Comparison of factor VIII:C and factor IX sensitivity of different commercial APTT reagents for canine plasma

In the present study, six commercial reagents for the determination of the activated partial thromboplastin time (APTT) were compared with respect to their factor VIII:C and factor IX sensitivity for measurements of canine plasma. For this purpose, plasma with different levels of factor VIII:C or factor XI activity (100, 80, 70, 60, 50, 40, 30, 20, 15, and 10% [factor VIII:C: additionally 5%]) was prepared by mixing pool plasma with plasma of dogs with haemophilia A or B. Double measurements of three different sample mixtures were carried out for each activity level. The sensitivity of the reagents was measured first based on the ratios of the coagulation time to the 100% values. In addition, the single factor activity (F VIII:C/IX(X0.975)), whose accompanying APTT corresponded to the upper limit of the reference range (97.5%-quantile, n = 50) of the respective reagent, was determined graphically. The APTT reflected a decrease of factor IX activity generally more sensitive than a reduction of factor IX activity of an identical degree. Based on ratios distant differences respecting factor VIII:C and factor IX sensitivity were found between different reagents using two way analysis of variance (p < 0.05). Significant differences between various reagents were also found with respect to the F VIII:C(X0.975) and the F IX(X0.975). These corresponded to values between 27 and 50% or 32 and 64%, respectively, dependent on the reagent. As a result, the more sensitive reagents fulfilled the demands on the sensitivity of APTT in humans. Based on the latter criterion the highest sensitivity for both factors was found for the same reagent (Pathromtin) consisting of kaolin as a contact activator and human placental phospholipid. Respecting all proofed reagents, however, no relation was found between contact activator and single factor sensitivity.     

Heparin in vitro sensitivity of the activated partial thromboplastin time in canine plasma depends on reagent.

The in vitro heparin sensitivity of 6 different commercial activated partial thromboplastin time (APTT) reagents was investigated based on artificial plasma samples prepared by addition of sodium heparin at different activities (0-1.5 IU/ml) to pooled normal canine plasma. Statistical analysis using 2-way analysis of variance was based on APTT ratios (APTT/mean APTT control). Significant differences between the APTT ratios of different APTT reagents (P < 0.00001) were found, which also depended on heparin activity (interaction between the factors; P < 0.00001). For example, mean APTT ratio at 0.7 IU/ml heparin varied between 1.2 and 2.5. The results of this study indicate that recommendations for the control of heparin therapy in dogs by APTT ratio should be reagent specific.     

The monitoring of heparin administration by screening tests in experimental dogs

The objective of this study was to investigate the relationship between different screening tests of haemostasis and amidolytic plasma activities of unfractionated (standard) heparin in dogs. Different doses of intravenous (i.v.) [25, 50 or 100 IU Kg(-1)bodyweight (BW)] and subcutaneous (s.c.) heparin (250, 500 and 750 IU kg(-1)) were given to groups each of five clinically healthy adult beagles. Measurements of heparin activity with a factor Xa-dependent chromogenic substrate, activated partial thromboplastin time (APTT) (two different reagents), thrombin time (TT, two different thrombin activities in the reagent: 3 and 6 IU ml(-1)) and the reaction time of the resonance thrombogram (RTG -r) with two different measuring devices were performed at different times. The relationship between ratio values (actual/baseline values) of the coagulation tests and heparin activity was analysed based on regression analysis and correlation coefficient.The greatest alterations were seen for the TT([3 IU ml(-1)])and the RTG -r which were near or exceeded the upper limit of measuring range, if 25 IU kg(-1)BW heparin were given i.v. at heparin plasma levels of 0.54 +/- 0.13 IU ml(-1). These results show, that only APTT and TT measured with high thrombin activity assay appear suitable for guiding high dose heparin therapy in dogs. Averaged alterations of APTT ratio in canine plasma were less than those observed in people for similar plasma heparin levels, indicating that the guideline extrapolated from people for monitoring high dose heparin therapy using APTT may not be valid for use in dogs.After coagulation times had been converted into ratio values, based on regression analysis and Wilcoxon's test, differences of heparin sensitivity were found not only for TT measured with different thrombin activities but also for different APTT reagents (P < 0.001). The correlation between amidylotic antifactor Xa activity and ratio of coagulation times was only moderate and found to be lower for RTG -r (instrument 1: r(s)= 0.711; instrument 2: r(s)= 0.573) than for the other coagulation tests (r(s)= 0.822 to r(s)= 0.890). This indicates a considerable variability of the ratio values of the screening tests at defined heparin plasma activities. These results show, that blood coagulation tests in general are little or unsuitable for heparin antifactor-Xa activity control.     

