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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)

Full access
in American Journal of Veterinary Research

Summary

Although nearly all domestic shorthair and longhair cats have type-A blood (> 99%), the frequency of blood type B in various feline breeds ranges from 0 to 59%. All blood-type-B cats have strong natural alloantibodies, predominantly of the IgM class, whereas blood-type-A cats have low alloantibody titers of the IgG and IgM classes. We therefore studied the efficacy and safety of transfusing 20 ml of matched and mismatched 14C-potassium cyanate-labeled blood to cats. In autologous and allogeneic matched transfusions of blood-type-A and type-B cats, the half-life of labeled erythrocytes proved to be similar (29 to 39 days). In contrast, type-B erythrocytes transfused into 5 blood-type-A cats had a mean (± sd) half-life of only 2.1 ± 0.2 days and induced minor transfusion reactions. Half of the type-A blood given to 4 blood-type-B cats was destroyed within minutes to 6 hours (mean ± sd = 1.3 ± 2.3 hours), depending on the alloantibody titer. After 1 day, none of the labeled erythrocytes were detected. Mismatched transfusions in blood-type-B cats caused marked transient reactions including systemic anaphylactic signs (hypotension, bradycardia, apnea, urination, defecation, vomiting, and severe neurologic depression) and hemolytic signs (hemoglobinemia and pigmenturia) associated with severe reduction in plasma alloantibody titer and complement activity.

We conclude that the rapid destruction of type-A erythrocytes transfused into blood-type-B cats predominantly occurs intravascularly and is complement- and IgM-mediated, whereas type-B erythrocytes administered to blood-type-A cats are mostly extravascularly hemolysed by a process involving small amounts of IgG and IgM, but without marked complement activation. Thus, any first or subsequent AB-mismatched transfusions are ineffective and life threatening. We therefore recommend the practice of blood typing or cross-matching prior to transfusing blood in cats to prevent any incompatibility reactions and to assure efficacy.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate a point-of-care coagulation analyzer (PCCA) in dogs with coagulopathies and healthy dogs.

Animals—27 healthy and 32 diseased dogs with and without evidence of bleeding.

Procedure—Prothrombin time (PT), activated partial thromboplastin time (aPTT), and activated clotting time (ACT) were determined, using a PCCA and standard methods.

Results—Using the PCCA, mean (± SD) PT of citrated whole blood (CWB) from healthy dogs was 14.5 ± 1.2 seconds, whereas PT of nonanticoagulated whole blood (NAWB) was 10.4 ± 0.5 seconds. Activated partial thromboplastin time using CWB was 86.4 ± 6.9 seconds, whereas aPTT was 71.2 ± 6.7 seconds using NAWB. Reference ranges for PT and aPTT using CWB were 12.2 to 16.8 seconds and 72.5 to 100.3 seconds, respectively. Activated clotting time in NAWB was 71 ± 11.8 seconds. Agreement with standard PT and aPTT methods using citrated plasma was good (overall agreement was 93% for PT and 87.5% for aPTT in CWB). Comparing CWB by the PCCA and conventional coagulation methods using citrated plasma, sensitivity and specificity were 85.7 and 95.5% for PT and 100 and 82.9% for aPTT, respectively. Overall agreement between the PCCA using NAWB and the clinical laboratory was 73% for PT and 88% for aPTT. Using NAWB for the PCCA and citrated plasma for conventional methods, sensitivity and specificity was 85.7 and 68.4% for PT and 86.7 and 88.9% for aPTT, respectively.

Conclusions and Clinical Relevance—The PCCA detected intrinsic, extrinsic, and common pathway abnormalities in a similar fashion to clinical laboratory tests. (Am J Vet Res 2001;62:1455–1460)

Full access
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)

Full access
in American Journal of Veterinary Research

Summary

Erythrocyte pyruvate kinase (pk) deficiency was first described in Basenjis 20 years ago. Although the approach to diagnosis had not been well established, a screening program to detect heterozygotes was thought to have eliminated pk deficiency from the Basenjis of the United States. Four not closely related Basenjis with severe chronic hemolytic anemia, from various parts of the United States, were studied. Their pcv ranged from 16 to 25% and their reticulocyte count was always above 15%. A progressive osteosclerosis was seen in all of the Basenjis and hepatic failure developed in 2 of them. The erythrocyte intermediary metabolite patterns indicated a glycolytic defect at the pk step. Erythrocyte pk activities were markedly increased in the anemic Basenjis, compared with those of a control group, but the enzyme in these Basenjis had abnormal kinetic properties and was thermolabile. An antibody against R-type pk, the regular erythrocyte pk form, did not neutralize the pk activity of affected Basenjis, and results of electrophoretic studies suggested the expression of M2-type pk, a leukocyte and fetal erythroid pk-type. Clinically healthy heterozygous Basenjis had half-normal R-type pk activity and did not express the M2-type in their erythrocytes.

