Clinical bleeding diathesis, laboratory haemostatic aberrations and survival in dogs infected with Angiostrongylus vasorum: 180 cases (2005-2019)

OBJECTIVES

Bleeding diathesis is a complication in dogs infected with Angiostrongylus vasorum. This retrospective study investigated clinical and laboratory haemostatic differences in A. vasorum-positive dogs with and without signs of bleeding and impact of bleeding on survival.

MATERIALS AND METHODS

Demographics, type of clinical bleeding, haematocrit and a range of haemostatic tests, including thromboelastography and derived velocity curves were retrospectively registered from A. vasorum-positive dogs. All parameters were compared between dogs with and without signs of bleeding using univariable analyses. Binomial and multinomial regression models were applied to examine specific indicators in the bleeding dogs. P-values were false discovery rate adjusted, and adjusted P<0.05 was considered significant.

RESULTS

One hundred and eighty dogs entered the study, including 65 dogs (36.1%) presenting with bleeding diathesis. Different types of cutaneous and mucosal bleeding were the most common clinical findings. Twenty dogs presented with neurological signs associated with intracranial and intra-spinal bleeding. One hundred and thirty-seven dogs had haematological and/or haemostatic laboratory analyses performed. Haematocrit, platelet count, thromboelastographic angle, maximum amplitude, global clot strength, maximum rate of thrombin generation and total thrombin generation were decreased, while prothrombin time was prolonged in bleeding dogs. Survival rate of bleeding dogs was lower at hospital discharge (76.9%) and 1 month after diagnosis (66.0%) than in dogs without signs of bleeding (94.8% and 90.1% at discharge and at 1 month, respectively).

CLINICAL SIGNIFICANCE

Several haemostatic aberrations were detected in A. vasorum-positive dogs with bleeding diathesis. Bleeding was identified as an important negative prognostic indicator in A. vasorum-positive dogs.

Changes in cardiovascular risk factors in patients undergoing first time coronary revascularization from 2003–2020, A nationwide population study

Introduction

Current knowledge of cardiovascular risk factors is primarily based on older studies that may not reflect current populations. Monitoring risk factors may influence decisions about prevention and treatment of ischemic heart disease. We hypothesize that the prevalence of traditional risk factors in patients undergoing first-time coronary revascularization has changed over time.

Purpose

We examined the proportion of patients with traditional cardiovascular risk factors from year 2003–2020 in patients undergoing first-time coronary revascularization.

Methods

We identified all adults undergoing first-time coronary revascularization (percutaneous intervention and bypass grafting) from 2003–2020 using Danish nationwide registries. Risk factors were defined as either medical prescriptions or diagnosis prior to first-time revascularization. We calculated the proportion of individual risk factors per year with associated 95% CI, and calculated the trend using chi-squared test for trend in proportion.

Results

We identified 152,692 patients who underwent first-time coronary revascularization. 78.5% of the patients underwent percutaneous coronary intervention and 21.5% underwent coronary artery bypass grafting, 73.8% were male, mean age 65 (SD 11.5), and 67.9% had at least 1 risk factor at first-time revascularization.

Figure 1 shows the trends in risk factors from 2003 to 2020.

From 2003–2005 to 2018–2020, the proportion of patients with at least 1 risk factors changed from 70.9 to 64.0%, hypertension changed from 41.4 to 36.0%, hypercholesterolemia decreased from 47.6 to 43.6%, aspirin use decreased from 52.4 to 32.06%, diabetes increased from 11.7 to 15.8%, chronic kidney disease increased from 2.4 to 4.4%, and chronic obstructive pulmonary disease increased from 4.95 to 4.96% (p-value for trend &lt;0.001 for all risk factors, except chronic obstructive pulmonary disease (p-value 0.96)).

Conclusion

We assessed the temporal trends in coronary risk factors over a 17-year period in patients undergoing first-time coronary revascularization. We found a large decrease in the proportion of patients with any risk factor, hypertension, hypercholesterolemia, and aspirin use, and an increase in diabetes and chronic kidney disease. The proportion of patients with chronic obstructive pulmonary disease was unchanged.

Funding Acknowledgement

Type of funding sources: None.

Retrospective review of 27 European cases of fatal elephant endotheliotropic herpesvirus-haemorrhagic disease reveals evidence of disseminated intravascular coagulation

Elephant endotheliotropic herpesvirus haemorrhagic disease (EEHV-HD) is widely acknowledged as the most common cause of mortality in young Asian elephants (Elephas maximus) in captivity. The objective of the current study was to perform a blinded, retrospective pathology review of European EEHV-HD fatalities, constituting the largest systematic assessment of EEHV-HD pathology to date. Findings between viral genotypes were compared with the aim to investigate if disseminated intravascular coagulation (DIC) could be substantiated as a significant complicating factor, thereby increasing the understanding of disease pathophysiology. Immunohistochemical staining confirmed endothelial cell (EC) damage and the presence of EC intranuclear inclusion bodies, demonstrating a direct viral cytopathic effect. Microthrombi were observed in 63% of cases in several organs, including lungs, which, together with widespread haemorrhage and thrombocytopenia reported in EEHV-HD case reports, supports the presence of overt DIC as a serious haemostatic complication of active EEHV infection. Death was attributed to widespread vascular damage with multi-organ dysfunction, including severe acute myocardial haemorrhage and subsequent cardiac failure. Systemic inflammation observed in the absence of bacterial infection may be caused by cytokine release syndrome. Findings reinforce the necessity to investigate cytokine responses and haemostatic status during symptomatic and asymptomatic EEHV viraemia, to potentially support the use of anti-inflammatory treatment in conjunction with anti-viral therapy and cardiovascular support.

Sex-related differences in primary metastatic site in rectal cancer; associated with hemodynamic factors?

Background and purpose

We investigated how features relating to pelvic cavity anatomy and tumor hemodynamic factors may influence systemic failure in rectal cancer.

Materials and methods

Rectal cancer patients (207 women, 343 men), who had been prospectively enrolled onto six cohorts and given curative-intent therapy, were analyzed for the first metastatic event. In one of the cohorts, the diameter of the inferior mesenteric vein (IMV) was assessed on diagnostic abdominal computed tomography images (n = 113). Tumor volume (n = 193) and histologic response to neoadjuvant therapy (n = 445) were recorded from diagnostic magnetic resonance images and surgical specimens, respectively.

Results

More women than men developed lung metastasis (p = 0.037), while the opposite was the case for liver metastasis (p = 0.040). Wider IMV diameter correlated with larger tumor volume (r = 0.481, p < 0.001) and male sex (p < 0.001). Female sex was the only adverse prognostic factor for lung metastasis. When sex, tumor volume, and histologic response were taken into consideration, poor tumor response remained the only determinant for liver metastasis (p = 0.002).

Conclusions

In a diverse rectal cancer population given curative-intent treatment, women and men had different outcome with regard to the primary metastatic site. Tumor hemodynamic factors should be considered in rectal cancer risk stratification.

