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1.
The aim of the present study was to examine the influence of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) on the function of canine thrombocytes. This was performed by adding different concentrations of UFH or LMWH to platelet rich plasma (PRP) or blood of healthy dogs: 0.2, 0.5, 1, 2, 5, 10, 20, and 50 I.U./ml UFH or Anti-FXaU/ml LMWH, respectively (aggregation induced by thrombin additionally: 0.025, 0.05, and 0.1 I.U./ml UFH or Anti-FXaU/ml LMWH.) Platelet aggregation induced by ADP, collagen or thrombin with the BORN method (n = 11) as well as the in vitro bleeding time using the analyzer PFA-100 (n = 5) were examined. Additionally, a specific test assay for ADP induced platelet aggregation was performed which enabled an individual adjustment of the aggregation maximum at 30-40% in the control measurements (n = 6). The most prominent effect was noted in the platelet aggregation induced by thrombin. The aggregation maximum of the platelet aggregation induced by 1 I.U./ml thrombin (final concentration) was significantly lower in all of the testet UFH concentrations > or = 0.025 I.U./ml UFH in comparison to control measurements. If the aggregation was induced by 10 I.U./ml thrombin a significant reduction of the aggregation maximum was restricted to UFH concentrations > or = 0.5 I.U./ml. The addition of LMWH to canine PRP resulted in a distinct decrease (p < 0.01) of the maximum aggregation induced by 1 I.U./ml thrombin in concentrations > or = 0.2 Anti-FXaU/ml LMWH. A slight decrease of the maximum aggregation induced by collagen was only found for UFH at activities > or = 20 I.U./ml. No significant systematic influence could be demonstrated for LMWH on the aggregation induced by collagen as well as for LMWH and UFH on the platelet aggregation induced by ADP. Capillary in vitro bleeding time (closure time) was prolonged only after adding high concentrations of UFH (> or = 10 I.U./ml) and LMWH (> or = 50 Anti-FXaU/ml) to the sample material. The results document the unimportant influence of therapeutic levels of UFH and LMWH on platelet function in dogs. Therefore, the remarkable inhibition of the aggregation induced by thrombin reflects mainly the antithrombin effect.  相似文献   

2.
The platelet function analyser PFA-100 aspirates blood in vitro from a sample reservoir in disposable test cartridges through a microscopic aperture cut into a biologically active membrane at the end of a capillary. In different cartridges the membrane is coated with collagen and adenosine diphosphate (ADP) or collagen and epinephrine (adrenaline) inducing a platelet plug and closure of the aperture. The closure time and total volume of blood flow through the capillary until closure of its aperture were measured. The correlation between platelet count in samples of thrombocytopenic dogs and results of the collagen/ADP cartridge (closure time: r(S)=-0.579; total volume: r(S)=-0.549) was closer than between platelet count and capillary bleeding time. No significant correlation was observed between platelet count and the results obtained with the collagen/epinephrine cartridge. In addition, a higher sensitivity was obtained for the collagen/ADP cartridge. Injection of acetylsalicylic acid into healthy dogs significantly increased closure time and total volume of both types of cartridges (P<0.01). Two dogs with von Willebrand's disease had abnormal values. In contrast, coagulopathies did not significantly influence the results of the platelet function analyser (P>0.05). Despite adequate sensitivity of measurements using the collagen/ADP cartridge to assess quantitative and qualitative platelet disorders in dogs, the influence of haematocrit (P<0.0001) will limit the clinical application of the analyser.  相似文献   