We conclude that severe chronic hemolytic anemia, caused by erythrocyte pk deficiency, and associated ostersclerosis still develop in Basenjis. A definitive diagnosis cannot be reached by simply measuring erythrocyte pk activity; rather, diagnosis requires measurement of glycolytic substrate accumulation and enzyme stability and immunologic or electrophoretic studies of erythrocyte pk.

Free access
in Journal of the American Veterinary Medical Association

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)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare the ease of use and accuracy of 5 feline AB blood-typing methods: card agglutination (CARD), immunochromatographic cartridge (CHROM), gel-based (GEL), and conventional slide (SLIDE) and tube (TUBE) agglutination assays.

Sample Population—490 anticoagulated blood samples from sick and healthy cats submitted to the Transfusion or Clinical Laboratory at the Veterinary Hospital of the University of Pennsylvania.

Procedures—Sample selection was purposely biased toward those from anemic, type B, or type AB cats or those with autoagglutination. All blood samples were tested by use of GEL, SLIDE, and TUBE methods. Fifty-eight samples were also tested by use of CARD and CHROM methods. The presence of alloantibodies in all cats expressing the B antigen as detected by use of any method was also assessed.

Results—Compared with the historical gold-standard TUBE method, good to excellent agreement was achieved with the other typing tests: CARD, 53 of 58 (91% agreement); CHROM, 55 of 58 (95%); GEL, 487 of 490 (99%); and SLIDE, 482 of 487 (99%; 3 samples were excluded because of autoagglutination). Four of the samples with discordant test results originated from cats with FeLV-related anemia.

Conclusions and Clinical Relevance—Current laboratory and in-clinic methods provide simple and accurate typing for the feline AB blood group system with few discrepancies. Retyping after in-clinic typing with the GEL or TUBE laboratory methods is recommended to confirm any type B or AB cats.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare canine blood-typing results determined by use of the card (CARD), gel (GEL), Michigan State University (MSU), and tube (TUBE) tests.

Sample Population—Blood samples from 23 healthy dogs.

Procedures—Blood samples anticoagulated with EDTA were screened by use of each blood-typing method according to manufacturers' protocols.

Results—Strong RBC agglutination reactions were observed with dog erythrocyte antigen (DEA) 1.1 reagents of the CARD and GEL tests as well as MSU test (only after adding Coombs' reagent) in 9 blood samples. By use of the CARD test, RBCs from 4 additional dogs agglutinated weakly; on the basis of MSU test results, these 4 dogs were classified as DEA 1.2 positive. All blood samples agglutinated with the B antigen reagent of the TUBE test. All but 2 blood samples had strong positive reactions with the DEA 4 reagent of the MSU test. All but 3 blood samples reacted with the E antigen reagent of the TUBE test. Three blood samples agglutinated with the DEA 3 reagent of the MSU test and A antigen reagent of the TUBE test. Five blood samples had strong agglutination reactions with the DEA 5 reagent of the MSU test.

Conclusions and Clinical Relevance—Use of the CARD test allows for rapid identification of DEA 1.1 but may produce weak reactions with blood from DEA 1.2-positive dogs. The GEL test is a reliable and rapid clinical laboratory method for identification of DEA 1.1. The MSU test requires Coombs' reagent for identification of DEA 1.1 and 1.2. (Am J Vet Res 2005;66:1386–1392)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare feline blood-typing results determined by use of the card (CARD), gel (GEL), tube (TUBE), University of Pennsylvania (Penn) tube, and Penn slide tests.

Sample Population—Blood samples from 38 healthy cats.

Procedure—Blood samples, anticoagulated with EDTA, were screened by use of each blood-typing method according to manufacturers' protocols.

Results—On the basis of the standard Penn tube and slide test results, 20, 11, and 7 cats were classified as type A positive, type B positive, and type AB positive, respectively. The same results were obtained with the anti-B and anti-B reagents of the TUBE test. Use of anti-A antibodies of original polyclonal and current monoclonal CARD tests resulted in mostly 2+ to 3+ (scale, 0 to 4+) agglutination reactions with blood samples from type A-positive cats; agglutination reactions with blood samples from type AB-positive cats were weak (1+). The anti-B lectin of the CARD test induced a 2+ to 4+ reaction with blood from all type B- and type AB-positive cats. Use of the GEL test allowed recognition of type A and type B blood samples; following addition of anti-A serum to control columns, type B blood was differentiated from type AB blood.

Conclusions and Clinical Relevance—Use of the inpractice CARD test allows identification of type A and type B-positive cats, but weak reactions of type AB blood with the anti-A monoclonal antibody raise concerns. The modified GEL and TUBE tests appear to be reliable clinical laboratory methods for feline blood typing. (Am J Vet Res 2005;66:1393–1399)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association