Abstract 1337: Circulating angiogenic factors predict metastatic liver progression in rectal cancer patients given curative-intent oxaliplatin-containing neoadjuvant therapy

Purpose: Systemic failure remains a challenge in rectal cancer. Our recent data from a prospective study of intensified treatment in locally advanced rectal cancer indicated that neoadjuvant chemotherapy (NACT) and sequential long-course chemoradiotherapy (CRT), both modalities containing oxaliplatin, may have eradicated hypoxic tumor components and promoted an immune response that favored survival without metastatic progression. Because a tumor microenvironment with aberrant vasculature and hypoxia provokes immune tolerance, which is frequently connected to systemic inflammation, we hypothesized that circulating angiogenic factors may predict development of metastatic disease in rectal cancer patients given curative-intent treatment. Recognizing that angiopoietin 2 (ANGPT2) disrupts vascular remodeling by inducing endothelial cell apoptosis, we analyzed the soluble ANGPT2 and its endothelial receptor TEK at diagnosis and their linkage to inflammatory factors and progression-free survival (PFS).

Experimental procedures: We used clinical data from 275 rectal cancer patients prospectively enrolled onto three studies. In two of the studies, patients were referred either directly to pelvic surgery or to standard CRT (without oxaliplatin) or short-course radiotherapy before surgery. In the third, introduced above, 80 patients received oxaliplatin-based therapy (two cycles of NACT followed by CRT) before resection. PFS was defined as time from study enrolment until the first metastatic event or up to five years after surgery in the case of no event. Serum ANGPT2 and TEK were measured by immunoassays. The measures (range of 1.60-8.16 ng/ml for ANGPT2 and 1.42-2.97 ng/ml for TEK) were normalized according to each intracohort mean value to enable analysis of pooled samples. Statistical methods were Pearson product correlation and Cox regression.

Results: A correlation was seen between ANGPT2 and TEK levels (r = 0.34, p &lt; 0.001), and each factor correlated with C-reactive protein (for ANGPT2: r = 0.29, p &lt; 0.01; for TEK: r = 0.19, p &lt; 0.01). The higher ANGPT2 or TEK, the higher risk of developing liver metastasis (for ANGPT2: hazard ratio 1.01, p = 0.002; for TEK: hazard ratio 1.01, p = 0.039) in the oxaliplatin-exposed cohort. No such association was found for patients given treatment devoid of oxaliplatin.

Conclusions: High circulating ANGPT2 and TEK at diagnosis were associated with systemic inflammation and metastatic progression to the liver in rectal cancer patients receiving oxaliplatin-containing neoadjuvant therapy. Since we have previously shown that oxaliplatin may have breached the immune tolerance in patients with favorable outcome, there is a rationale for adding an anti-angiogenic agent in patients with hypoxic tumors as reflected by elevated circulating angiogenic factors.

Citation Format: Sebastian Meltzer, Kathrine Røe Redalen, Svein Dueland, Annette Torgunrud Kristensen, Arne Mide Solbakken, Kjersti Flatmark, Anne Hansen Ree. Circulating angiogenic factors predict metastatic liver progression in rectal cancer patients given curative-intent oxaliplatin-containing neoadjuvant therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1337.

Liposome-encapsulated chemotherapy: Current evidence for its use in companion animals

Cytotoxic drugs encapsulated into liposomes were originally designed to increase the anticancer response, while minimizing off-target adverse effects. The first liposomal chemotherapeutic drug was approved for use in humans more than 20 years ago, and the first publication regarding its use in a canine cancer patient was published shortly thereafter. Regardless, no general application for liposomal cytotoxic drugs has been established in veterinary oncology till now. Due to the popularity of canines as experimental models for pharmacokinetic analyses and toxicity studies, multiple publications exist describing various liposomal drugs in healthy dogs. Also, some evidence for its use in veterinary cancer patients exists, especially in canine lymphoma, canine splenic hemangiosarcoma and feline soft tissue sarcoma, however, the results have not been overwhelming. Reasons for this may be related to inherent issues with the enhanced permeability and retention effect, the tumour phenomenon which liposomal drugs exploit. This effect seems very heterogeneously distributed in the tumour. Also, it is potentially not as ubiquitously occurring as once thought, and it may prove important to select patients for liposomal therapy on an individual, non-histology-oriented, basis. Concurrently, new developments with active-release modified liposomes in experimental models and humans will likely be relevant for veterinary patients as well, and holds the potential to improve the therapeutic response. It, however, does not resolve the other challenges that liposomal chemotherapy faces, and more work still needs to be done to determine which veterinary patients may benefit the most from liposomal chemotherapy.

Is detection of intraperitoneal exfoliated tumor cells after surgical resection of rectal cancer a prognostic factor of survival?

Background

The prognostic significance of free cancer cells detected in peritoneal fluid at the time of rectal surgery remains unclear. A substantial number of patients will develop metastatic disease even with successful local treatment. This prospective non-randomized study investigated the prognostic value of intraperitoneal free cancer cells harvested in peritoneal lavage after surgery for rectal cancer. Mutational hotspots in mitochondrial DNA were examined as potential molecular signatures to detect circulating intraperitoneal free cancer cells when present in primary tumor and in lavage.

Methods

Point mutations in mitochondrial DNA amplifications were determined in primary tumors and corresponding exfoliated intraperitoneal free cancer cells in lavage from 191 patients with locally advanced rectal cancer scheduled for radical treatment. Mitochondrial DNA target sequences were amplified by polymerase chain reaction and base substitutions were detected by denaturant, cycling temperature capillary electrophoresis. Detection of intraperitoneal free cancer cells was correlated to survival.

Results

Of 191patients analyzed, 138 (72%) were identified with somatic mitochondrial point mutations in rectal cancer tumors. From this fraction, 45 patients (33%) had positive lavage fluid with corresponding somatic mtDNA point mutations in lavage representing circulating intraperitoneal free cancer cells. There was no significant survival difference between patients identified with or without somatic mitochondrial DNA point mutations in the corresponding lavage.

Conclusion

Somatic mitochondrial DNA point mutations identified in primary rectal tumors enable detection of circulating intraperitoneal free cancer cells in lavage fluid.

Intraperitoneal free cancer cells harvested from lavage immediately after surgery for rectal cancer does not represent an independent prognostic factor on survival.

Novel, high incidence exercise-induced muscle bleeding model in hemophilia B mice: rationale, development and prophylactic intervention

INTRODUCTION

Muscle hematomas are the second most common complication of hemophilia and insufficient treatment may result in serious and even life-threatening complications. Hemophilic dogs and rats do experience spontaneous muscle bleeding, but currently, no experimental animal model is available specifically investigating spontaneous muscle bleeds in a hemophilic setting.

AIM

The objective of this study was to develop a model of spontaneous muscle bleeds in hemophilia B mice. We hypothesized that treadmill exercise would induce muscle bleeds in hemophilia B mice but not in normal non-hemophilic mice and that treatment with recombinant factor IX (rFIX) before treadmill exercise could prevent the occurrence of pathology.

METHODS

A total of 203 mice (123 F9-KO and 80 C57BL/6NTac) were included in three separate studies: (i) the model implementation study investigating the bleeding pattern in hemophilia B mice after treadmill exercise; (ii) a study evaluating the pharmacokinetics of recombinant FIX (rFIX) in hemophilia B mice and based on these data; (iii) the treatment study, which tested therapeutic intervention with rFIX. At termination of the treadmill studies the presence of bleeds was evaluated.

RESULTS

Treadmill exercise resulted in a high incidence of muscle bleeds in F9-KO mice but not in C57BL/6NTac mice. Treating hemophilia B mice with rFIX before treadmill exercise prevented muscle bleeds.