Activated partial thromboplastin time as a screening test of minor or moderate coagulation factor deficiencies for canine plasma: sensitivity of different commercial reagents.

To determine the sensitivity for detection of coagulation factor deficiencies by commercial reagents for canine plasma, 5 commercial activated partial thromboplastin time (APTT) reagents with different types of contact activator and phospholipid of various origin were examined. Thirty canine plasma samples with minor or moderate deficiencies of coagualition factors that influence the APTT were examined. Significant differences were found for the sensitivity of various reagents, but no correlation was found with the type of contact activator. Following the test instructions provided by the manufacturers, the number of APTT results that were prolonged beyond the reference range varied between 20 and 30 (sensitivity = 0.67-1.00); the number of corresponding results using a standardized test protocol varied between 19 and 28 (sensitivity: 0.63-0.93). The most sensitive reagent contained kaolin as a contact activator and a human placental thromboplastin. The results of this study indicate that the APTT test optimized for human plasma is also a sensitive screening test of the intrinsic system of canine plasma, provided that a suitable reagent is used.     

The correlation between plasma anti-factor Xa activity and haemostatic tests in healthy dogs, following the administration of a low molecular weight heparin

The aim of the study was to examine how activated partial thromboplastin time (APTT, two different reagents), thrombin time (TT, thrombin activity in the reagent: 3 or 6 IU ml(-1)) and reaction time of the resonance thrombogram (RTG-r) in healthy dogs are influenced by low molecular weight heparin (LMWH). Three different LMWH doses were given subcutaneously or intravenously to groups, each of five healthy dogs. Mean plasma anti-FXa activities of 0.43, 0.88 and 1.86 anti-FXa IU ml(-1)were measured 2 min after intravenous injection of 25, 50 or 100 anti-FXa IU kg(-1). At this time, a dose-dependent increase of the coagulation times, above the baseline values (P < 0.05), was observed for all haemostatic tests. The significant prolongation of coagulation time lasted 10 minutes to 3 hours, and it was dependent on the test employed and LMWH dose. After subcutaneous LMWH injection of 50, 100 and 200 anti-FXa IU kg(-1), significant changes of the coagulation time above initial values were limited to the period around the time when maximum anti-FXa activities (0.23, 0.43 or 0.90 anti-FXa IU ml(-1)) were observed. For the tests which were less affected by the LMWH (APTT, TT([6 IU ml)(-1)(])), only small increases (< 4 seconds) were observed even after the highest subcutaneous LMWH dose. The correlation between plasma heparin activity and the relative alteration compared to the initial value (ratio), of the different coagulation tests was only moderate and considerably lower for RTG-r (r(s)= 0.526) than for the TT (r(s)= 0.711([6 IU ml(-1)]), r(s)= 0.780([3 IU ml(-1)])) and APTT (r(s)= 0.667([reagent 1]), r(s)= 0.727([reagent 2])). The low degree of prolongation, which was found particularly for the group tests APTT and TT([6 IU ml)(-1)]), reflects the low anti-thrombin activity of LMWH. The results indicate that measurement of anti-FXa activity with chromogenic substrates is the method of choice to control LMWH therapy in dogs, as is the case in humans. Copyright2000 Harcourt Publishers Ltd Copyright 2000 Harcourt Publishers Ltd.     

Sensitivity of different prothrombin time assays to factor VII deficiency in canine plasma

The factor VII sensitivity of prothrombin time (PT) in dogs was tested using five different PT reagents and a commercial PT variant. The five PT reagents were used according to manufacturers' instructions (standard test, PT([ST])) and also using a modified test instruction (modified test, PT([MT])). Plasma samples with defined factor VII levels (10-100%) were prepared by adding increasing quantities of canine factor VII deficient plasma to the pooled plasma of healthy dogs. Statistical comparison based on prothrombin time ratios (PTR = PT sample: PT measured for 100% factor VII activity level) revealed significant differences between different reagents for PT([ST]) and also for PT([MT]). Factor VII activity at which PT was prolonged to the upper limit of the reference values (FVII([X(0.975)])) was 16-39% (PT([ST])) and 23-35% (PT([MT])). Factor VII sensitivity measured by PTR and also by FVII([X(0.975)]) values, was higher in four of five PT reagents using PT([MT]) when compared with PT([ST]). The results of this study indicate the importance of selecting a sensitive reagent and method for PT measurement and for careful interpretation of PT test results using canine plasma.     

