factor (vWF) multimers through determination of vWF collagen binding activity (vWF:CBA; a functional vWF assay dependent on the presence of high–molecular-weight [HMW] multimers), comparison of vWF antigen concentration (vWF:Ag) to vWF:CBA, and vWF multimer size distribution.

Animals—16 Doberman Pinschers with type 1 vWD and 5 clinically normal control dogs.

Procedure—Plasma vWF:Ag and vWF:CBA assays and vWF multimer analysis were performed before and 1 hour after administration of DDAVP (1 µg/kg, SC).

Results—Following DDAVP administration, dogs with type 1 vWD had an increase in mean baseline values of plasma vWF:Ag and vWF:CBA from 10% to 17% for both variables. The mean vWF Ag:CBA ratio at baseline (0.95) was similar after DDAVP administration (0.97), indicating concordant increases in plasma vWF concentration and activity. In control dogs, mean plasma vWF:Ag and vWF:CBA increased from baseline values of 64% to 113% and 58% to 114%, respectively, and the vWF Ag:CBA ratios were unchanged (1.1 vs 1.0) after DDAVP administration. Plasma vWF multimer analysis revealed proportional increases in band intensity for all multimer sizes following DDAVP administration, in comparison to baseline for the control dogs and Doberman Pinschers with vWD, consistent with vWF Ag:CBA ratios of approximately 1.

Conclusions and Clinical Relevance—Beneficial effects of DDAVP on primary hemostasis in Doberman Pinschers with type 1 vWD cannot be explained by preferential increases in HMW vWF multimers. (Am J Vet Res 2005;66:861–867)

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in American Journal of Veterinary Research

Abstract

Objective—To determine clinical features and outcome associated with use of a hemoglobin-based oxygen-carrying (HBOC) solution in cats.

Design—Retrospective study.

Animals—72 cats.

Procedure—Medical records of cats that received an HBOC solution were reviewed.

Results—The most common clinical signs and physical examination findings prior to infusion of the HBOC solution were associated with anemia; vomiting, neurologic signs, and respiratory abnormalities were also detected. The HBOC solution was given as a supportive measure in treatment of anemia in 70 cats, most often because compatible blood was not readily available. There were 80 separate HBOC solution infusion events (mean dose, 14.6 ml/kg [6.6 mg/lb]; mean rate of infusion, 4.8 ml/kg [2.2 ml/lb] per hour). Improvements in 37 of 43 of the more closely monitored cats included increased rectal temperature, blood hemoglobin concentration, blood pressure, appetite, and activity. Adverse events in 44 cats included pulmonary edema (n = 8), pleural effusion (21), mucous membrane discoloration (21), pigmenturia (11), vomiting (4), and neurologic abnormalities (4). Twenty-three cats were discharged from the hospital, and 49 cats died or were euthanatized. Necropsy examination of 23 cats did not reveal evidence of renal or hepatic toxicosis associated with HBOC administration.

Conclusions and Clinical Relevance—Although administration of an HBOC solution may provide temporary support to anemic cats, the development of pulmonary edema or pleural effusion potentially associated with rapid infusion rate and large volume of infusion of the HBOC solution should be investigated further before use of the solution can be recommended in cats. (J Am Vet Med Assoc 2002;221:96–102)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate a canine D-dimer point-of-care (cD-d POC) test kit for use in healthy dogs and dogs with disseminated intravascular coagulation (DIC), thromboembolic disease (TED), and hemorrhage.

Animals—12 healthy dogs, 18 dogs with DIC, 23 dogs with TED (19 acute and 4 chronic), and 18 dogs with hemorrhage.

Procedure—The cD-d POC, canine D-dimer ELISA (cD-d ELISA), human D-dimer latex agglutination (hD-d LA), and fibrin degradation product (FDP) tests were performed on citrated plasma.

Results—All healthy dogs had negative cD-d POC test results and mean cD-d ELISA value of 0.2 U/mL. All dogs with DIC had positive cD-d POC test results and mean cD-d ELISA value of 44 U/mL. Dogs with acute TED had a mean cD-d ELISA value of 34 U/mL, and 17 of 19 had positive cD-d POC test results. Mean cD-d ELISA value in dogs with hemorrhage was 14 units/mL, and 15 of 18 had positive cD-d POC test results. The cD-d ELISA values in dogs with hemorrhage were significantly higher than those of healthy dogs but lower than those of dogs with DIC and acute TED. The cD-d POC, cD-d ELISA, and hD-d LA tests were comparable in differentiating healthy dogs from dogs with DIC, acute TED, or hemorrhage and appeared to be superior to measurement of FDPs.

Conclusions and Clinical Relevance—The cD-d POC test kit can be quickly and easily used and reliably detects dogs with DIC or acute TED. Positive results may also be seen in dogs with internal hemorrhage. (Am J Vet Res 2003;64:1562–1569)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of prednisone alone, compared with a combination of prednisone and vincristine, on platelet counts in bleeding dogs with severe primary immune-mediated thrombocytopenia (IMT).

Design—Prospective case study.

Animals—24 dogs with severe primary IMT.

Procedure—All dogs received immunosuppressive doses of prednisone (1.5 to 2 mg/kg [0.7 to 0.9 mg/lb] of body weight, PO, q 12 h). In addition, 12 dogs received a single dose of vincristine (0.02 mg/kg [0.01 mg/lb], IV). Platelet count, transfusion requirement, and outcome were monitored. A response was defined as an increase in platelet count to ≥ 40,000/µl. Dogs in the prednisone group that failed to respond received 1 dose of vincristine on day 7.