CONCLUSION

A novel model of muscle bleeds in hemophilia B mice, responsive to rFIX, has been developed.

Selection of suitable reference genes for normalization of genes of interest in canine soft tissue sarcomas using quantitative real-time polymerase chain reaction

Quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) is a sensitive technique for quantifying gene expression. Stably expressed reference genes are necessary for normalization of RT-qPCR data. Only a few articles have been published on reference genes in canine tumours. The objective of this study was to demonstrate how to identify suitable reference genes for normalization of genes of interest in canine soft tissue sarcomas using RT-qPCR. Primer pairs for 17 potential reference genes were designed and tested in archival tumour biopsies from six dogs. The geNorm algorithm was used to analyse the most suitable reference genes. Eight potential reference genes were excluded from this final analysis because of their dissociation curves. β-Glucuronidase (GUSB) and proteasome subunit, beta type, 6 (PSMB6) were most stably expressed with an M value of 0.154 and a CV of 0.053 describing their average stability. We suggest that choice of reference genes should be based on specific testing in every new experimental set-up.

Expression of tissue factor in canine mammary tumours and correlation with grade, stage and markers of haemostasis and inflammation

Tissue factor (TF) expression in human cancers has been associated with a procoagulant state and facilitation of metastasis. This study was conducted in order to evaluate if TF was expressed in canine mammary tumours. Forty epithelial mammary tumours from 28 dogs were included. TF expression of the tumours was evaluated by immunohistochemistry using a polyclonal antibody against recombinant canine TF. In addition, thromboelastography, haemostatic and inflammatory parameters were evaluated in the patients. TF was recognized in 44% of benign and 58% of malignant tumours. TF localized to the cytoplasmic membrane of neoplastic luminal epithelial cells and/or diffusely in the cytoplasm. No association was found between TF expression and stage or grade of disease. A significant association between TF expression and antithrombin and plasminogen was found, and extensive TF expression was seen in a lymph node metastasis classified as anaplastic mammary carcinoma from a dog with concomitant disseminated intravascular coagulation (DIC).

Buprenorphine does not impact the inflammatory response in haemophilia A mice with experimentally-induced haemarthrosis

Haemarthrosis is the most common clinical manifestation of haemophilia and is responsible for significant morbidity in haemophilic patients. The murine experimentally-induced knee bleeding model is an important model in haemophilia research but it is currently unknown if the use of analgesia in this model might impact on the inflammatory response. The aim was to investigate the inflammatory response after a needle induced knee bleed in haemophilia A mice treated with buprenorphine or saline. One hundred and sixty mice were randomized into two groups to blindly receive buprenorphine or saline. All the mice were anaesthetized and knee injury was induced by inserting a 30 G needle into the right knee joint. At t = 6, 24, 48 and 72 h, 20 mice from each group were terminated and the following parameters were assessed: change in body weight and joint diameter, visual bleeding score (VBS), white blood counts, haematocrit, platelet concentrations, haemoglobin, plasma haptoglobin and plasma and synovial fluid levels of 23 cytokines. Twenty mice were terminated at t = 0 receiving no injury or treatment to provide baseline measures. Twenty-one cytokines in plasma and 22 cytokines in synovial fluid, joint diameter change, VBS and blood parameters were not significantly altered by the administration of buprenorphine. Slight alterations of plasma haptoglobin at t = 48 h, body weight, plasma and synovial eotaxin and plasma G-CSF were found in buprenorphine-treated mice. We demonstrated that buprenorphine does not overall impact on the inflammatory response, and the use of buprenorphine in the knee bleeding model in haemophilic mice should be continued.

Evaluation of hemostatic abnormalities in canine spirocercosis and its association with systemic inflammation

BACKGROUND

Canine spirocercosis is caused by the nematode Spirocerca lupi and is characterized by esophageal fibro-inflammatory nodules that may undergo neoplastic transformation. No sensitive and specific laboratory assays other than histopathology have been reported to differentiate non-neoplastic from neoplastic disease.

HYPOTHESIS/OBJECTIVES

Dogs with spirocercosis will have evidence of hypercoagulability based on thromboelastography (TEG)-derived maximal amplitude (MA); increased MA will be correlated with increased acute phase protein (APP) concentrations (C-reactive protein [CRP] and fibrinogen); increased MA and APPs will be exacerbated with neoplastic spirocercosis.

ANIMALS

Thirty-nine client-owned dogs with naturally occurring spirocercosis and 15 sex-matched healthy controls.

METHODS

A prospective comparative study evaluating TEG, activated partial thromboplastin time, prothrombin time, antithrombin (AT) activity, platelet count and D-dimer concentration, and APPs of dogs with non-neoplastic (n = 24) and neoplastic (n = 15) spirocercosis compared to control dogs.

RESULTS

Median MA was significantly increased in the non-neoplastic group (P < .01) and neoplastic group (P < .01) compared to the controls. Both APPs were significantly increased in the neoplastic group compared to the non-neoplastic and control groups. MA was strongly correlated with fibrinogen (r = 0.85, P < .001) and CRP (r = 0.73, P < .001). An MA >76 mm provided 96% specificity and 73% sensitivity for differentiation of disease state.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine spirocercosis is associated with increased TEG variables, MA and α, and decreased AT activity, which may indicate a hypercoagulable state seemingly more severe with neoplastic transformation. MA was correlated with APP in dogs with spirocercosis and can be used as an adjunctive test to support the suspicion of neoplastic transformation.

Disseminated intravascular coagulation in a novel porcine model of severe Staphylococcus aureus sepsis fulfills human clinical criteria

Sepsis is a common and often fatal complication in human patients in intensive care units. Relevant and well characterized animal models of sepsis may provide valuable information on pathophysiological mechanisms and be a mean of testing new therapeutic strategies. Large animal models of Staphylococcus aureus sepsis are rare, even though S. aureus increasingly affects human patients. Sepsis changes the haemostatic balance and leads to endothelial cell (EC) activation, coagulopathy and, in severe cases, disseminated intravascular coagulation (DIC). The aim of this study was to characterize the haemostatic and vascular alterations in a novel porcine model of severe S. aureus sepsis, investigating whether the changes fulfill the human clinical criteria for DIC. Five pigs were inoculated intravenously with S. aureus and two control animals were sham-inoculated. Blood samples were collected for thromboelastography (TEG) and assessment of plasma-based haemostatic parameters. Tissue was collected for histopathology and reverse transcriptase quantitative real-time polymerase chain reaction for measurement of mRNA encoding EC markers. All infected animals developed DIC; including procoagulant activation represented by hypercoagulable TEG profiles and prolonged clotting time. Histologically, numerous pulmonary thrombi were present in one pig. Inhibitor consumption was represented by decreasing antithrombin levels in infected pigs. Hyaline globules were found in three infected pigs, confirming fibrinolytic activation. EC activation was identified by expression of von Willebrand factor in small vessels together with elevated mRNA encoding activated EC markers. Severe haemostatic and vascular changes fulfilling the human criteria for DIC were therefore seen in all infected pigs. A tendency towards uncompensated DIC was seen in two animals.

Tumor phosphatidylinositol-3-kinase signaling and development of metastatic disease in locally advanced rectal cancer

Background

Recognizing EGFR as key orchestrator of the metastatic process in colorectal cancer, but also the substantial heterogeneity of responses to anti-EGFR therapy, we examined the pattern of composite tumor kinase activities governed by EGFR-mediated signaling that might be implicated in development of metastatic disease.