Preclinical studies for the use of the platelet function analyser PFA-100 with the collagen/ADP cartridge in dogs

In this study, the following three aspects of platelet function analyser were investigated in dogs, using a collagen/ADP cartridge: precision, influence of the cartridge batch and of the sample storage time. Closure time and total volume of blood flow until closure of the capillary were measured. Based on several series of 5 repeated measurements mean coefficients of variation were 5% (3-6%; closure time) or 3% (1-5%; total volume). Neither closure time, nor total volume showed significant differences (p > 0.05) when comparing the results of 6 different batches of the collagen/ADP cartridge. Closure time (p = 0.0211, analysis of variance) and total volume (p = 0.0310) were significantly influenced by storage time, based on the sample material of 6 healthy dogs which was stored for 24 hours. Shortening of the closure time and decrease of the total volume observed in the time interval 1-2 hours after blood collection was followed by a significant prolongation of closure time and increase of the total volume (p < 0.05) starting 8 hours after blood collection. This study shows sufficient reproducibility which is not affected by reagent batch number. The results of the studies on storage indicated nearly identical recommendations for storage time before measurement of canine (0.5-2 hours) and human (0.5-3 hours) sample material.     

Coagulation values in normal ferrets (Mustela putorius furo) using selected methods and reagents

Background: Accurate determination of commonly measured coagulation values would be useful in the diagnosis and management of coagulopathies in domestic ferrets (Mustela putorius furo). We are unaware of reports of coagulation times in this species. Objectives: The purpose of this study was to determine reference values for prothrombin time (PT), activated partial thromboplastin time (PTT), fibrinogen concentration, and antithrombin (AT) activity in ferrets using selected methods and reagents. Methods: Blood samples obtained from 18 clinically healthy ferrets were anticoagulated with 0.129 M sodium citrate in a ratio of 9 parts blood to 1 part anticoagulant. Plasma was collected and stored at -70 degrees C until analysis. PT and PTT were measured with a fibrometer and with an ACL 3000 automated system. PTT was measured with and without the addition of ellagic acid. Fibrinogen was assayed by a turbidimetric method. AT activity was determined using a chromogenic assay and pooled ferret plasma (100% activity). Differences in methods and reagents were evaluated using paired t tests. Results: PT was significantly longer using the fibrometer (12.3+/-0.3, 11.6-12.7 seconds) compared with the ACL (10.9+/-0.3, 10.6-11.6 seconds) (P<.01). PTT was not significantly different with the fibrometer (18.7+/-0.9, 17.5-21.1 seconds) vs the ACL (18.1+/-1.1, 16.5-20.5 seconds), but was significantly longer on both analyzers when ellagic acid was added (fibrometer 20.4+/-0.8, 18.9-22.3 seconds; ACL 20.0+/-1.0, 18.6-22.1 seconds) (P<.01). Fibrinogen concentration was 107.4+/-19.8 mg/dL (90.0-163.5 mg/dL), and AT activity was 96%+/-12.7% (69.3-115.3%). Conclusion: These coagulation results for healthy ferrets will be useful in the evaluation of ferrets with coagulopathies, provided similar reagents and methods are used.     

Artifactual Prolongation of the Activated Partial Thromboplastin Time Associated With Hemoconcentration in Dogs

An inappropriate blood-to-anticoagulant ratio can cause an artifactual prolongation of the activated partial thromboplastin time (APTT) and prothrombin time (PT). In a drug safety study in dogs, we observed a 4-to 5-second increase in the APTT from baseline coincident with increased hematocrit values (56% to 65%) secondary to drug-induced vomiting and diarrhea. The PT and platelet counts were unchanged, and there was no clinical evidence of bleeding associated with venipuncture. Although we were unable to sample the same dogs to investigate the possible effect of hemoconcentration on the prolonged APTT, the question was addressed by an in vitro study. The hematocrit value for citrated blood samples collected from healthy beagle dogs was increased by the addition of aliquots of red blood cell/plasma mixtures in vitro while maintaining a 9:1 blood-to-anticoagulant ratio. There was a 2-to 4-second prolongation of the APTT associated with hematocrit values of 55% to 61 %, but the PT was not prolonged. Adjustment of the blood-to-anticoagulant ratio corrected the prolongation. This study emphasizes the important relationship of the blood-to-anticoagulant ratio when measuring coagulation tests in hemoconcentrated samples.     

