Page 37 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

4 SECTION | I General

VetBooks.ir maximize its potential impact. Next, there is a section on chemical and indistinguishable from those occurring natu-
rally or from a variety of other causes.
the sources of information that may be obtained either
Toxicology, in a sense, dates back to the earliest activ-
through observation or experimentation. These sources
may include studies on the species of interest, i.e., people ities of humans. By observation, people came to learn that
or some other specific animal species, controlled exposure which could be ingested without harm and, by contrast,
studies in the species of interest, studies in other species, the foodstuffs to be avoided because of their harmful
investigations using tissues and cells and structure- properties. They also came to know which animal
activity analyses. This is followed by a section discussing venoms, plant extracts, and other materials could be used
the design of experimental studies to optimize the inter- for hunting, warfare, and assassination. No doubt as ani-
pretation and use of the results. The chapter concludes mals were domesticated, it became apparent that the
with a discussion of key toxicologic descriptors and human observations and practices could be extended
a brief conclusions section. to domestic animals. Unfortunately, domestic animals are
not always as astute as people in learning to avoid poison-
ous plants and other harmful situations. Thus, veterinary
practitioners still encounter toxicoses involving animals
HISTORICAL PERSPECTIVE ingesting poisonous plants.
The history of toxicology has been well documented by
Historical Events
several contemporary authors (Milles, 1999; Gallo, 2013;
The father of modern toxicology is generally acknowl- Lane, 2014). The history of veterinary toxicology has not
edged to be Aureolus Philippus Theophrastus Bombastus been as well documented, although it is apparent that
von Hohenheim (1493 1541), who referred to himself veterinary toxicology has been an integral part of veterinary
as Paracelsus, from his belief that his work was beyond medicine since the earliest time of the profession.
the work of Celsus, a first century Roman physician Veterinary medicine is a specialized branch of medical
(Pagel, 1958). Paracelsus is credited with the well-known science with formal programs of study leading to a profes-
statement, “All substances are poisons; there is none sional degree. The history of veterinary medicine has been
which is not a poison. The right dose differentiates reviewed by several authors (Smithcors, 1957; Stahlheim,
a poison from a remedy.” Paracelsus advanced many 1994; Swabe, 1999; Wilkinson, 2005). Theroleof
views that were revolutionary for his time that are now veterinary toxicology in the veterinary curriculum is well
accepted as fundamental concepts for the field of toxicol- documented for one of the earliest veterinary medical
ogy. In contrast to earlier emphasis on mixtures, he colleges, that at the Free University of Berlin. Wilsdorf and
focused on the toxicon as a specific primary chemical Graf (1998) provide an account of the development of
entity that was toxic. Paracelsus advanced four fundamen- veterinary toxicology at that university from 1790 to 1945.
tal concepts. Oehme (1970) has briefly reviewed the development of
veterinary toxicology as a discipline in the United States.
1. Experimentation is required for examining responses
to chemicals.
2. A distinction should be made between the therapeutic Textbooks
and toxic properties of chemicals.
In the English language, the earliest veterinary toxicology
3. The therapeutic and toxic properties are something
publication I am aware of is a Synopsis of Veterinary
closely related and distinguishable by dose.
Materia Medica, Therapeutics and Toxicology (Quitman,
4. It is possible to ascertain a degree of specificity for
1905) apparently used at my alma mater, Washington
chemicals and their therapeutic or toxic effects.
State University College of Veterinary Medicine, in the
It is obvious from the foregoing that toxicology and early part of the 20th century. I am uncertain of the extent
pharmacology are closely related fields of scientific to which this synopsis may be based on a French text by
endeavor. Pharmacology is focused on drugs, including Kaufmann (1901). The earliest English language veteri-
both their effectiveness and safety. Pharmaceutical agents nary toxicology textbook I was able to locate was that
are drugs used to diagnose, cure, treat, or prevent disease. authored by an Englishman, Lander (1912). This book
Toxicology is concerned with all kinds of chemicals, was also prepared in a second edition (1926) and a third
including pharmaceutical agents, and other agents that edition was prepared by an Irishman, Nicholson (1945).I
may, at some level of exposure, cause adverse health am uncertain as to how widely it was used in the United
effects. As will be noted at several places in this chapter, States. The text included four sections: a brief introduc-
toxicology is increasingly concerned with low-level expo- tion to toxicology followed by sections on classes of toxi-
sures for which the adverse effects, if any are observed or cants, mineral or inorganic poisons, organic poisons and
estimated to occur, may not be specific to a particular drugs, and poisonous plants. This last section represented