Patients and Methods

Point mutations in KRAS, BRAF, and PIK3CA and ERBB2 amplification were determined in primary tumors from 63 patients with locally advanced rectal cancer scheduled for radical treatment. Using peptide arrays with tyrosine kinase substrates, ex vivo phosphopeptide profiles were generated from the same baseline tumor samples and correlated to metastasis-free survival.

Results

Unsupervised clustering analysis of the resulting phosphorylation of 102 array substrates defined two tumor classes, both consisting of cases with and without KRAS/BRAF mutations. The smaller cluster group of patients, with tumors generating high ex vivo phosphorylation of phosphatidylinositol-3-kinase-related substrates, had a particularly aggressive disease course, with almost a half of patients developing metastatic disease within one year of follow-up.

Conclusion

High phosphatidylinositol-3-kinase-mediated signaling activity of the primary tumor, rather than KRAS/BRAF mutation status, was identified as a hallmark of poor metastasis-free survival in patients with locally advanced rectal cancer undergoing radical treatment of the pelvic cavity.

The impact of Staphylococcus aureus concentration on the development of pulmonary lesions and cytokine expression after intravenous inoculation of pigs

Acute respiratory distress syndrome is a common complication in severe sepsis. In pigs, the lungs play an important role in clearing systemic bacterial infections due to pulmonary intravascular macrophages found specifically in pigs. However, this increases the exposure of the porcine lungs to pathogens and potential injury. The authors propose that increasing the concentration of the inoculum without changing the bacterial dose will lead to severe sepsis with pronounced pulmonary lesions. This could potentially create a risk of cytokine spillover to the circulation, leading to an increased systemic response. Eight Danish Landrace pigs, approximately 10 weeks old, were inoculated twice with a low or once with a high concentration of Staphylococcus aureus. Three pigs were sham-inoculated. The animals were grouped based on macro- and microscopic lung lesions. The mRNA expression of local pulmonary inflammatory markers was compared to protein levels of systemic inflammatory markers. The most severe pulmonary lesions were observed in animals receiving the high S. aureus concentration, indicating that severity of lesions is dependent on inoculum concentration rather than total numbers of bacteria. Furthermore, local mRNA expression of inflammatory cytokines appeared to be dependent on the magnitude and severity of tissue destruction, including the ability to confine the lesions. Increasing mRNA levels of serum amyloid A could be a confident marker of severity of pulmonary lesions. Since no correlation was observed between local and systemic levels of inflammatory cytokines, this finding could indicate an ability of the porcine lung to compartmentalize the local inflammatory response and thus restrict systemic contribution.

The presence of antiphospholipid antibodies in healthy Bernese Mountain Dogs

BACKGROUND

The role of antiphospholipid antibodies in the prolonged activated partial thromboplastin time (aPTT) previously identified in healthy Bernese Mountain Dogs remains unknown. In people, an isolated prolonged aPTT without evidence of bleeding might be because of a thrombophilic condition caused by antiphospholipid antibodies.

OBJECTIVE

To examine if prolonged aPTT in healthy Bernese Mountain Dogs is because of antiphospholipid antibodies.

ANIMALS

Twenty-two healthy Bernese Mountain Dogs and 10 healthy adult dogs of various breeds.

METHODS

Prospective case control study. Healthy Bernese Moutain Dogs were examined twice over 6 months. Dogs were investigated for the presence of lupus anticoagulants and anticardiolipin (aCL) antibodies by the use of multiple aPTT tests with low and high lupus anticoagulant sensitivities, a mixing study, and an ELISA test for aCL antibody optical density to detect solid phase antiphospholipid antibodies.

RESULTS

In all, 15 of 22 healthy Bernese Mountain Dogs were positive for lupus anticoagulants. The Bernese Mountain Dogs had markedly higher levels of aCL antibodies compared with the control dogs (P = .006). In all, 7 of 21 of the Bernese Mountain Dogs were positive for both lupus anticoagulants and aCL antibodies, whereas 4 of 21 Bernese Mountain Dogs were negative for both.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lupus anticoagulants and aCL antibodies could be the cause of prolonged aPTT in healthy Bernese Mountain Dogs. The importance of the antiphospholipid antibodies in the dogs remains unknown.

Pharmacokinetics, pharmacodynamics and safety of recombinant canine FVIIa in a study dosing one haemophilia A and one haemostatically normal dog

Recombinant human FVIIa (rhFVIIa) corrects the coagulopathy in hemophilia A and B as well as FVII deficiency. This is also the case in dogs until canine anti-human FVIIa antibodies develop (~2 weeks). Recombinant canine factor VIIa (rcFVIIa), successfully over-expressed by gene transfer in haemophilia dogs, has provided long-term haemostasis (>2 years). However, pharmacokinetics (PK), pharmacodynamics (PD) and safety of rcFVIIa after pharmacological administration have not been reported. We therefore wanted to explore the safety, PK and PD of rcFVIIa in dogs. A pilot study was set up to evaluate the safety as well as PK and PD of rcFVIIa after a single intravenous dose of 270 μg kg(-1) to one HA and one haemostatically normal dog and to directly compare rcFVIIa with rhFVIIa in these two dogs. Single doses of rcFVIIa and rhFVIIa were well tolerated. No adverse events were observed. Pharmacokinetic characteristics including half-life (FVIIa activity: 1.2-1.8 h; FVIIa antigen 2.8-3.7 h) and clearance were comparable for rcFVIIa and rhFVIIa. Kaolin-activated thromboelastography approached normal in the HA dog with the improvement being most pronounced after rcFVIIa. This study provided the first evidence that administering rcFVIIa intravenously is feasible, safe, well tolerated and efficacious in correcting the haemophilic coagulopathy in canine HA and that rcFVIIa exhibits pharmacokinetic characteristics comparable to rhFVIIa in haemophilic and haemostatically competent dogs. This strengthens the hypothesis that rcFVIIa can be administered to dogs to mimic the administration of rhFVIIa to humans.

Pharmacokinetics, pharmacodynamics and safety of recombinant canine FVIIa in a study dosing one haemophilia A and one haemostatically normal dog

Recombinant human FVIIa (rhFVIIa) corrects the coagulopathy in hemophilia A and B as well as FVII deficiency. This is also the case in dogs until canine anti-human FVIIa antibodies develop (~2 weeks). Recombinant canine factor VIIa (rcFVIIa), successfully over-expressed by gene transfer in haemophilia dogs, has provided long-term haemostasis (>2 years). However, pharmacokinetics (PK), pharmacodynamics (PD) and safety of rcFVIIa after pharmacological administration have not been reported. We therefore wanted to explore the safety, PK and PD of rcFVIIa in dogs. A pilot study was set up to evaluate the safety as well as PK and PD of rcFVIIa after a single intravenous dose of 270 μg kg(-1) to one HA and one haemostatically normal dog and to directly compare rcFVIIa with rhFVIIa in these two dogs. Single doses of rcFVIIa and rhFVIIa were well tolerated. No adverse events were observed. Pharmacokinetic characteristics including half-life (FVIIa activity: 1.2-1.8 h; FVIIa antigen 2.8-3.7 h) and clearance were comparable for rcFVIIa and rhFVIIa. Kaolin-activated thromboelastography approached normal in the HA dog with the improvement being most pronounced after rcFVIIa. This study provided the first evidence that administering rcFVIIa intravenously is feasible, safe, well tolerated and efficacious in correcting the haemophilic coagulopathy in canine HA and that rcFVIIa exhibits pharmacokinetic characteristics comparable to rhFVIIa in haemophilic and haemostatically competent dogs. This strengthens the hypothesis that rcFVIIa can be administered to dogs to mimic the administration of rhFVIIa to humans.