3.
Using the Born method, based on light transmission in platelet rich plasma, the minimum effective concentration (threshold values) of several platelet agonists for inducing maximum platelet aggregation was determined in healthy dogs. The final concentrations of aggregation agonists were as follows: adenosine diphosphate (ADP) (0.5-50 micromol/L; n = 75 healthy dogs), collagen (0.5-20 mg/mL; n = 75), thrombin (0.1-5 IU/mL; n = 75), ristocetin (1-10 mg/mL; n = 10), and epinephrine (5-50 micromol/L; n = 10). Reference values for maximum aggregation with a lower limit of > 80% were achieved for agonist concentrations 25 micromol/L ADP (80-98%), > or = 10 microg/mL collagen (80-96%), and > or = 1 IU/mL thrombin (80-97%). None of the concentrations of epinephrine and ristocetin used in this study induced quantitative aggregation in the whole group of healthy dogs. We also studied platelet aggregation in 14 uraemic dogs using selected concentrations of aggregation agonists. Aggregation was significantly decreased in uraemic dogs using intermediate agonist concentrations, i.e., in the region of the threshold concentration. In contrast, maximum aggregation was increased in uraemic patients compared to reference values using low concentrations of all three agonists (ADP: 1 micromol/L, collagen: 1 microg/mL, and thrombin: 0.1, 0.2 IU/mL).  相似文献   

4.
A recently identified intrinsic platelet function defect in 2 Spitz dogs is described. Both affected dogs had a history of chronic intermittent bleeding primarily from the nasal, oral, and gastrointestinal mucosa. Platelet aggregation in response to adenosine diphosphate (ADP), collagen, and platelet activating factor (PAF) was absent; however, platelet shape change did occur. Platelets aggregated in response to gamma thrombin, although a delayed onset and a reduced velocity of aggregation were present. Platelet 14C-serotonin release was diminished in response to collagen and PAF. Glycoprotein Illa was detected on the surface of platelets by flow cytometry. Platelets were morphologically normal under light and electron microscopy. Two male Spitz dogs, related to one of the affected dogs, did not have a bleeding diathesis. Collagen-induced platelet aggregation, however, was diminished in these 2 dogs. This platelet defect most closely resembles the defect described in Basset hounds.  相似文献   

5.
Haemostatic alterations in dogs naturally infected by ehrlichiosis and/or leishmaniasis were studied. Platelet count, ADP and collagen-induced platelet aggregation, prothrombin time, activated partial thromboplastin time (APTT) and plasma fibrinogen concentration were measured. An evident reduction of platelet aggregation response was shown for Leishmania-Ehrlichia co-infected dogs where platelet aggregation was lower in comparison with control and leishmaniotic dogs (ADP and collagen, P < or = 0.01) and ehrlichiotic dogs (ADP 10 and 7.5 microm, P < or = 0.05). Moreover, a significant increase in APTT as well as a reduction of the albumin/globulin rate (A/G) for leishmaniotic and co-infected dogs versus control and ehrlichiotic dogs was detected. The hypothesis of a synergism between leishmaniosis and ehrlichiosis in altering platelet function by different pathways is discussed.  相似文献   

6.
The effect of antiplatelet antibody on in vitro platelet function was investigated in 15 dogs with immune-mediated thrombocytopenia (ITP). Platelet aggregation was assessed after addition of serum from healthy dogs (n = 5) or dogs with ITP (n = 15) to platelet-rich plasma from a healthy donor dog. The aggregation responses to adenosine diphosphate, thrombin, and collagen/epinephrine were measured as the maximum aggregation observed after 2 minutes. In 13 of 15 dogs with ITP, maximal aggregation was significantly inhibited in response to ADP, thrombin, or collagen/epinephrine. The slope of the aggregation curve was decreased after addition of serum from 9 of 15 patients. A polyclonal rabbit anti—dog platelet antiserum induced inhibition of aggregation with all 3 agonists.
Serum from control dogs neither inhibited nor activated platelet aggregation. Aggregation experiments were repeated with all 3 agonists after addition of patient immunoglobulin (lg)G or IgG from a healthy dog to platelet-rich plasma. The IgG fraction from 9 of 10 dogs with ITP suppressed platelet aggregation. The IgG fraction from polyclonal rabbit anti—dog platelet antiserum inhibited platelet aggregation with all agonists. These results suggest that many canine ITP patients have circulating antibodies that, in addition to causing platelet destruction, may cause platelet dysfunction.  相似文献   