Comparison of various canine blood-typing methods

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.     

Measurement of prothrombin time (PT) and activated partial thromboplastin time (APTT) on canine citrated plasma samples following different storage conditions

Samples from 75 clinically ill dogs were utilised in the study. APTT and PT tests were performed immediately on fresh citrated plasma samples (Fresh). The remaining plasma was stored at -20 degrees C for less than 4 months (n=36 samples) or between 4 and 7 months (n=39 samples). In batches of five, frozen samples were thawed rapidly and APTT and PT tests were performed on the thawed samples immediately (0RT) and after storage at room temperature (23 degrees C, range: 22-25 degrees C) for 24h (24RT) and 48h (48RT). The median APTT value from the (0RT) samples was significantly longer than that obtained from fresh samples (15s vs. 13.2s) but the PT value was not statistically different (7.8s vs. 7.6s). The median APTT (15s) and PT (7.5s) results from the (24RT) samples were not statistically different to those from the (0RT) samples (APTT: 15s, PT: 7.6s) but both tests were significantly longer (APTT: 16.5s, PT: 9.2s) from the (48RT) samples. We concluded that long term batching and freezing of clinical samples at -20 degrees C is acceptable for measurement of PT but not of APTT. We demonstrated that APTT and PT results do not change following storage of samples at room temperature for 24h but storage for 48h may lead to statistically and clinically significant changes (values at least 25% higher than the high value of the laboratory's reference interval) in both clotting times.     

Investigations on blood coagulation in the green iguana (Iguana iguana)

The prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time, kaolin clotting time (KCT), dilute Russell's viper venom time (DRVVT) and reptilase time, as well as five different plasma fibrinogen assays [gravimetry, Jacobsson method (extinction at 280 nm), Millar method (heat precipitation), kinetic turbidometry, Clauss method] and resonance thrombography were performed in 26 clinically healthy green iguanas. All assays were carried out in comparison with pooled normal canine plasma. In iguana plasma, the PT [median (x0.50) = 453-831 s, dependent on the reagent], APTT (x0.50 = 170-242 s, dependent on the reagent), thrombin time (x0.50 = 118 - > 1000 s, dependent on thrombin activity), KCT (x0.50 = 274 s), DRVVT (x0.50 = 349 s) and reptilase time (all samples > 1000 s) were widely scattered at the limit of measurability. Only fibrinogen concentrations measured using the Jacobsson method (x0.50 = 4.40 g/l) correlated well (r = 0.91) with gravimetry (x0.50 = 4.22 g/l). The results of this study indicate a limited suitability and a confined diagnostic significance of the selected methods in the green iguana. This may be caused by the species specificity of certain components of the reagents used, as well as a less optimal test system, i.e. relationship of test reagent to clotting factor concentrations in iguana plasma.     

Increased pulmonary transit times in asymptomatic dogs with mitral regurgitation

Pulmonary transit time (PTT) normalized to heart rate (nPTT) is a measure of the pulmonary blood volume (PBV) to stroke volume ratio (PBV/SV). It is an index of cardiac performance. To determine the effect of compensated mitral regurgitation (CMR) and decompensated mitral regurgitation (DMR) caused by valvular endocardiosis on the index nPTT, we measured nPTT by first-pass radionuclide angiocardiography and ECG in 13 normal dogs, 18 dogs with CMR, and 13 dogs with DMR. PTT was measured as time between onset of appearance of activity at the pulmonary trunk and the left atrium. In the normal dogs, the relationship between PTT and mean R-R interval (mRR) was PTT = 4.08 x mRR + 0.15 (R2 = 0.71). Normal nPTT was 4.4 +/- 0.6 (SD) (range. 3.6-5.3). in CMR, 6.3 +/- 1.6 (SD) (range, 4.0-9.7). and in DMR, 11.9 +/- 3.4 (SD) (range, 8.0-18.8). The differences among all groups were significant. Heart rates were 110 +/- 22 bpm in normal dogs, 111 +/- 20 in dogs with CMR, and 144 +/- 18 in dogs with DMR (P < .001 for difference between DMR group and normal and CMR groups). Increased nPTT in CMR indicates preclinical heart pump dysfunction. Heart rate-normalized pulmonary transit times may be a useful index of heart function in mitral regurgitation.     

