Preface The Veterinary toxicology, in recent years, has acquired greater importance than ever before because of increasing and indiscriminate use of farm chemicals and drugs accompanied by rapid degrading impact of environmental pollution on health of animals. The indiscriminate feeding habits of domestic animals especially in developing countries make them more prone to the impact of natural toxicants especially Phytotoxins and Mycotoxins. Toxicology has been recognized as a separate discipline in veterinary sciences both at undergraduate and post graduate levels for the last four decades and a lot of  emphasis has been given on its teaching, research and practical utility from clinical point of view. This was written with two goals in mind i) to provide a textbook for veterinary students that would supplement their classroom instruction and ii) to supply a valuable aid to practicing Vet Clinicians. The book has been prepared in a most comprehensive manner with up to date reference which offers invaluable, clinically oriented guidance on numerous potentially toxic substances. In addition, to covering traditional and non-traditional areas of toxicology it provides a wealth of quick reference charts and tables that put vital information at your finger tips in seconds. It is needless to say that the intent of the author is to primarily provide a comprehensive information on the basic and applied principles of toxicology including clinical toxicology.

Toxicology is defined as the study of chemical or physical agents which interact with biologic systems to produce a response in the organisms. Toxicity is the relative ability of a substance to cause injury to biologic tissue. Given the broad range of toxicities any substance might eventually invoke in an organism, it is easy to understand the wisdom of Paracelsus (1493-1541) when he said, “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy”. Toxicology is the study of the harmful effects of chemical compounds on biologic systems, including their properties, actions, and effects. The toxic agent is referred to as a toxicant or poison. The term toxin refers to poisons produced by a biologic source (eg, venoms, plant toxins); the redundant term biotoxin is occasionally used. Toxicosis, poisoning, and intoxication are synonymous terms for the disease produced by a toxicant. Toxicity (sometimes incorrectly used instead of poisoning) refers to the amount of a toxicant necessary to produce a detrimental effect. Hazard describes the likelihood of poisoning under conditions of use.

Definitions       •    Toxicology: Knowledge (or science) of poisons, including their chemical properties, identification, biological effects, and the treatment of conditions they cause.     •    Poison: Any solid, liquid, or gas that, when introduced into or applied to the body, can interfere with the life processes of cells of the organism - by its own inherent chemical properties - without acting mechanically and regardless of temperature.     •    Poison = Toxicant: The term poison is now used less often. Reason: Historical application of the term (malicious) vs. a compound used as a feed additive, agricultural, or other chemical - manufactured to fulfill a perceived human need.

Arsenic General Information     1.    Exists in elemental form (-3), trivalent As+3 and pentavalent As+5 oxidation states     2.    Arsenic is an essential element for rats, chicks, mini-pigs and goats     3.    The second most important pollutant for livestock.  Source Inorganic form is used in paints. Pasture near smelters may be contaminated.  Industrial effluents released into nearby water body. Insecticides (arsenic trioxide, lead arsenate).  

Nitrate – Nitrite Poisoning Sources Accidental ingestion/grazing of Plants which are Nitrate accumulators

Introduction Plants are the main source of nutrition to farm animals for their maintenance and production.  But, under certain conditions, plants intoxicate farm animal life due to the presence of some deleterious substances called phytotoxins. Such plants include a variety of fodder plants (Jowar, wheat straw, Lucerne), grasses (Millet grass), ornamental or fencing plants (Crotons, Nerium sps) and weeds. (Tribulis) in the farm premises. Generally, farm animals avoid such plants and weeds due to their unpleasant taste and offensive odor but during fodder scarcity caused by drought, floods or overgrazing, animals consume these plants. In addition, animals introduced into new areas, stall fed animals also sometimes lose their sense of discrimination and ingest such plants containing phytotoxins.

Introduction  In the thirst of modernization and industrialization man has contributed pollution to the life and ecology of plants, animals and microbes. Increased demand for food and fiber has lead to the chemicalization of agriculture we have reached to such a stage that modern agriculture is dependent on high yielding varieties, which can only be grown under the influence of fertilizers and pesticides. Pesticides are the man made chemicals which are being used to produce enough cheap food. In India, 90,000 MT of technical grade pesticides are used annually to control pests and plant diseases. The pesticides are classified as insecticides, fungicides, weedicides, herbicides, nematodicides and rodenticides; of which insecticides constitutes 77% of the total pesticides used in different agricultural and animal husbandry practices and in public health operations.