7.
Twenty-six female beagles were used to evaluate the effects of intravenous and long-term subcutaneous administration of cephalothin, cefazolin, and cefmetazole on platelet function and the coagulation cascade. Platelet aggregation in response to an adenosine diphosphate (ADP) agonist, bleeding time, platelet count, platelet size, prothrombin time (PT), and activated partial thromboplastin times (aPTT) were evaluated before and 90 minutes after two intravenous doses (22 mg/kg) of cephalothin, cefazolin, and cefmetazole given at 90-minute intervals. Dogs given saline injections were used as controls. Platelet count, platelet size, PT, and aPTT were evaluated after 7 days of subcutaneous administration of saline, cefazolin, and cefmetazole (22 mg/kg every 8 hours). A significant decrease in platelet aggregation in response to ADP was detected 90 minutes after intravenous administration of cephalothin. Bleeding time was increased significantly 90 minutes after intravenous administration of cefmetazole. Platelet size was decreased significantly 24 hours after onset of the study in all animals, including controls. No significant changes in platelet count, platelet size, PT, or aPTT were detected after 7 days of subcutaneous administration. Cefazolin had no adverse effects on platelet aggregation in response to ADP, bleeding time, platelet count, platelet size, PT, or aPTT. Therefore, cefazolin should be considered as a perioperative antibiotic in dogs with conditions predisposing to hemostatic complications.  相似文献   

8.
The purpose of this study was to examine the influence of cyclic combination chemotherapy on primary haemostasis in dogs with malignant lymphoma. Seventeen dogs receiving cytostatic treatment for high-grade lymphoma were included in the study. The dogs were treated with a Madison–Wisconsin derived protocol, which included asparaginase, vincristine, doxorubicin and prednisolone. At different time points during the first 4 weeks of induction, platelet count, capillary bleeding time, analysis of the platelet function using the platelet function analyser PFA-100, and platelet aggregation by the Born-method were measured.The most obvious changes were found for median values of the platelet count, which increased significantly from 210,000/μL before induction to 349,000/μL during the second week of induction (P = 0.0010). Median platelet count subsequently decreased by the fourth week of treatment (Friedman-test: P < 0.0001). None of the parameters of platelet function (capillary bleeding time, automatic platelet function analysis, aggregation maximum) showed significant changes with time (P > 0.05, Friedman-test). The results did not suggest that significant platelet dysfunction was induced by the chemotherapeutic protocol used in the study.  相似文献   

9.
A 3‐year‐old, female Greater Swiss Mountain dog developed a hemoperitoneum following an exploratory laparotomy and ovariohysterectomy. Platelet count, PT, APTT, and plasma von Willebrand factor antigen concentration were within RIs. A buccal mucosal bleeding time (BMBT) was prolonged. Given the probability of a hereditary thrombopathia, the dog was administered desmopressin, fresh platelet transfusions, and aminocaproic acid to control hemorrhage. Subsequently, DNA testing for the P2Y12 receptor gene mutation identified the dog as being a heterozygote (carrier). Further platelet function testing was performed following complete recovery. Results of a repeat BMBT and a point‐of‐care screening test using the Platelet Function Analyzer‐100 (collagen/adenosine‐diphosphate [ADP] test cartridge) were within RIs. Flow cytometric studies demonstrated a marked reduction in fibrinogen binding to the dog's platelets in response to ADP ‐ adenosine diphosphate activation. Likewise, turbidimetric aggregometry revealed a complete absence of platelet aggregation in response to ADP. However, there were a normal aggregation response to the platelet agonist convulxin and a mild reduction in amplitude in response to γ‐thrombin. This is the first report of a dog heterozygous for the P2Y12 receptor gene mutation exhibiting a bleeding tendency and having evidence of impaired platelet function in vitro in response to ADP activation. Given that the mutant allele for the P2Y12 thrombopathia appears to be widespread in the Greater Swiss Mountain dog breed, veterinarians need to be aware that both homozygotes and heterozygotes for this platelet receptor mutation are at risk of developing life‐threatening bleeding following trauma or surgery.  相似文献   

