Thrombocytopenia and drugs

Retrospective evaluation of the short-term response of human intravenous immunoglobulin therapy in the management of canine immune-mediated thrombocytopenia (2010-2015): 27 cases

OBJECTIVE

To describe the short-term response, early prognostic markers, and survival after treatment of canine immune-mediated thrombocytopenia (ITP) with human intravenous immunoglobulin (hIVIG) and methylprednisolone.

DESIGN

Retrospective cohort study.

SETTINGS

Private referral veterinary medical center.

ANIMALS

Twenty-seven client-owned dogs with primary or secondary ITP.

INTERVENTIONS

All dogs received 2 mg/kg IV methylprednisolone once daily and a single infusion of 5% hIVIG administered over 6-12 hours.

MEASUREMENTS AND MAIN RESULTS

A substantial increase in platelet count within 60 ± 12 hours post-hIVIG infusion (T60) was observed in 19 of the 27 (70%) dogs with ITP (responders). Thirty-four variables, including serum immunoglobulin (Ig) G concentration 24 ± 12 hours post-hIVIG infusion (T24IgG) and increase in serum IgG concentration 24 ± 12 hours post-hIVIG infusion (T24ΔIgG), were compared between responders and nonresponders at 5 different time points. Mortality rates of responders and nonresponders were evaluated 14 days post-hIVIG infusion. Serum T24IgG and serum T24ΔIgG were both significantly higher at T60 in responders. All responders were alive 14 days post-hIVIG infusion, and their mortality rate was significantly lower compared with nonresponders.

CONCLUSIONS

Responder dogs had an excellent 14-day survival rate. Serum T24IgG and serum T24ΔIgG concentrations accurately predicted response status at 60 hours post-hIVIG infusion.

Histopathology of Bone Marrow

As a major hematopoietic and lymphoid organ, morphological evaluation of the bone marrow is an important component of toxicity or safety assessment studies. While definitive characterization of bone marrow lesions often requires cytological aspirates or smears, assessment of histological bone marrow sections provides information regarding tissue architecture and hematopoietic status that is relevant for the detection of direct or indirect responses to chemical exposure. A variety of lesions have been observed in bone marrow. For example, lesions involving disturbances in growth, degenerative changes, inflammatory changes and neoplasia have been described. Lesions identified in hematoxylin and eosin-stained sections typically represent changes in the hematopoietic cell lineage and/or stromal cells since definitive identification of lymphoid cells is difficult except in cases of lymphoma. This review provides a descriptive and pictorial representation of a wide range of bone marrow lesions. Since large animal-to-animal variation may exist and there can be collection site- and age-related differences, it is imperative that the pathologist reviews all potential treatment-related findings against appropriate concurrent controls.

A review of immunologic diseases of the dog

The following review is based on notes used in the teaching of clinical immunology to veterinary students. Immune diseases of the dog are placed into six different categories: (1) type I or allergic conditions; (2) type II or auto- and allo-antibody diseases; (3) type III or immune complex disorders; (4) type IV or cell-mediated immune diseases; (5) type V conditions or gammopathies; and (6) type VI or immunodeficiency disorders. Separate discussions of transplantation immunology and the use of drugs to regulate unwanted immune responses are also included.

Canine idiopathic thrombocytopenic purpura

Canine idiopathic thrombocytopenic purpura (ITP) is a disease in which antibodies bound to the surface of platelets mediate premature platelet destruction by macrophages. ITP in dogs and chronic ITP in humans are analogous diseases. This article draws on information from the literature on ITP in dogs and in humans, and reviews the pathogenesis, diagnosis, and treatment of ITP in dogs.

Use of blood and blood components in canine and feline patients with hemostatic disorders

Therapy with blood and blood products related to hemostatic disorders in small animal practice is reviewed. Administration of platelet rich plasma and platelet concentrates in thrombocytopenia or thrombopathia is discussed. Vascular purpuras, vasculitis, and vascular inherited defects are also considered. Inherited coagulation disorders are summarized and the therapeutic choices in treating these disorders are also proposed. In addition, acquired coagulation disorders are briefly reviewed.

