Jennifer S. Thomas

Nephrotic Syndrome Resulting in Thromboembolic Disease and Disseminated Intravascular Coagulation in a Dog

Thromboembolic disease and progression to disseminated intravascular coagulation (DIC) are potential life-threatening complications for dogs with nephrotic syndrome. Platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), plasma concentration of fibrinogen degradation products (FDPs), antithrombin III (ATIII), protein C, and plasminogen were used to identify hemostatic abnormalities in a dog with nephrotic syndrome. Pulmonary thromboembolic disease was diagnosed by thoracic radiography, arterial blood gas analysis, and pulmonary scintigraphy. Prompt recognition and treatment of hemostatic complications is necessary in dogs with nephrotic syndrome.

VON WILLEBRAND'S disease in the dog and cat

Von Willebrands disease (vWD) is a bleeding disorder that is recognized commonly in dogs but rarely in cats. This article presents the pathophysiology and clinical features of vWD, including a discussion of inherited and acquired types of vWD. Laboratory evaluation and treatment of vWD are reviewed.

Platelet Aggregation and Adenosine Triphosphate Secretion in Dogs with Untreated Multicentric Lymphoma

Whole-blood platelet aggregation and adenosine triphosphate secretion were measured in 15 dogs with untreated multicentric lymphoma and 10 normal control dogs to determine if dogs with lymphoma have altered platelet function. Dogs with quantitative platelet disorders (ie, thrombocytopenia or thrombocytosis) or with clinical evidence of a bleeding disorder were excluded from the study. Platelets from affected dogs had significantly greater maximum aggregation than those from control dogs, suggesting that platelets from dogs with lymphoma are hyperactive. Platelet hyperactivity may play a role in the development of hemostatic disorders (eg, disseminated intravascular coagulation) or in tumor metastasis. Further investigation is needed to determine if modification of platelet function in patients with lymphoma affects disease progression or outcome.

Hemorrhagic Diathesis Associated with a Hereditary Platelet Disorder in Simmental Cattle

A severe bleeding disorder in Simmental cattle has been described in widespread locations in the USA and Canada. The clinical findings are consistent with a hemophilia-like disease or, more precisely, a hereditary hemorrhagic diathesis and include spontaneous epistaxis, hematuria, and excessive bleeding associated with trauma or standard management procedures such as tattooing, ear tagging, and castration. A preliminary investigation of this defect showed that blood-platelet numbers and coagulation profiles of affected cattle were normal. Affected animals have a marked dysfunction of platelets (thrombopathy), termed Simmental hereditary thrombopathy. The defect is very similar or identical to that described in the same breed by 2 other laboratories.

Complications common to ventricular assist device support are rare with 90 days of DeBakey VAD® support in calves

The DeBakey VAD® is a miniaturized, electromagnetically driven axial flow pump intended for long-term ventricular assist. Safety and performance data from six calves implanted with the complete DeBakey VAD® system are reported elsewhere; here we describe complications and necropsy findings for these same six animals, all of which survived 90 days. The study was conducted according to a uniform protocol, which included anticoagulation and antibiotic prophylaxis. Clinical complications tracked included bleeding, cardiovascular abnormalities (e.g., arrhythmias, tachycardia unrelated to pain, bradycardia), hemolysis, hepatic dysfunction, renal dysfunction, thromboembolism (neurologic or peripheral), or infection. Each adverse event was retrospectively categorized with regard to severity (mild, moderate, severe) and relationship to device. Clinical findings were confirmed by necropsy. There was no evidence of systemic infection, thromboembolism, hemolysis, or renal or hepatic dysfunction in these six animals during the study period. A single adverse event was noted in each of two of the calves. Both events were considered mild according to the predefined criteria. Bleeding related to the surgical implantation procedure and requiring reoperation occurred in one animal. The other animal had evidence of a superficial infection at the exit site of the cables on the left lateral thoracic wall; the infection did not extend into the thoracic cavity. Chronic, healed small renal infarct scars were present in several animals. Mild valvular endocardiosis was observed in two calves and mild fibroelastosis was present in the endocardium at the site of the inflow cannula in three calves; however, these lesions were not considered clinically significant. No other gross or histologic abnormalities were noted at necropsy. In conclusion, calves implanted with the complete DeBakey VAD® for 90 days demonstrated few complications and had no significant necropsy findings. Complications common to ventricular assist device (VAD) support (i.e., hemolysis, infection, bleeding, thromboembolism) were rare during long-term support (90 days) with the DeBakey VAD.