10.
Objectives – To assess platelet function of a commercial dimethyl‐sulfoxide (DMSO)‐stabilized frozen platelet concentrate (PC) using turbidimetric aggregometry. Design – In vitro analysis. Setting – Research laboratory in a school of veterinary medicine. Animals – Five units of frozen PC in 6% DMSO were studied. Fresh platelet‐rich plasma (PRP), with and without 6% DMSO, from 6 healthy dogs were used as controls. Interventions – Turbidimetric platelet aggregation was measured after initiation of platelet aggregation by addition of adenosine diphosphate (ADP), collagen, or thrombin at concentrations of 30 μM, 20 μg/mL, and 0.5 U/mL, respectively. Measures were performed at thaw and repeated 2 hours after thaw for the frozen PC. Measurements and Main Results – Compared with PRP, the frozen PC showed decreased aggregation in response to thrombin (amplitude of 84% versus 25%, P=0.01), and collagen (amplitude of 13% versus 3%, P=0.05) but not ADP (6.5% versus 18%, P=0.2). Compared with frozen PC at thaw, the frozen PC at 2 hours after thaw showed decreased aggregation in response to thrombin, collagen, and ADP (P<0.05). There was no difference in aggregation between PRP in 6% DMSO and frozen PC. Conclusions – These in vitro data suggest there is a decrease in platelet response to agonists associated with the freeze‐thaw process in the commercially available 6% DMSO canine frozen PC.  相似文献   

11.
This paper describes the optimal conditions for simultaneous evaluation of platelet aggregation and secretion capacity in canine whole blood using a Whole Blood Lumi-Aggregometer (Chrono-Log Corporation, Havertown, Pensylvania). For this purpose, the potential influence of several parameters was investigated using collagen, adenosinediphosphate (ADP), arachidonic acid (AA) and thrombin as platelet agonists.Results indicate that optimal experimental conditions to obtain reliable results include: allowing blood samples to stand at room temperature 60 minutes after blood collection, analysing samples within 3 hours from time of collection, adjusting platelet numbers to a final concentration of 150 000 microl(-1)and mixing the sample with isotonic saline (1:1) before adding the platelet agonist. The use of different platelet agonists offers variable results: collagen (0.5, 1 and 5 microg ml(-1)) is suitable for simultaneous platelet aggregation and adenosintriphosphate (ATP) secretion measurements; 1 UI ml(-1)of thrombin induced maximum ATP secretion;AA (0.5 and 1 mM) and ADP (5, 10 and 25 microM) did not give consistent results.The method described in this study has important clinical applications since it allows easy and quick platelet function evaluation in pathologic states.  相似文献   

12.
Haemostatic alterations in dogs experimentally infected with Leishmania infantumwere studied before and after therapy with meglumine antimonate. Haemostatic function tests including platelet count, collagen-induced platelet aggregation, prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen determination, and serum fibrinogen/fibrin degradation products concentration were performed. In the course of infection and before treatment, moderate thrombocytopenia (P<0·00001) decreased collagen induced platelet aggregation (P=0·0003), prolonged thrombin time (P=0·0117) and increased fibrinogen/fibrin degradation products were observed. Statistically significant differences of plasma fibrinogen concentration, prothrombin time, and activated partial thromboplastin time were not encountered. Haemostatic parameters returned to normal values after therapy. The results indicate that Leishmania infection may impair haemostasis suggesting induction of disseminated intravascular coagulation (DIC), and that treating dogs in an early stage of infection may potentially avoid the possibility of developing an uncompensated DIC.  相似文献   