Hematologic emergencies

The most common life-threatening hematologic emergencies include hemorrhage and severe anemia. Successful treatment of these conditions depends on the emergency veterinarian having a thorough understanding of the possible etiologies of these conditions, and a systematic approach to diagnosis and therapy. Use of blood component therapy can be a life-saving technique in these patients. The goal of this article is to familiarize the emergency veterinarian with a systematic approach to the diagnosis and treatment of hematologic emergencies.

Platelets and coagulation

Hemostasis is a multiple-component system. In order to function properly it has become highly integrated with several strategies of control. Failure of the system or its control can result in life-threatening hemorrhage requiring transfusion. It is hoped that the information provided in this article has enhanced the reader's understanding of hemostasis in animals, and will enable the reader to make a more educated choice concerning transfusion therapy for the bleeding patient.

Laboratory abnormalities in patients with cancer

In this problem-oriented review of abnormalities associated with cancer, we have emphasized distinctive diagnostic points related to pathogenesis for each condition and outlined how the approach to management is determined by pathogenesis. For abnormalities of the complete blood count, it is important to distinguish between abnormalities directly related to marrow malignancy and abnormalities associated with extramarrow malignancy. Hemopoietic tumors consist of developmentally deficient blood cells produced by a clonal population of malignant stem cells. Tumors infiltrating marrow cause overcrowding in the limited marrow microenviroment. Extramarrow malignancies cause blood abnormalities, but the potential for normal marrow function is present. Abnormalities of blood cells secondary to therapy are usually clearly identified by consideration of clinical history. The initial differential diagnosis for hypercalcemia is malignancy. An aggressive diagnostic approach may be needed to identify the neoplasm, and therapy should incorporate measures to prevent renal failure. Hypoproteinemia and hyperproteinemia may be caused by neoplasia. Monoclonal gammopathies should be identified and may be associated with hyperviscosity syndrome. Hypoglycemia in the adult animal is most frequently caused by insulin-secreting tumors, but it has also been associated with hepatic and other tumors. Increased blood urea nitrogen, creatinine, lipase, amylase, and liver enzyme activities may also be caused by malignancy. Inadequate urine concentrating ability may be caused by hypercalcemia or malignancy-associated renal insufficiency. Hematuria in older animals is suggestive of urinary tract neoplasia. Exfoliated tumor cells may be identified in the urine sediment of these patients.

Abnormal bleeding

Animals with disorders of hemostasis are often presented as emergency patients and, as such, offer a challenge to the attending clinician. This article reviews the basic physiology of hemostasis and laboratory tests used for diagnosis. Guidelines for the evaluation and treatment of patients with bleeding disorders are provided.

Laboratory evaluation of hemorrhagic coagulopathies in small animal practice

Assessment of animals with a suspected hemorrhagic diathesis of unknown cause(s) should be methodical. Most acquired coagulopathies result from thrombocytopenia. A platelet estimate (from a blood smear) and/or a platelet count on a fresh blood sample therefore are useful first steps in case evaluation. If thrombocytopenia is present, the most likely causes are immune-mediated destruction of platelets, DIC, or megakaryocytic hypoplasia. These diagnoses can be pursued by further test, including antiplatelet antibody assays (for example, the platelet factor 3 tests or an ELISA test), measurement of FDP, and bone marrow biopsy, respectively. If the platelet count is normal, a buccal mucosa bleeding time test is a useful second step. If this is prolonged, most likely causes are vWD or a thrombocytopathy (functional platelet defect). von Willebrand's disease can be diagnosed by measurement of vWf concentration or activity. A normal bleeding time does not exclude a diagnosis of vWD, but suggests that the functional activity of vWf is not compromised markedly. If the bleeding time is normal, APTT and PT should be measured. A prolonged APTT with normal PT, in the clinical setting, implies a deficiency of factor XI, IX, or VIII. A prolonged PT with normal APTT indicates factor VII deficiency. Prolongation of both APTT and PT usually is caused by a deficiency of several factors and is seen most often in cases with vitamin K deficiency or antagonism. Obviously, if a particular cause is suspected from the case history or for other reasons, appropriate tests should be evaluated at the beginning. If these do not confirm the provisional diagnosis, the just-described protocol might be a useful one to follow.