The plasma coagulation system of domestic cats

Haemostaseological investigations of the animals need improvement. Usual methods in human medicine have to be reconsidered with regard to their qualification for veterinary medicine. A standardization of methods and accurate haemostaseological characterization of the reagents used are necessary for an appropriate interpretation of the results and interlaboratory comparative studies. Results of global tests (ARZ, PTT, TZW, TZ, RZ) and determinations of activity of single blood clotting factors (I, II, V, VII-XII) in healthy cats are presented and discussed in view of the mentioned.     

Evaluation of the reproducibility and accuracy of pH-determining devices used to measure urine pH in dogs

OBJECTIVE: To evaluate the reproducibility and accuracy of 4 portable pH meters, a reagent strip, and pH paper for measuring urine pH in dogs. DESIGN: Prospective masked randomized study. SAMPLE POPULATION: 201 free-catch urine samples from 114 hospitalized dogs. PROCEDURES: Urine samples were divided into 2-mL aliquots. Measurements of urine pH were obtained by use of a laboratory benchtop pH meter, 4 portable pH meters, a urine reagent strip, and pH paper. The pH of each aliquot was measured within 4 hours of collection by an evaluator unaware of the aliquot's origin.To assess reproducibility, the coefficient of variation for each pH measurement device was calculated. To determine which device was most accurate, the degree of agreement among the different devices was assessed in comparison with the benchtop pH meter, which was considered the reference method. RESULTS: 3 of the 4 portable pH meters had nearly perfect agreement with the reference method. The reagent strip and pH paper had moderate to poor agreement with the reference method. CONCLUSIONS AND CLINICAL RELEVANCE: Urine pH measurements should be made by use of a portable or benchtop pH meter when accurate measurements are crucial for diagnosis or treatment. Reagent strips and pH papers are useful in obtaining pH approximations but are not recommended when accurate measurements of urine pH are required.     

Evaluation of secondary haemostasis in canine leishmaniasis

Secondary haemostasis was evaluated in 26 dogs with leishmaniasis and 10 normal dogs by measurements of modified one-stage prothrombin time (m-OSPT), activated partial thromboplastin time (APTT), thrombin time, fibrinogen concentration and fibrin degradation products. There were no significant differences between the groups in the m-OSPT, fibrinogen concentration, or levels of fibrin degradation products. The APTT was significantly (P = 0.006) longer in the infected dogs than in the control group, and in infected dogs with alanine aminotransferase (ALT) activities > 50 U/litre. There was a significant linear regression between ALT and APTT. Thrombin time was significantly (P = 0.003) longer in the infected dogs than in the normal dogs. There were no significant differences between the thrombin times of sick dogs with different levels of creatinine or activities of ALT, or between male and female dogs, whether diseased or normal.     

Pharmacokinetics and pharmacodynamics of a therapeutic dose of unfractionated heparin (200 U/kg) administered subcutaneously or intravenously to healthy dogs