Telomerase Enzyme Activity as a Diagnostic Tool to Distinguish Effusions of Malignant and Benign Origin

Telomerase enzyme activity is high in populations of cells that are dividing, and is low or undetectable in quiescent cell populations. Activation of telomerase in tissues that normally lack the capacity for self-renewal is strongly correlated with neoplasia. Telomerase activity can be detected in samples containing very small numbers of cells and studies of human patients suggest that measurement of telomerase activity may be useful for the evaluation of samples that can be obtained in a minimally invasive manner. This study compares the presence or absence of telomerase activity with cytologic evaluation of body cavity effusions, to determine if neoplasia is the underlying cause for the effusion in dogs and cats. Detection of telomerase in effusions was no more sensitive than cytologic evaluation for the identification of underlying neoplasia, and was less specific (telomerase assay: sensitivity = 50%, specificity = 83%; cytology: sensitivity = 50%, specificity = 100%). We conclude that although the telomerase assay may constitute a useful adjunctive test for the diagnosis of neoplasia in some dogs and cats with body cavity effusions, the results of this assay are not sufficiently reliable to be used as a sole diagnostic test.

Presumed Immune-Mediated Hemolytic Anemia in a Blue-Crowned Conure (Aratinga acuticaudata)

Abstract Immune-mediated hemolytic anemia occurs infrequently in poultry and is undocumented in parrots. In this study, we describe a blue-crowned conure (Aratinga acuticaudata) with a strongly regenerative anemia, a predominance of round, small erythrocytes (presumed spherocytes), leukopenia followed by leukocytosis, elevated plasma protein, biliverdinuria, and polyuria. Radiography and ultrasonography demonstrated a markedly enlarged spleen. After immunosuppressive treatment with prednisolone, the anemia, abnormal erythrocyte morphology, and biliverdinuria resolved but returned promptly after discontinuation of the therapy. We propose that this conure suffered from an immune-mediated hemolytic anemia.

A primary platelet disorder of consanguineous simmental cattle

A severe hereditary hemorrhagic diathesis in Simmental cattle has been identified in North America. Platelet numbers and coagulation profiles of affected cattle are normal. We have further characterized the severe dysfunction of platelet aggregation. All agonists tested elicited normal shape change. Aggregations in response to ADP, A23187, and collagen were absent. Aggregations were decreased or required more time for completion in response to PAF and thrombin. No ultrastructural abnormalities were observed in transmission electron micrographs. Dense granule release of ATP in response to PAF was normal. Thrombin-induced aggregation was dependent upon external calcium concentration in normal but not affected animals. Clot retraction in the blood from affected animals was abnormal. The data implicate a defect of Ca++ mobilization or utilization.

Thrombosis of the caudal vena cava presenting as an unusual cause of an abdominal mass and thrombocytopenia in a dog.

Thrombosis of the caudal vena cava in a dog secondary to metastatic neoplasia is described. The dog had a palpable abdominal mass and persistent thrombocytopenia due to a thrombosed caudal vena cava that was surgically removed. A few days after its removal, the dog died and neoplastic cells of neural crest origin were identified at the edge of the thrombus. Massive thrombosis can be an unusual cause of platelet consumption, leading to thrombocytopenia and disseminated intravascular coagulation. Deep vein thrombosis of the vena cava can occur in dogs and may mimic an abdominal mass. Multiple mechanisms may be involved in the development of venous thrombosis, including endothelial damage by neoplastic cells and the presence of a hypercoagulable state secondary to neoplasia. Extensive collateral circulation may allow removal of diseased vena cava.

Comparison of platelet aggregation and adenosine triphosphate secretion in whole blood and platelet-rich plasma from normal dogs

Platelet aggregation and adenosine triphosphate (ATP) secretion were measured in whole blood and platelet-rich plasma (PRP) from normal dogs using electrical impedance and turbidimetric techniques. General appearance of the aggregation curves, ATP secretion, and aggregation rate were similar in PRP in response to adenosine diphosphate (ADP) or collagen using both techniques. In response to ADP, aggregation was detected sooner while the maximum aggregation response decreased at a relatively greater rate with decreasing agonist concentrations using the turbidimetric technique. Shape change was consistently detected using the turbidimetric, but not the impedance, technique. Using electrical impedance, there were differences between whole blood and PRP in aggregation and ATP secretion responses which depended on the agonise used to activate the platelets. In response to ADP, aggregation responses were lower in whole blood relative to PRP. In response to platelet-activating factor (PAF), maximum aggregation was greater in whole blood while aggregation rate and ATP secretion were greater in PRP. In response to collagen, aggregation response and ATP secretion were lower in PRP. Dilution of PRP with buffer instead of platelet-poor plasma (PPP) lessened many of the differences between whole blood and PRP samples. These findings suggest that plasma constituents and blood cells other than platelets affect aggregation and secretion in an agonist-dependent manner.