13.
BACKGROUND: Thrombocytopenia is the most common and consistent hematologic finding in patients with canine monocytic ehrlichiosis. Dogs that recover from the severe thrombocytopenia still show bleeding tendencies, which suggest that platelet dysfunction is present. OBJECTIVES: The purpose of this study was to determine the occurrence and duration of platelet dysfunction in dogs with ehrlichiosis and to assess whether dysfunction is related to thrombocytopenia. METHODS: Ten adult male and female mongrel dogs were used in the study; 7 were inoculated intravenously with whole blood containing Ehrlichia canis, and 3 were used as controls. Platelet aggregation (with collagen/epinephrine and adenosine diphosphate (ADP)/epinephrine) and platelet counts were evaluated weekly for 112 days. RESULTS: The infected group showed a decrease in platelet aggregation response to collagen/epinephrine and ADP/epinephrine on days 7, 14, 21, 28, and 35 (P <.05). Thrombocytopenia was observed in all infected animals from day 7 to 35 postinfection (P <.05). CONCLUSIONS: The tendency of dogs infected with E canis to bleed may be related not only to thrombocytopenia but also to platelet dysfunction associated with the disease.  相似文献   

14.
Whole blood platelet aggregation in dogs with liver disease   总被引：1，自引：0，他引：1  
Whole blood platelet aggregation was determined in response to collagen, arachidonic acid, and adenosine diphosphate in 20 dogs with liver disease and in 20 control dogs. Platelet aggregation in response to collagen and arachidonic acid was reduced in dogs with liver disease, compared with control dogs (P less than 0.05), whereas there was no significant difference in platelet response to adenosine diphosphate between the 2 groups of dogs. Adenosine diphosphate was found not to be a reliable aggregation agent for determination of whole blood platelet aggregation in dogs. Dogs whose platelets did not aggregate in response to collagen and/or arachidonic acid manifested bleeding tendencies that could be attributed to platelet dysfunction.  相似文献   

15.
Platelet aggregation to collagen, arachidonic acid and adenosine diphosphate was evaluated in six dogs using a whole blood electronic aggregometer. The six dogs were then given phenylbutazone orally according to four different dosage levels and durations of treatment. Aggregation responses were measured at established intervals of time following phenylbutazone administration. Data on untreated dogs indicated that arachidonic acid, at a final concentration of 50 micrograms/mL and collagen, at a final concentration of 5 micrograms/mL, were useful agents for studying whole blood platelet aggregation in the dog, but adenosine diphosphate, at a final concentration of 30 microM was not. The high single dose (900 mg) of phenylbutazone significantly inhibited platelet aggregation to arachidonic acid at 1.5,4,7 and 12 hours following administration. The results indicated that the whole blood electronic aggregometer was of limited value in detecting subtle changes in platelet aggregation. It was concluded, however, that the instrument is potentially useful as a rapid screening aid for detecting canine patients at high risk of platelet-related bleeding problems.  相似文献   

16.
This study evaluated the adverse effects of oral firocoxib in dogs. Six dogs (20.2+/-6.3 kg) were studied. Values for complete blood count (CBC), serum urea, creatinine, alanine transaminase, alanine phosphatase, gamma-glutamyl transferase, occult blood in feces, platelet aggregation, and buccal mucosal bleeding time were measured before and 7, 14, 21, and 29 days after SID treatment with firocoxib 5.3+/-0.34 mg/kg (FG) or lactose 1 mg/kg (LG) for 28 days, in a randomized crossover study. Gastrointestinal (GI) tract endoscopy was performed before treatment began and at 29 days. Lesions were scored from grade 0 to 6. Data were analyzed using anova and paired t-tests (P<0.05). None of the dogs presented adverse clinical effects. There were no significant changes in CBC, biochemical profiles within groups, or differences between groups. Pretreatment mean+/-SD bleeding time (LG, 70.7+/-32.1 sec; FG, 75.8+/-38.1 sec) and platelet aggregation (LG, 86.4+/-10.2%; FG, 85.6+/-9.2%) were not significantly different from readings at 29 days (LG, 95.2+/-25 sec; FG, 91.7+/-24 sec and LG, 73.2+/-15.1%; FG, 84+/-10.3%) nor the groups were different. None of the dogs had positive fecal occult blood tests, and endoscopic lesion scores were grade 0 both before treatment and at 29 days. Administration of firocoxib did not cause any adverse effects on GI, or hematological or serum biochemical variables and appears to have been well tolerated by dogs.  相似文献   

