Veterinary Medicine - August 2007 - (Page 535)

TABLE 3 Laboratory Submission of Platelet-Surface-Associated Antibody Testing and Antimegakaryocyte Antibody Testing Diagnostic Laboratory Kansas State University Department of Diagnostic Medicine 1800 Denison Ave. Manhattan, KS 66506 (785) 532-4617 University of California-Davis Department of Pathology, Microbiology, & Immunology 33 VMTH, Room 1024 Davis, CA 95616 (530) 752-7373 University of Tennessee College of Veterinary Medicine Department of Comparative Medicine Clinical Immunology Service Room A-239 2407 River Drive Knoxville, TN 37996-4500 (865) 974-5643 Sample EDTA blood Assay Platelet-surface-associated antibody by flow cytometry (dogs and cats) Antibody test for precursor cells by immunofluorescence Antimegakaryocyte antibody test by immunofluorescence Bone marrow aspirate slides (two—unstained, nonfixed) Bone marrow aspirate slides (two—unstained, nonfixed) wrapped in foil; include the results of bone marrow cytology or a third bone marrow cytology slide EDTA blood (0.5 ml); ship on ice Platelet-surface-associated antibody by flow cytometry (dogs) initial platelet count to a degree that the patient can be discharged earlier from the hospital.14 In addition to stimulating increased platelet release from bone marrow, vincristine may also have mild immunosuppressive effects. Vincristine is given as a single dose of 0.02 mg/kg intravenously.8,14 Increases in platelet numbers often occur within two or three days.8 Administration of vincristine as a constant-rate infusion or incubated with a platelet transfusion has also been reported, but these routes have not been thoroughly evaluated. 2,8 Vincristine is a strong vesicant if extravasated and should be given through a well-placed catheter; few other side effects are generally seen with a single dose.8,14 In vitro vincristine decreases canine platelet function, but in vivo alterations in platelet function are not well-documented.8 Other immunosuppressants. For patients with primary immune-mediated thrombocytopenia that fail to re- spond to glucocorticoids, additional medications may be used concurrently. Dogs with intolerable side effects from glucocorticoids may be given additional immunosuppressive medications to allow tapering or discontinuation of the corticosteroids.6,8 Azathioprine is the most common option.19 Azathioprine is an immunosuppressive agent that reduces the production of antiplatelet antibodies.8 It is given at a dose of 2 mg/kg orally every 24 hours. After two to four weeks, if the platelet count is normal, taper the azathioprine in tandem with the prednisone to the lowest effective maintenance dose.2,8 Potential side effects of azathioprine include myelosuppression, pancreatitis, hepatopathy, and predisposition to infection.8 Dogs deficient in thiopurine methyltransferase may be more susceptible to side effects.22 Alternatively, cyclophosphamide (50 mg/m2 orally on the first four days of the week for a maximum of four to five months) may be used in conjunc- tion with prednisone for immunosuppression. Cyclophosphamide is usually less well-tolerated than azathioprine for long-term use. Potential side effects that limit its long-term use include myelosuppression, susceptibility to infection, and hemorrhagic cystitis. 8 Studies in dogs with immune-mediated hemolytic anemia suggest that cyclophosphamide may no longer have a role in treating this immune-mediated blood dyscrasia.23,24 Cyclosporine (5 mg/kg orally every 12 to 24 hours) may be used instead of, or in addition to, azathioprine. The use of cyclosporine in treating immunemediated thrombocytopenia has been described in a small number of patients, and the drug’s potential side effects include vomiting, diarrhea, anorexia, and weight loss.2 Other therapeutic options In cases refractory to standard immunosuppressive medication, other therapeutic options include splenec- VETERINARY MEDICINE August 2007 535

Table of Contents Feed for the Digital Edition of Veterinary Medicine - August 2007

Contents A Veterinary Medicine Interview Veterinary Voices Idea Exchange Diagnosis and Treatment of Solar Dermatitis in Dogs Diagnostic Imaging for Linear Foreign Bodies in Cats Overcoming the Diagnostic and Therapeutic Challenges of Canine Immune-Mediated Thrombocytopenia Ophthalmic drugs: What’s new? CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - August 2007

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