BACKGROUND: Heparin treatment has been recommended for dogs in hypercoagulable states such as disseminated intravascular coagulation, however, potential benefits have to be balanced against the bleeding risk if overdosage occurs. A better understanding of the pharmacology of heparin and tests to monitor heparin therapy in dogs may help prevent therapeutic hazards. OBJECTIVES: The purpose of this study was to evaluate the effects of 200 U/kg of sodium unfractionated heparin (UFH) on coagulation times in dogs after intravenous (IV) and subcutaneous (SC) administration and to compare these effects with plasma heparin concentrations assessed by its antifactor Xa (aXa) activity. METHODS: 200 U/kg of UFH were administered IV and SC to 5 healthy adult Beagle dogs with a washout period of at least 3 days. Activated partial thromboplastin time (APTT), prothrombin time (PT), and plasma aXa activity were determined in serial blood samples. RESULTS: After IV injection, PT remained unchanged except for a slight increase in 1 dog; APTT was not measurable (>60 seconds) for 45-90 minutes, and then decreased gradually to baseline values between 150 and 240 minutes. High plasma heparin concentrations were observed (maximal concentration = 4.64 +/-1.4 aXa U/mL) and decreased according to a slightly concave-convex pattern on a semilogarithmic curve, but returned to baseline slightly more slowly (t240-t300 minutes) than did APTT. After SC administration, APTT was moderately prolonged (by a ratio of 1.55 +/-0.28 APTT t0, range 1.35-2.01) between 1 and 4 hours after administration. Plasma aXa activity reached a maximum of 0.56 +/-0.20 aXa U/mL (range 0.42-0.9 U/mL) after 132 +/-26.8 minutes; this lasted for 102 +/-26.8 minutes. Prolongation of APTTs of 120-160% corresponded to plasma heparin concentrations of 0.3-0.7 aXa U/mL. CONCLUSIONS: As in humans, the pharmacokinetics of UFH in dogs was nonlinear. Administration of 200 U/kg of UFH SC in healthy dogs resulted in sustained plasma heparin concentrations in accordance with human recommendations for thrombosis treatment or prevention, without excessively increased bleeding risks. In these conditions, APTT can be used as a surrogate to assess plasma heparin concentrations. These findings need to be confirmed in diseased animals.     

Changes in the blood coagulation profile after ovariohysterectomy in female dogs

This study investigated changes in the coagulation profile of 10 healthy female dogs subjected to ovariohysterectomy. Blood samples were collected three times--before, directly after and 24 h after surgery. Plasma samples were analyzed to determine thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen content, D-dimer content and antithrombin (AT) III activity. The results revealed post-operative haemostatic system disorders related to prolonged APTT, higher fibrinogen and D-dimer concentrations and lower levels of AT III activity.     

Glycosylated haemoglobin assay of canine blood samples

A method for assaying canine glycosylated haemoglobin was evaluated. The method is a turbidimetric inhibition immunoassay and the final reaction is bichromatically measured using a multichannel automatic analyser. Within-run coefficients of variation (2.07 to 4.46 per cent) were permissible, but between-run coefficients of variation (2.10 to 8.25 per cent) were slightly more elevated. The detection limit of this assay is 0.052 per cent. A sample dilution of 10 microliters of sample and 500 microliters of haemolysing reagent is recommended for routine analysis of canine blood samples. A normal reference interval of 1.39 +/- 0.70 per cent was obtained from the glycosylated haemoglobin analysis in 82 healthy dogs and no statistically significant differences in relation to age or gender were observed. Some changes in glycosylated haemoglobin concentrations were noted throughout the ovarian cycle, although differences between dogs were evident. Since this assay specifically measures the glycosylated haemoglobin content in canine blood samples, it could be very useful for monitoring diabetic dogs.     

Coagulation profiles in dogs with congenital portosystemic shunts before and after surgical attenuation

BACKGROUND: Serious postoperative hemorrhage has been reported in dogs after closure of congenital portosystemic shunts (CPS). HYPOTHESIS: In dogs with portosystemic shunting, low coagulation factor activity is responsible for coagulopathy, which can cause complications after surgery. ANIMALS: Thirty-four dogs with CPS and 39 healthy dogs. METHODS: In a prospective study, coagulation times, platelet count, and the activity of 8 coagulation factors were measured in dogs before and after surgical shunt attenuation and in 31 healthy dogs. The effect of abdominal surgery on hemostasis was determined at ovariectomy in 8 healthy dogs. RESULTS: Dogs with CPS had lower platelet counts, lower activity of factors II, V, VII, and X, and increased factor VIII and activated partial thromboplastin time (APTT) compared to healthy dogs. After surgical attenuation, dogs with CPS had decreased platelet counts and activity of factors I, II, V, VII, IX, X, and XI and a prolonged prothrombin time (PT). Ovariectomy resulted in decreased activity of factors VII and X. Six weeks after surgery, portosystemic shunting persisted in 9 of 30 dogs, with no improvement of hemostatic values. CPS dogs without shunting had improved coagulation times and increased activity of factors II, V, VII, and X. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with CPS have lower activity of clotting factors compared to healthy dogs, resulting in a prolonged APTT. Surgical attenuation of the shunt results in increased abnormalities in coagulation times and factors immediately after surgery. Hemostasis is normalized after complete recovery of shunting after attenuation, in contrast to dogs with persistent shunting.