Hypoxia-inducible factors--regulation, role and comparative aspects in tumourigenesis

Hypoxia-inducible factors (HIFs) play a key role in the cellular response experienced in hypoxic tumours, mediating adaptive responses that allow hypoxic cells to survive in the hostile environment. Identification and understanding of tumour hypoxia and the influence on cellular processes carries important prognostic information and may help identify potential hypoxia circumventing and targeting strategies. This review summarizes current knowledge on HIF regulation and function in tumour cells and discusses the aspects of using companion animals as comparative spontaneous cancer models. Spontaneous tumours in companion animals hold a great research potential for the evaluation and understanding of tumour hypoxia and in the development of hypoxia-targeting therapeutics.

Characterization of canine coagulation factor VII and its complex formation with tissue factor: canine-human cross-species compatibility

BACKGROUND

Canine models have been good predictors of efficacy of hemophilia treatments, including recombinant human coagulation factor (F)VIIa (hFVIIa). However, canine FVIIa and tissue factor (TF) have remained incompletely characterized.

OBJECTIVE

 To explore canine-human cross-species FVIIa-TF compatibility in order to strengthen the predictive value of canine models in research on FVIIa and TF.

METHODS

Canine FVIIa (cFVIIa) and canine TF((1-217)) [cTF((1-217))] were produced by recombinant techniques, and canine-human cross-species FVIIa-TF interactions were characterized in vitro.

RESULTS

 Recombinant cFVIIa and soluble cTF((1-217)) were produced and purified to homogeneity. hFVIIa and cFVIIa bound with comparably high affinities to cTF((1-217)) (K(D)=6.0±0.7 nm and K(D)=6.0±0.3 nm, respectively) and to cell surface-expressed cTF (K(D)=8.4±0.4 nm and K(D)=7.2±1.2 nm, for (125) I-labeled hFVIIa and cFVII, respectively). In contrast, cFVIIa bound to human TF (hTF) with decreased affinity, both in solution and on cell surfaces. The decreased binding resulted in reduced activity of cFVIIa in functional assays with hTF((1-209)) . In direct comparison, cFVIIa was more active than hFVIIa, both in the absence and the presence of cognate TF.

CONCLUSION

The present finding that hFVIIa binds to cTF essentially as it does to hTF substantiates the hypothesis that human FVIIa-TF biology can be reliably recapitulated in canine models on administration of hFVIIa to dogs.

Malignant histiocytosis and other causes of death in Bernese mountain dogs in Denmark

To determine the causes of death in Bernese mountain dogs, to assess the prevalence of malignant histiocytosis in the Danish Bernese mountain dog population, and to assess whether a hereditary pattern for this disease exists, 756 questionnaires were sent to members of the Danish Bernese Mountain Dog Club requesting information regarding the life span and causes of death of their dogs. A response rate of 57.7 per cent was achieved, giving information for 812 dogs, of which 290 had died. The average life span was 7.1 years. The most prevalent causes of death were neoplasia (42.1 per cent), old age (10.3 per cent), kidney disease (6.9 per cent), infection (5.9 per cent), skeletal problems (5.2 per cent), heart disease (3.8 per cent) and behavioural causes (3.5 per cent). Thirteen dogs were diagnosed with malignant histiocytosis, 11 of which were genealogically related.

IL-1 beta, IL-6, KC and MCP-1 are elevated in synovial fluid from haemophilic mice with experimentally induced haemarthrosis

The hallmark of haemophilia is the joint morbidity resulting from haemarthrosis that accounts for the majority of the bleeds. The exact mechanisms underlying changes are not fully elucidated. Cytokines are speculated to be involved in the progression and in vitro studies have confirmed the presence of elevated levels of cytokines in synovial tissue and cartilage from patients with haemophilic synovitis. In this study, the presence of selected cytokines in synovial fluid from haemophilia A mice with experimentally induced haemarthroses treated with rFVIII, rFVIIa and an rFVIIa analogue were investigated. Ten cytokines previously shown to be involved in arthritic syndromes were evaluated. Interleukin (IL)-1 beta, IL-2, IL-4, IL-6, IL-10, IL-17, Tumor Necrosis Factor-alpha (TNF- alpha), keratinocyte-derived chemokine (KC), Regulated upon Activation, Normal T cell Expressed and Secreted (RANTES) and monocyte chemotactic protein-1 (MCP-1) were included. In this article, we demonstrate, for the first time, that bleeding in knee joints of haemophilia A mice resulted in correlated increased levels of the pro-inflammatory cytokines: IL-1 beta, IL-6, KC and the MCP-1 in synovial fluid. These results suggest an important role of MCP-1 in the recruitment of monocytes and furthermore that the inflamed synovium releases IL-1 beta, IL-6 and KC, which in turn might contribute to further progression of the inflammatory process.

Molecular detection (k-ras) of exfoliated tumour cells in the pelvis is a prognostic factor after resection of rectal cancer?

BACKGROUND

After total mesorectal excision (TME) for rectal cancer around 10% of patients develops local recurrences within the pelvis. One reason for recurrence might be spillage of cancer cells during surgery. This pilot study was conducted to investigate the incidence of remnant cancer cells in pelvic lavage after resection of rectal cancer. DNA from cells obtained by lavage, were analysed by denaturing capillary electrophoresis with respect to mutations in hotspots of the k-ras gene, which are frequently mutated in colorectal cancer.

RESULTS

Of the 237 rectal cancer patients analyzed, 19 had positive lavage fluid. There was a significant survival difference (p = 0.006) between patients with k-ras positive and negative lavage fluid.

CONCLUSION

Patients with k-ras mutated cells in the lavage immediately after surgery have a reduced life expectation. Detection of exfoliated cells in the abdominal cavity may be a useful diagnostic tool to improve the staging and eventually characterize patients who may benefit from aggressive multimodal treatment of rectal cancer.

Hemostatic effect of recombinant factor VIIa, NN1731 and recombinant factor VIII on needle-induced joint bleeding in hemophilia A mice

BACKGROUND

Hemophilia A is the most common serious bleeding disorder, and the hallmark of this disease is joint bleeding episodes. These result in hemophilic synovitis, an inflammatory and proliferative condition of the joint, which progresses into a chronic degenerative arthritis, hemophilic arthropathy.

METHODS

In this paper, we describe the effect of recombinant factor VIIa (rFVIIa), and an analogue NN1731 as well as rFVIII on needle-induced bleeding in hemophilia A mice.

CONCLUSIONS

Here we show a reducing effect of rFVIIa and NN1731 on bleeding induced in hemophilic mice, and we show that preventive treatment with rFVIII normalizes bleeding.

Thromboelastographic evaluation of hemostatic function in dogs with disseminated intravascular coagulation

BACKGROUND

There is considerable variation in the coagulation profile of dogs with disseminated intravascular coagulation (DIC), making it difficult to assess overall hemostatic function.