17.
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.  相似文献   

18.
Platelet Hyperfunction in Dogs With Malignancies   总被引：1，自引：1，他引：0  
In vitro platelet aggregometry was performed on whole blood samples from 59 dogs with malignancies and 24 control dogs. Three reagents were used for the aggregation studies: collagen, arachidonic acid, and adenosine diphos-phate (ADP). The parameters measured to evaluate response to collagen included delay in the aggregation response, slope of the aggregation curve, maximum aggregation, and adenosine triphosphate (ATP) secretion. The platelets of dogs with malignancies exhibited significantly ( P < .05) shorter delays in the aggregation response, higher maximum aggregation, and higher ATP secretion when compared to control dogs. For the weaker reagents, ADP and arachidonic acid, the lowest concentration resulting in aggregation was determined. Platelets of dogs with malignancies tended to aggregate in response to lower concentrations of ADP than did those of controls ( P < .05). The response of platelets to the concentrations of arachidonic acid employed in this study was poor, with few samples achieving measurable aggregation. The findings of this study suggest that dogs with malignancies have hyperaggregable platelets.  相似文献   

19.
Platelet number, mean platelet volume, and platelet function were evaluated in 34 clinically normal dogs and 28 heartworm-infected (HWI) dogs. Mean platelet numbers for dogs of the HWI group was not significantly lower than those for dogs of the control group (214,000 vs 254,000 cells/microliter); however, 6 (21%) HWI dogs had platelet numbers less than 150,000/microliter, compared with only 2 (6%) heartworm-negative dogs. The mean platelet volume was not significantly different (7.8 vs 7.7 fl) between the 2 groups of dogs. Mean platelet aggregation responses to intermediate and low concentrations of collagen (3.0 and 1.5 micrograms) and to high, intermediate, and low concentrations of ADP (25, 10, and 5 microM) were greater in dogs of the HWI group. Mean platelet 14C-serotonin release was also greater in HWI dogs in response to high concentration of ADP (25 microM) and to intermediate concentration of collagen (3.0 micrograms).  相似文献   

20.
OBJECTIVE: To evaluate s.c. administration of unfractionated heparin (UFH) in accordance with a dosing regimen for high-dose treatment in dogs. ANIMALS: 10 healthy adult Beagles. PROCEDURES: Two groups of dogs (5 dogs/group) were given 6 injections of heparin (500 units of UFH/kg of body weight, s.c.) at intervals of 8 (experiment 1) and 12 (experiment 2) hours. Blood samples were collected before and 4 hours after heparin injections to determine amidolytic heparin activity, activated partial thromboplastin time (APTT), thrombin time, antithrombin activity, platelet count, and Hct. RESULTS: For experiments 1 and 2, mean +/- SD heparin activities before (experiment 1, 1.32 +/- 0.20 U/ml; experiment 2, 0.69 +/- 0.174 U/ml) and 4 hours after the last heparin injection (experiment 1, 1.71 +/- 0.30 U/ml; experiment 2, 1.10 +/- 0.30 U/ml) were higher than values calculated for the regimen used in experiment 1. Results of the investigated thrombin time test system with low thrombin activity were frequently beyond the measurement range, even with UFH activities > or = 0.6 U/ml. Moreover, a severe decrease of antithrombin activity became evident during both experiments (eg, in experiment 2 from 95.6 +/- 4.8 to 59.2 +/- 6.6%). In each treatment group, 2 dogs developed hematomas. CONCLUSIONS AND CLINICAL RELEVANCE: Calculations of the course of heparin activity after a single injection do not result in a reliable dosing regimen for high-dose heparin treatment in dogs. High-dose treatment must be monitored for each dog. Thrombin time measured with low thrombin activity is unsuitable for this purpose.  相似文献   

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