Effects of clopidogrel therapy on whole blood platelet aggregation, the Plateletworks® assay and coagulation parameters in cats with asymptomatic hypertrophic cardiomyopathy: a pilot study.

BACKGROUND: Although scientific evidence is limited, clopidogrel is frequently used as prophylaxis for arterial thromboembolism in cats with hypertrophic cardiomyopathy (HCM). OBJECTIVES: Evaluating effects of clopidogrel therapy in asymptomatic cats with HCM on (1) conventional whole blood aggregation (WBA), (2) alternative platelet aggregation assessed with tubes of the Plateletworks® assay and (3) standard coagulation parameters. ANIMALS AND METHODS: Prospective, randomized, double-blind, placebo-controlled pilot study. Fourteen asymptomatic HCM cats were randomly allocated to receive placebo (n = 5) or clopidogrel (18.75 mg/cat q24h, n = 9) as part of a larger study. Aggregation responses (to 20 µM adenosine diphosphate (ADP) and 10 µg/ml collagen) in WBA and the Plateletworks® assay and standard coagulation parameters were evaluated at baseline and after seven days of therapy. RESULTS: Clopidogrel therapy significantly reduced aggregation responses to ADP and collagen in the Plateletworks® agonists tubes (ADP and collagen: P < 0.001), but did not significantly reduce aggregation responses to ADP and collagen in the WBA technique (ADP: P = 0.07, collagen: P = 0.30). Clopidogrel therapy did not show a significant effect on prothrombin time, activated partial thromboplastin time, antithrombin, D-dimers and fibrinogen concentrations. CONCLUSION AND CLINICAL IMPORTANCE: Clopidogrel therapy at a dose of 18.75 mg/cat q24h for seven days causes a significant decrease in in vitro platelet aggregation evaluated with the Plateletworks® assay, without affecting standard coagulation parameters in cats with asymptomatic HCM.

Innocent Cardiac Murmur in Puppies: Prevalence, Correlation with Hematocrit, and Auscultation Characteristics.

BACKGROUND: The aims of this study were to establish the prevalence of innocent cardiac murmurs in clinically healthy puppies, to investigate a possible correlation between the presence of an innocent murmur and hematocrit, and to describe the auscultation characteristics of innocent murmurs. HYPOTHESIS: Lower hematocrit contributes to the genesis of innocent murmurs. ANIMALS: Five hundred and eighty-four client-owned clinically healthy puppies, between 20 and 108 days old. METHODS: Two cross-sectional surveys with a 1-year (n = 389 pups) pilot and a half-year (n = 195 pups) principal study periods. Cardiac auscultation was performed by a single, board-certified cardiologist. Hematocrit was measured with an automatized hematology analyzer. Echocardiography was performed only on puppies with a cardiac murmur in the principal study. RESULTS: In the pilot study, 15% of the dogs had a murmur. Innocent murmur was diagnosed in 28% of the 195 dogs in the principal study. Innocent murmurs were systolic, mostly with a musical character and with a maximal intensity of 2 of 6, and mostly with the point of maximal intensity in the left cardiac base. The hematocrit was significantly lower in the group with a murmur compared to the group without (P = .023). CONCLUSIONS AND CLINICAL IMPORTANCE: Innocent murmur was a common finding in puppies at the age when the first veterinary controls usually take place. Physiologic anemia contributes to the genesis of innocent murmurs in puppies. Rising hematocrit in growing puppies can explain the spontaneous disappearance of innocent murmurs with aging. Hematocrit did not differentiate innocent murmurs from abnormal murmurs.

Coagulation disorders in dogs with hepatic disease.

Liver disease has been associated with abnormalities in haemostasis. In this study, coagulation times, platelet counts, platelet activity parameters, activities of individual coagulation factors, D-dimers, antithrombin (AT) and protein C activity were measured in 42 dogs with histologically confirmed liver disease. Outcome was correlated with histological diagnosis. One or more coagulation abnormalities were present in 57% of dogs with hepatic disease. Activated partial thromboplastin time was significantly prolonged in dogs with chronic hepatitis (CH), with or without cirrhosis. Mean platelet numbers, AT and factor IX activity were significantly lower in dogs with CH plus cirrhosis, compared to dogs with other hepatopathies. D-dimers were not significantly increased in any group. Only three dogs, all with different histological diagnoses, satisfied the criteria for disseminated intravascular coagulation (DIC). Haemostatic abnormalities were primarily seen in dogs with cirrhosis and this may be due to reduced synthesis rather than increased consumption of coagulation factors.

Stability and reproducibility of ADVIA 120-measured red blood cell and platelet parameters in dogs, cats, and horses, and the use of reticulocyte haemoglobin content (CH(R)) in the diagnosis of iron deficiency.

Modern laser-based haematology analysers such as the ADVIA 120 have species-specific software and offer the possibility of assessing new haematological parameters. These parameters have yet to be evaluated, and as these analysers are often used in referral laboratories, it is important to know whether the values of haematological parameters change during sample transport. Therefore, samples of EDTA-anticoagulated blood from nine healthy dogs and EDTA- and citrate-anticoagulated blood from six healthy horses were collected and stored at room temperature for 72 and 48 hours, respectively. In canine samples, WBC and the red blood cell parameters Hb, Hb(cell), Ht, MCV, and MCHC changed significantly after only 24 hours of storage. Thus if canine blood samples need to be stored for 24 hours or longer, Hb, RBC, and MCH would appear to be more reliable parameters than Ht, Hb(cell), MCV, and MCHC. The cytoplasmic haemoglobin content (CH(R)) remained stable up to 48 hours. Both dog and horse platelet numbers were stable over time when blood was anticoagulated with EDTA. Of the platelet-derived parameters, MPC was already significantly lower 2 hours after collection of equine blood samples and was also significantly lower 24 hours after collection of canine blood samples. In contrast, MPV levels were significantly higher 48 hours after sample collection. Initial platelet numbers and platelet parameters were significantly different in citrate-anticoagulated blood and EDTA-anticoagulated blood, and platelet numbers and MPM decreased significantly in citrate-anticoagulated blood samples after only 4 hours of storage. After reference intervals for CH(R) had been established using samples from 53 non-anaemic dogs and 150 non-anaemic cats, the use of CH(R) to detect iron deficiency anaemia was tested in 63 dogs and 55 cats with different diseases. With the help of ROC curves, the optimal cut-off point was determined to be 1.22 fmol in dogs and 0.88 fmol in cats, resulting in a sensitivity of 95.2% and a specificity of 90.5% in dogs and 93.8% and 76.9% in cats, respectively.

[The hematologic analyzer Vet ABC: evaluation of its use for dogs and cats]. / De hematologische analyzer Vet ABC: evaluatie voor gebruik bij hond en kat.

The blood analyser Vet ABC was evaluated using the blood of dogs and cats. The correlation of results with those obtained with standard reference methods, reproducibility, and ease of operation were investigated. Good accuracy reproducibility were found in both species for leucocyte and erythrocyte counts, haematocrit, haemoglobin level, MCV, MCH, and MCHC. However, for some parameters new reference values will have to be established. The Vet ABC is not reliable for the measurement of platelets in the cat, and in the dog it does not give reproducible measurements of low numbers of platelets. In general, the Vet ABC is easy to use and does not need much maintenance.