OBJECTIVES

To characterize the overall hemostatic state in dogs with DIC, by use of tissue factor-activated thromboelastography (TF-TEG), and to determine whether there is an association between hemostasis and outcome.

ANIMALS

50 dogs with DIC.

METHODS

Dogs admitted to the intensive care units, with an underlying disease known to predispose to DIC, were prospectively assessed with TF-TEG. Citrated blood samples were collected daily during hospitalization and an extended coagulation panel and TF-TEG were performed. Diagnosis of DIC was based on expert opinion.

RESULTS

Hemostatic dysfunction was observed on the TF-TEG profile in 33/50 of the dogs, of which 22/50 were hypercoagulable and 11/50 were hypocoagulable based on the TF-TEG G value alone. There were significant differences in k, alpha, and MA values (P < .0001) among hypo-, normo-, and hypercoagulable dogs. There was a significant difference in case fatality rate between hypo- (64%) and hypercoagulable (32%) dogs (relative risk = 2.38; P= .04). Dogs that died had significantly lower antithrombin activity (P= .03) and higher d-dimer concentration (P= .03) than survivors.

CONCLUSIONS

The most common overall hemostatic abnormality in dogs diagnosed with DIC was hypercoagulability, and there was significant difference in survival between hyper- and hypocoagulable dogs. The results suggest TF-TEG is valuable in the assessment of hemostatic function in dogs diagnosed with DIC.

Investigation of the thrombin-generating capacity, evaluated by thrombogram, and clot formation evaluated by thrombelastography of platelets stored in the blood bank for up to 7 days

BACKGROUND AND OBJECTIVES

Transfusion based on the Thrombelastograph (TEG) results reduces transfusion requirements in cardiac surgery and in liver transplantation. Taking the pivotal role of thrombin generation in the coagulation process into consideration, the clinical utility of the TEG may, in part, depend on its reflection of the dynamics of thrombin generation.

MATERIAL AND METHODS

The kinetics of thrombin generation of platelets stored for 2 and 7 days, respectively, was assessed by calibrated automated thrombogram (CAT) and the lag time (min), time to peak (ttPeak; min), peak (nm thrombin) and endogenous thrombin potential (ETP; nm thrombin*min) were registered. Clot formation was evaluated by TEG and the R time (min), maxial amplitude (MA; mm), time to maximum thrombus generation (TMG; min) and maximum thrombus generation (MTG; dynes cm(-2) s(-1)) and total thrombus generation (TTG; dyne cm(-2)) were registered.

RESULTS

Platelets become more procoagulant, evaluated both by TEG and CAT during storage. The reduction in CAT lag time and the ttPeak correlated with a decrease in the TEG R time and TMG (P < 0.0001) as did the CAT peak thrombin generation and the TEG MTG (P = 0.0035). No correlation between ETP and TTG was found (P = 0.65).

CONCLUSION

The kinetics of thrombin generation, as evaluated by CAT, correlates with the thrombus generation, as evaluated by thrombelastography and this may in part explain the clinical utility of the TEG in identifying clinically relevant coagulopathies, secondary to impaired thrombin generation.

In vivo models of haemophilia - status on current knowledge of clinical phenotypes and therapeutic interventions

Animal models have contributed immensely to the understanding of and the improvement in treatment of haemophilia A and B. First, establishment of haemophilic dog colonies provided an invaluable opportunity to investigate the diseases and later, the advances in gene technologies resulting in small haemophilic animal models were a milestone in the preclinical research making it possible to address some of the many unanswered questions. This review provides an overview of animal models used in the study of haemophilia as well as a short overview of the contributions resulting from studies in these models.

Efficacy and safety of imidacloprid/moxidectin spot-on solution and fenbendazole in the treatment of dogs naturally infected with Angiostrongylus vasorum (Baillet, 1866)

A randomized, blinded, controlled multicentre field trial study was conducted to evaluate the efficacy and safety of imidacloprid 10%/moxidectin 2.5% spot-on solution and fenbendazole in treating dogs naturally infected with Angiostrongylus vasorum. Dogs were randomly treated either with a single dose of 0.1 ml/kg bodyweight of imidacloprid 10%/moxidectin 2.5% spot-on solution or with 25 mg/kg bodyweight fenbendazole per os for 20 days. The study period was 42 days with dogs being examined on days 0, 7 and 42. The primary efficacy parameter was the presence of L1 larvae in faecal samples evaluated by a Baermann test from three consecutive days. Thoracic radiographs performed on each visit were being taken as a paraclinical parameter to support the results of the Baermann test. Twenty-seven dogs in the imidacloprid/moxidectin group and 23 dogs in the fenbendazole group completed the study according to protocol. The efficacies of the two treatment protocols were 85.2% (imidacloprid/moxidectin) and 91.3% (fenbendazole) with no significant difference between treatment groups. On radiographic evaluation pulmonary parenchyma showed similar improvement in each group. No serious adverse effects to treatment were recorded: most of the minor adverse effects were gastrointestinal such as diarrhea (nine dogs), vomitus (eight dogs) and salivation (three dogs). In general, these adverse effects were of short duration (1-2 days) within the first few days after treatment start and required little or no treatment. This prospective study demonstrates that both treatment protocols used are efficacious under field conditions, that treatment of mildly to moderately infected dogs with either of these protocols is safe and yields an excellent prognosis for recovering from the infection.

Effects of breed, gender, exercise and white-coat effect on markers of endothelial function in dogs

This study examines how systemic biomarkers of endothelial function and nitric oxide metabolism are affected by exercise in dogs. Furthermore, breed variation and white-coat effect have been tested by sampling three different dog breeds both in their home and in a clinical setting. Short-term exercise increased plasma nitrate and nitrite (NOx) and von Willebrand factor (vWf). There was significant difference between Pointers and the small dog breeds Cairn Terriers and Cavalier King Charles Spaniels in the general plasma levels of vWf and asymmetric dimethylarginine (ADMA). NOx and vWf were significantly higher when the sample was taken in the laboratory cf. at home, whereas ADMA and L-arginine were significantly lower. In conclusion, both short-term exercise and white-coat effect influence several plasma markers of endothelial function depending also on the breed and gender of the dogs. These findings should be considered in future studies concerning endothelial function in dogs.

Cellular, hemostatic, and inflammatory parameters of the surgical stress response in pigs undergoing partial pericardectomy via open thoracotomy or thoracoscopy

BACKGROUND

Thoracoscopy has been shown to reduce the inflammatory and immunologic response to surgical stress, as compared with corresponding open procedures in humans. The influence on the hemostatic system, however, has not been thoroughly evaluated. The current study aimed to compare the perioperative and immediate postoperative changes in cellular, hemostatic, and inflammatory parameters after a partial pericardectomy performed by either thoracoscopy or thoracotomy.

METHODS

For this study, 16 pigs were randomly assigned to have a partial pericardectomy performed thoracoscopically or by thoracotomy. Blood was collected intraoperatively, then 10 min, 3 h, and 6 h after surgery. Whole ethylenediaminetetraacetic acid (EDTA)-stabilized blood and plasma were examined for cellular, hemostatic, and inflammatory parameters, respectively, and thromboelastography (TEG) was performed on citrated whole blood.

