Hematology Techniques And Concepts For Veterinary Technicians - 00 edition

Preface

As is stated in the title, this text is intended to introduce the field of hematology to the veterinary technology student and to assist in teaching the principles and procedures of collecting, handling, and preparing blood and other samples for a hematology laboratory. It will also be of benefit to the graduate technician who desires to refresh his or her memory on the basics of blood composition and how blood tests are performed, why they are run, and the calculations necessary to report results. And it will be informative for others with an interest in the technician's role in the clinical hematology laboratory.

It is not intended to be a comprehensive review of the literature or every possible technique, test, or type of equipment available. Numerous excellent books are available on specialized testing and diagnostic techniques for the veterinarian (see Recommended Reading). This book describes the normal appearance and function of the components of blood and discusses how changes from normal are measured. Basic information concerning the rationale for the laboratory tests and the importance of the obtained results is also included. Although interpretation and diagnosis are not the province of the technician, nor the intent of this text, recognition of the presence of some conditions is important, such as large numbers of circulating lymphoblasts with lymphosarcoma or the presence of identifiable blood parasites in an anemic animal. (As a clinical example, if a client brings in a rabid animal, it is important that the technician recognizes the condition, even though he or she should not make a diagnosis.) For this reason, a discussion of the significance of abnormal test results is also presented.

The content of this text is based on 16 years of instruction of veterinary technology students in hematology and other classes and several years of working with graduate technicians in private practice, at a veterinary teaching hospital, and in the military. Of equal importance to its preparation is the continual input received from veterinarians on what they desire and need from their graduate technicians.

For the most part, manual or semiautomated techniques are described in this text. Even though automated cell counters and chemical analyzers are becoming more available, accurate, and affordable, and local hospitals or commercial laboratories can provide numerical test results (often overnight, through courier services), the technician still must have a basic understanding of hematology concepts and techniques. Familiarity with the characteristics and variations of blood and blood cells is gained only by the processes of looking and doing. Once the technician is familiar with the rationale and mechanics of manual laboratory testing, results obtained from the various types of automated equipment are more readily understood and appreciated. Many screening tests, such as hematocrit, total protein, and bleeding time, are still completed more quickly, less expensively, and with more helpful results when performed by the technician. In addition, subjective evaluation of cellular morphology, such as toxic changes or cellular abnormalities, must still be accomplished by microscopic examination of a well-prepared blood smear by a trained and experienced observer.

In preparation of this book, I have assumed only a general knowledge of basic anatomy and medical terminology by the reader. Every attempt has been made to define, or present synonyms for, any newly introduced or potentially unrecognizable term. The text first describes the duties of the hematology laboratory technician. This is followed by brief descriptions of the fluid and cellular components of the blood (Chap. 2) to allow the student to begin identifying cells in the laboratory. Chapters 3?5 discuss blood collection and handling techniques. Routine laboratory test procedures are placed in a single chapter (Chap. 6) for ease of reference. The latter chapters present more detailed descriptions of red and white blood cell morphology, functions, and formation. A chapter introducing immunology is included to expand the student's awareness of the interrelationships of leukocyte function. Also presented are physiologic and pathologic cellular response mechanisms and specialized testing procedures, such as specimen collection, handling, and examination of bone marrow and cytology samples.

Tables of reference values presented throughout the text were prepared by the author but are based on data published by Dr. Maxine M. Benjamin in Outline of Veterinary Clinical Pathology, 3rd ed. (Ames: Iowa State University Press, 1989), with numerous additions and changes based on data from the literature or the author's experience. These tables are not intended for diagnostic purposes. They are meant to serve only as guides. As they learn testing procedures and calculations, students should produce results that approximate the reference values. The tables also demonstrate the variations that exist between species.

Eastern Wyoming College

Gregg L. Voigt, BS, DVM, MS, is an instructor in veterinary technology at Eastern Wyoming College, Torrington, WY. Prior to this Dr. Voigt had wide experience working with veterinary technicians for several years in private practice, as a military veterinarian at Fr. Bragg, NC, and while receiving his master's degree from the Pathology Department, Colorado State University.
Titles

''It's nice to finally have a hematology text written at the technician level that incorporates lab techniques as well as dynamics of blood cell formation and function. Testing is important, but understanding the relevance of test results (as well as normal vs. abnormal results) is also critical. This book appears to have done a thorough job of incorporating concepts of blood composition, formation, and funciton along with testing procedures.''

-- Barb Lewis, Morehead State University

Iowa State University Press Web Site, August, 2000

Preface


1 Introduction to the Hematology Laboratory
2 Blood Composition
3 Blood Volume and Effects of Blood Loss
4 Blood Collection and Handling
5 Blood Smears and Staining
6 Routine Hematology Laboratory Tests
7 Leukocyte Cell Types and Functions
8 Introduction to the Immune System
9 Erythrocyte Form, Function, and Indices
10 Erythrocyte Abnormalities
11 Anemias and Polycythemias
12 Hemostasis and Coagulation
13 Hematopoiesis and Bone Marrow Examination
14 Collection and Handling of Cytology Samples