Results—Dogs that received prednisone and vincristine had a significantly faster increase in platelet count to ≥ 40,000/µl than dogs that received prednisone alone (mean ± SD, 4.9 ± 1.1 vs 6.8 ± 4.5 days, respectively). A similarly rapid response was observed in dogs that received vincristine on day 7 after treatment with prednisone alone failed. Furthermore, duration of hospitalization was reduced in the vincristine group, compared with the prednisone group (5.4 ± 0.3 vs 7.3 ± 0.5 days, respectively). No adverse effects attributable to vincristine were observed in any dog.

Conclusions and Clinical Relevance—Administration of combined vincristine and prednisone is associated with more rapid increase in platelet numbers and shortened duration of hospitalization in dogs with IMT, compared with use of prednisone alone. Early use of vincristine seems warranted in dogs with severe primary IMT. (J Am Vet Med Assoc 2002; 220:477–481)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To document reasons for use of fresh frozen plasma (FFP) in dogs and determine variables that apparently triggered the decision to use FFP.

Design—Retrospective study.

Animals—74 dogs.

Procedure—Medical records of dogs that received FFP at a veterinary teaching hospital during a 3-month period were reviewed.

Results—The 74 dogs underwent 144 transfusion episodes (TE; a TE was defined as 1 day of transfusion therapy) and received 252 units (120 ml/unit) of FFP. Fresh frozen plasma was administered to provide coagulation factors (67 TE), albumin (91), alphamacroglobulin (15), or immunoglobulins (19); for some TE, multiple clinical indications were identified. Variables that apparently triggered the decision to administer FFP included active hemorrhage with or without prolongation of coagulation times, low total plasma protein concentration, persistent vomiting associated with pancreatitis, and sepsis. Mean doses of FFP for each indication were between 8.5 and 9.4 ml/kg (3.9 and 4.3 ml/lb). Small dogs were generally given higher doses (mean dose, 13.9 ml/kg [6.3 ml/lb]) than large dogs (mean dose, 5.1 ml/kg [2.3 ml/lb]). Fifty (68%) dogs were alive at the time of discharge from the hospital.

Conclusions and Clinical Relevance—Results suggest that FFP plays an important role in the care of critically ill dogs. Because the supply of FFP is limited, guidelines for when administration of FFP may be clinically useful should be developed. (J Am Vet Med Assoc 2001;218:1449–1455)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effects of nonsteroidal anti-inflammatory drugs of various cyclooxygenase selectivities on hemostasis and prostaglandin expression in dogs.

Animals—8 client-owned dogs with clinical signs of osteoarthritis.

Procedures—Dogs received aspirin (5 mg/kg, PO, q 12 h), carprofen (4 mg/kg, PO, q 24 h), deracoxib (2 mg/kg, PO, q 24 h), and meloxicam (0.1 mg/kg, PO, q 24 h) for 10 days each, with an interval of at least 14 days between treatments. On days 0 and 10, blood was collected for platelet aggregation assays, thrombelastography, and measurement of lipopolysaccharide-stimulated prostaglandin E2, platelet thromboxane B2 (TXB2), and free serum TXB2 and 6-keto-prostaglandin F (PGF)-1α concentrations.

Results—Platelet aggregation decreased after treatment with aspirin and carprofen, whereas significant changes from baseline were not detected for the other drugs tested. Thrombelastograms obtained after treatment with carprofen revealed decreased maximum amplitude and α-angle, suggesting hypocoagulability. Maximum amplitude and coagulation index increased after treatment with deracoxib. Plasma concentrations of prostaglandin E2 decreased after treatment with carprofen or deracoxib, and platelet TXB2 production increased after treatment with aspirin. Serum concentrations of the prostacyclin metabolite 6-keto-PGF-1α did not change significantly after treatment with any of the drugs, although the ratio of free TXB2 to 6-keto-PGF-1α decreased slightly after treatment with carprofen and increased slightly after treatment with deracoxib.

Conclusions and Clinical Relevance—At the dosages tested, treatment with meloxicam affected platelet function minimally in dogs with osteoarthritis. Treatment with carprofen decreased clot strength and platelet aggregation. Clot strength was increased after treatment with deracoxib.

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in American Journal of Veterinary Research

Abstract

Objective—To characterize in vitro coagulation status in a cohort of dogs with extrahepatic biliary tract obstruction (EHBO) and to evaluate these patients for hypercoagulability by means of thromboelastography.

Design—Prospective cohort study.

Animals—10 dogs with EHBO and 19 healthy control dogs.

Procedures—Partial or complete EHBO was confirmed via exploratory celiotomy. Venous blood samples were collected for evaluation of prothrombin time (PT) and activated partial thromboplastin time (APTT); fibrinogen and D-dimer concentrations; protein C and antithrombin activities; and factor VII, VIII, and XI coagulant activities in plasma as well as thromboelastography in whole blood. Thromboelastography variables were measured from the thromboelastography tracing, and a coagulation index was calculated. Thromboelastography results were compared with those of healthy control dogs previously evaluated by the same laboratory.

Results—Hypercoagulability was diagnosed in all dogs with EHBO on the basis of a high coagulation index. Thromboelastography variables, including maximal amplitude, α-angle, and coagulation index, were significantly higher, and K (clot formation time) and R (reaction time) were significantly lower in these dogs than in control dogs. All dogs with EHBO had PT and APTT within respective reference ranges. Plasma D-dimer and fibrinogen concentrations were above reference ranges in 8 and 7 dogs, respectively, and protein C and antithrombin activities were below reference ranges in 3 and 1 dogs, respectively.

Conclusions and Clinical Relevance—In vitro hypercoagulability was commonly detected in dogs with naturally occurring EHBO. The traditional view of EHBO as a disease that causes hypocoagulability may need to be reconsidered.

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in Journal of the American Veterinary Medical Association