RESULTS

No significant difference in any of the parameters measured was found between the two groups except for the TEG parameter R-time, which was significantly shorter in the thoracoscopic group 3 h postoperatively. In both groups, a significant postoperative state of hypercoagulability and increase in inflammatory parameters was found. Additionally, pig blood showed a high degree of hypercoagulability in preoperative measurements, as compared with other species.

CONCLUSIONS

Partial pericardectomy performed by thoracotomy or thoracoscopy in pigs produces a surgical stress response of equal magnitude, as measured by cellular, hemostatic, and inflammatory changes.

Serum Fructosamine Concentrations in 59 Dogs Naturally Infected with Angiostrongylus vasorum

Retrospectively, 89 cases of dogs infected with Angiostrongylus vasorum were examined. Fifty-nine of these 89 dogs fulfilled the criteria of not being dually infected with Crenosoma vulpis as well as having a full biochemistry profile including serum fructosamine available. The mean serum fructosamine value of the 59 dogs was 236 micromol/l (reference value 258-348 micromol/l) and significantly lower than the serum fructosamine level of 314 micromol/l in a control group of 42 clinically healthy dogs. Eleven dogs were available for follow up after successful treatment of angiostrongylosis. In this group, the serum fructosamine value rose from a mean of 244 micromol/l to a mean of 320 micromol/l following treatment. Serum glucose, albumin and protein were all within the respective reference ranges at all sampling points. The results indicate that serum fructosamine could be affected by infection with A. vasorum. Furthermore, this change cannot be explained by measurable changes in the level of glucose, albumin or protein. The clinical impact of this study is that a low fructosamine value may indicate infection with A. vasorum thereby suggesting a Baermann test to be performed.

DNA variants in the ATM gene are not associated with sporadic rectal cancer in a Norwegian population-based study

BACKGROUND AND AIMS

A large number of DNA single-nucleotide polymorphisms (SNPs) have been discovered following the Human Genome Project. Several projects have been launched to find associations between SNPs and various disease cohorts. This study examined the possible association between the reported SNPs and sporadic rectal cancer. It has been proposed that SNPs in the ataxi-telangiectasia mutated (ATM) gene modulate the penetrance of some cancers. The investigated target sequence harbors three polymorphisms (IVS38-8 T/C in intron 38, 5557 G/A and 5558 A/T in exon 39), resulting in eight possible microhaplotypes at the DNA level. Furthermore, the two exonic SNPs are sited next to each other, allowing four possible amino acids in the same codon.

METHODS

We report on a new method analyzing SNPs and microhaplotypes based on theoretical thermodynamics and migration of variant fragments by cycling temperature capillary electrophoresis. Fluorophore-labeled PCR products were analyzed without any post-PCR steps on a standard 96 capillary-sequencing instrument under denaturing conditions.

RESULTS

More than 7000 alleles were microhaplotyped based on peak migration patterns of individual samples and sequencing results. The ATM polymorphisms and microhaplotypes examined did not significantly differ between sporadic rectal cancer and normal population.

CONCLUSION

No associations were found between the IVS38-8 T/C, 5557 G/A and 5558 A/T polymorphisms and microhaplotypes in the ATM gene with respect to sporadic rectal cancer.

Approach to analysis of single nucleotide polymorphisms by automated constant denaturant capillary electrophoresis

Melting gel techniques have proven to be amenable and powerful tools in point mutation and single nucleotide polymorphism (SNP) analysis. With the introduction of commercially available capillary electrophoresis instruments, a partly automated platform for denaturant capillary electrophoresis with potential for routine screening of selected target sequences has been established. The aim of this article is to demonstrate the use of automated constant denaturant capillary electrophoresis (ACDCE) in single nucleotide polymorphism analysis of various target sequences. Optimal analysis conditions for different single nucleotide polymorphisms on ACDCE are evaluated with the Poland algorithm. Laboratory procedures include only PCR and electrophoresis. For direct genotyping of individual SNPs, the samples are analyzed with an internal standard and the alleles are identified by co-migration of sample and standard peaks. In conclusion, SNPs suitable for melting gel analysis based on theoretical thermodynamics were separated by ACDCE under appropriate conditions. With this instrumentation (ABI 310 Genetic Analyzer), 48 samples could be analyzed without any intervention. Several institutions have capillary instrumentation in-house, thus making this SNP analysis method accessible to large groups of researchers without any need for instrument modification.

Evaluation of a commercially available enzyme-linked immunosorbent assay (ELISA) for the determination of C-reactive protein in canine serum

The purpose of this study was to evaluate a commercially available enzyme-linked immunosorbent assay for determination of canine serum C-reactive protein (CRP). The concentration of CRP could be determined accurately and the intra- and inter-assay coefficients of variation were in the range of 6.9-10.1 and 7.5-29.0%, respectively. This level of imprecision between runs is usually considered unacceptable for diagnostic purposes, but the overall results indicated that the assay was useful in differentiating dogs suffering from infections, from dogs suffering from various other diseases (neoplastic diseases, endocrine/metabolic disorders), and healthy dogs. The assay was also able to detect dynamic changes of CRP during development and after cessation of spontaneous occurring inflammatory stimuli in two clinical cases.

Intravenous magnesium does not influence the activity of the coagulation cascade

Experimental arterial thrombus formation is reduced during intravenous magnesium infusion. It is well documented that magnesium reduces platelet reactivity, but the antithrombotic effect could also originate from anticoagulant properties or increased fibrinolysis. We therefore evaluated the effect of intravenous magnesium on prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III complex (TAT) concentrations, and fibrin degradation products (FbDP) in a randomized, cross-over study in 14 healthy volunteers. Citrated blood samples were collected at 0, 30, and 180 min. An additional in vitro study on magnesium's effect on the activity of different coagulation factors was carried out. A transient increase was seen in F1 + 2 and TAT after 30 min but without any significant difference between the placebo and magnesium period. FbDP did not change significantly between the two treatments. Increasing concentrations of magnesium dose-dependently decreased binding of activated factor X to activated factor VII (FVIIa), but the decrease was slight and probably without any significance for coagulation at the concentrations tested. No effect was observed on the activity of FVIIa or activated factor VIII. In conclusion, no significant differences were observed on markers of coagulation or fibrinolytic activity during intravenous magnesium infusion. These results indicate that the observed antithrombotic effect of magnesium is more likely to arise from the previously observed platelet inhibition.

Increased platelet aggregation response in Cavalier King Charles Spaniels with mitral valve prolapse

Mitral valve prolapse (MVP) is a fundamental feature of myxomatous mitral valve disease in the dog. In humans, primary MVP is associated with increased platelet reactivity. In Cavalier King Charles Spaniels (CKCS), a breed predisposed to myxomatous mitral valve disease, there is a high prevalence of hypomagnesemia and platelet anomalies, such as thrombocytopenia and macrothrombocytosis. The objective of this study was to evaluate platelet aggregation responses in CKCS and to determine the relationship between the platelet aggregation response and serum magnesium concentration, MVP, mitral regurgitation (MR), and platelet count. In 19 CKCS with MVP and 7 control dogs (not CKCS), the platelet aggregation response to 3 different agonists was compared. The CKCS with >100,000 platelets/microL (n = 10) had a significantly higher maximum aggregation response with regard to all tested agonists than the CKCS with <100,000 platelets/microL (n = 9) and control dogs (n = 7). The CKCS with <100,000 platelets/microL had a platelet aggregation response similar to the control dogs. There was no correlation between degree of MVP and platelet aggregation response. Platelet diameter increased (P = .006) and serum magnesium concentration decreased (P = .04) with lower platelet concentration. In conclusion, CKCS with MVP appeared to separate into 2 groups--1 group with <100,000 platelets/microL, normal platelet aggregation, low serum magnesium concentration, and enlarged platelets, and another group with >100,000 platelets/microL, increased platelet aggregation, and normal serum magnesium concentration and platelet size.