Introduction The word mycotoxin is derived from myco, meaning mold and toxin, a poison. A great number of mold metabolites have been identified as mycotoxins. Thus mycotoxins are secondary fungal metabolites (i.e., metabolites not essential to the normal growth and reproduction of the fungus) which cause pathologic, physiologic, and/or biochemical lesions in other species (may include animals, plants, other microbes, etc.). Mycotoxicosis - Poisoning of a biological system by a mycotoxin. Mycotoxins  are  defined as toxic metabolites released by moulds under certain conditions conducive for their growth. Acute or chronic toxicoses can result from exposure to feed or bedding contaminated with toxins that may be produced during growth of various saprophytic or phytopathogenic fungi or molds on cereals, hay, straw, pastures, or any other fodder. A few principles characterize mycotoxic diseases:

Introduction  A toxin (Greek: ôïîéêüí, toxikon, lit. (poison) for use on arrows) is a poisonous substance produced by living cells or organisms that is active at very low concentrations. Toxins can be small molecules, peptides, or proteins and are capable of causing disease on contact or absorption with body tissues by interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin) A toxin is simply a poison that can affect the body by internal or external means. A toxin can be a chemical which occurs naturally or in synthetic form. More than 120,000 human-made chemicals have been introduced into the environment, in one form or another, and this number continues to grow each year at a phenomenal rate. At the same time, microbial toxins, being influenced by the vast numbers of chemicals, are mutating beyond belief.

Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the physical systems or living organisms they are in.   Pollution can take the form of chemical substances, or energy, such as noise, heat, or light energy. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Sometimes the term pollution is extended to include any substance when it occurs at such unnaturally high concentration within a system that it endangers the stability of that system. For example, water is innocuous and essential for life, and yet at very high concentration, it could be considered a pollutant.

Definition  Radiation poisoning, also called “radiation sickness” or a “creeping dose” is a form of damage to organ tissue due to excessive exposure to  radiation. The term is generally used to refer to acute problems caused by a large dosage of radiation in a short period, though this also has occurred with long term exposure to low level radiation. Many of the symptoms of radiation poisoning occur as ionizing radiation interferes with cell division. The clinical name for “radiation sickness” is acute radiation syndrome . A short exposure can result in acute radiation syndrome; chronic radiation syndrome requires a prolonged high level of exposure. A chronic radiation syndrome does exist but is very uncommon; 

Chemical warfare involves using the toxic properties of chemical substances to kill, injure or incapacitate an enemy. Chemical warfare is different from the use of conventional weapons or nuclear weapons because the destructive effects of chemical weapons are not primarily due to any explosive force. The offensive use of living organisms (such as anthrax) is considered to be biological warfare rather than chemical warfare; the use of nonliving toxic products produced by living organisms (e.g., toxins such as botulinum toxin, ricin, or saxitoxin) is considered chemical warfare under the provisions of the Chemical Weapons Convention. Under this Convention, any toxic chemical, regardless of its origin, is considered as a chemical weapon unless it is used for purposes that are not prohibited (an important legal definition, known as the General Purpose Criterion)

Appendix - 1 Differential Diagnosis of Poisons based on Clinical Signs

Index 5-hydroxytryptamine 346 A Abrin 23, 196 Abrus 195, 197 Acacia 269 Acepromazine 349 Acetate 53, 54, 103, 104, 292 Acetic acid 47, 170, 181, 186, 352 Acetone 23 Acetylcholine 47, 107, 231, 292, 401, 406, 411 Acetylcholinesterase 80, 231, 290, 291, 292, 297, 299 Acetylcysteine 138 Acids 21, 23, 33, 36, 39, 57, 58, 62, 68, 71, 72, 81, 84, 85, 115, 178, 181, 182, 183, 185, 186, 187, 201, 213, 220, 263, 271, 281, 289, 307, 309, 315, 329, 330, 358, 376, 395, 418, 420, 422, 426, 432, 433, 434 Adrenaline 23 Affinity 36, 37, 148, 267, 292, 314, 424 Aflatoxins 22, 26, 69, 70, 258, 354, 359, 361, 364, 368 Agonist 383 Air pollutants 415, 416, 417, 418 Alcohols 289, 290 Aldehydes 23, 44, 45, 68, 419 Aldicarb 16, 280, 291 Aldrin 280, 286, 287 Alkalies 21, 23, 68 Allethrin 300 Aluminium phosphide 282 Amaranth 21, 233 Amitraz 280, 304, 305, 306 Ammonia 25, 73, 153, 176, 177, 178, 179, 180, 181, 194, 364, 419, 460 Ammonium chloride 33, 84, 201 Ammonium fluoride 167 Ammonium nitrate 152