Local application of FFR-rFVIIa reduces thrombus formation at arterial anastomosis in rats

Thrombosis is still a significant problem in microvascular surgery. The aim of this study was to evaluate the antithrombotic effect of topically applied active site-inhibited recombinant human factor VIIa (FFR-rFVIIa) in a rat model with microvascular thrombosis. Forty-five male rats were allocated to one of three groups: local treatment with vehicle only, local treatment with 0.035 mg of FFR-rFVIIa, or local treatment with 0.35 mg of FFR-rFVIIa. An arteriotomy was made in the right femoral artery. Ten minutes following topical application, a thrombogenic anastomosis was performed. Using a transilluminator, thrombus formation and anastomotic bleeding episodes were observed and registered for 40 min. Local application of FFR-rFVIIa resulted in a 85-90% reduction of thrombus formation in both treated groups compared to the control group, but the reduction was only statistically significant in the group treated with 0.035 mg of FFR-rFVIIa. An increased occurrence and duration of anastomotic bleeding episodes were observed in both FFR-rFVIIa-treated groups.

Local application of recombinant active-site inhibited human clotting factor VIIa reduces thrombus weight and improves patency in a rabbit venous thrombosis model

OBJECTIVE

To study whether locally administered recombinant inactivated human coagulation factor VIIa (FFR-rFVIIa) would reduce the thrombus formation and improve patency in an experimental venous thrombosis model without inducing systemic changes in the coagulation.

DESIGN

Experimental double-dummy randomised study.

MATERIALS

In 20 healthy New Zealand White rabbits both jugular veins were exposed under general anaesthesia.

METHODS

The thrombi were induced in a 10 mm long jugular vein segment with a combination of chemical destruction of the intima and a restriction of the bloodflow. Each segment was treated with either FFR-rFVIIa or placebo injected directly into the vein.

RESULTS

1.5 mg topically applied FFR-rFVIIa significantly reduced the thrombus weight (p < 0.001). The 30 and the 120 min patency tests were significantly improved (p < 0.05 and p < 0.001, respectively) Plasma analyses (APTT, dilute-TF time, FVII protein) were evaluated as baseline, 3 min after declamping and at sacrifice. No prolongation of the clotting times were seen. FFR-rFVIIa protein was detected in minute amounts (ng/ml); however, this was not enough to prolong the dilute-TF time.

CONCLUSIONS

Local application of recombinant active-site inhibited human FVIIa reduced both thrombus weight and improved patency significantly in an experimental venous thrombosis model without affecting the systemic clotting times.

General principles of small animal blood component administration

Administration of blood components instead of whole blood has become the most important means of transfusion support in dogs and in some settings in cats as well. Component administration entails the transfer of biological material and carries an inherent risk of disease transmission and adverse reactions. This article reviews the indications, pretransfusion considerations, and follow up in small animal patients receiving blood component therapy.

Modern veterinary blood banking practices and their applications in companion animal practice

There are two main reasons for blood component therapy: the need for an increase in oxygen-carrying capacity and improved hemostasis. Additionally, blood component therapy is used to increase plasma protein concentrations. Component therapy entails separating whole blood into its cellular and plasma components and administering the appropriate blood component based on the patient's needs. General considerations such as compatibility, defined expectations of benefits, and topics including specific disease screening, preparation of blood components, preparation of blood products for administration, and typing and crossmatching in relation to blood component therapy and its application in companion animal practice are discussed.

Canine transfusion reactions and their management

There is a wide range of mechanisms by which transfusion reactions may occur. These reactions typically are categorized as immune- or nonimmune-mediated and also as to whether they are acute or delayed in nature. The type and severity of clinical signs vary according to the specific reaction present. Many reactions can be prevented with the use of standard and appropriate transfusion medicine procedures. These methods include careful collection and storage of blood products, adequate screening and blood typing of donor dogs, crossmatching donor and recipient blood, use of component therapy, correct administration of blood products, and the use of pretransfusion prophylaxis when appropriate. Because many reactions are dose dependent, careful monitoring of transfusions cannot be overemphasized. Rapid recognition of a transfusion reaction and immediate discontinuation of the transfusion, along with appropriate supportive therapy, is essential for the successful treatment of transfusion reactions. A summary of transfusion reactions including clinical signs, diagnosis, and basic treatment protocols is given in Table 4. When used appropriately, transfusion of blood products can be a highly beneficial, low-risk form of therapy.

Platelet dysfunction associated with immune-mediated thrombocytopenia in dogs

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 (Ig)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.

Comparison of microscopic and flow cytometric detection of platelet antibody in dogs suspected of having immune-mediated thrombocytopenia

A flow cytometric platelet immunofluorescence assay (FC-PIFA) was compared with a previously developed microscopic platelet immunofluorescence assay (MI-PIFA) for detection of circulating platelet antibody. Both assays were performed on serum from 10 healthy dogs with normal platelet count, and on serum from 27 thrombocytopenic dogs--18 had primary immune-mediated thrombocytopenia (IMT), and 9 had IMT in addition to other immune-mediated disease (secondary IMT). Both assays yielded negative results for all control dogs. The MI-PIFA and FC-PIFA results were in agreement in 23 dogs with IMT (14 positive and 9 negative). There was linear correlation between MI-PIFA scores and FC-PIFA results (r = 0.873). Positive results were obtained for 55.5% of the dogs with suspected IMT, using the MI-PIFA, compared with 67%, using the FC-PIFA; however, the difference was not statistically significant. Use of fresh or frozen fixed donor platelets as the antigen source yielded similar results in the FC-PIFA.

Detection of antiplatelet antibody with a platelet immunofluorescence assay

An indirect platelet immunofluorescence assay (PIFA) was developed for detection of circulating antiplatelet antibody in dogs with suspected immune-mediated thrombocytopenia (ITP). The PIFA was performed on 10 healthy dogs with normal platelet counts; 76 thrombocytopenic dogs, 20 of which were suspected of having ITP; and 18 dogs with other diseases and normal platelet counts. All normal dogs and negative test results. Fourteen (70%) of 20 dogs suspected of having ITP had positive test results. Fifteen of the remaining 56 thrombocytopenic dogs had positive test results, 9 had cancer and 6 had other immune-mediated diseases including systemic lupus erythematosus (SLE). In this study, the PIFA assay seemed to be more sensitive (70%) than the megakaryocyte immunofluorescence assay (41%) in the diagnosis of ITP. Of the 9 PIFA-positive dogs with neoplasia, 6 had lymphoproliferative disorders. The PIFA was positive in 5 of 18 diseased dogs with normal platelet counts. There was an inverse relationship between the platelet count and the intensity of fluorescence in the PIFA-positive dogs. We conclude that the PIFA is a sensitive screening method for detecting circulating antiplatelet antibody.