Not Found
Locations

Brought to you by

Find information on animal health topics, written for the veterinary professional.

* This is the Veterinary Version. *

Factors Affecting the Activity of Poisons

By Barry R. Blakley, DVM, PhD, Professor, Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan ; Rob Bildfell, DVM, MSc, DACVP, Professor, Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University ; William D. Black, MSc, DVM, PhD, Professor, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph ; Herman J. Boermans, DVM, MSc, PhD, Professor of Toxicology, Director Toxicology Program, Ontario Veterinary College, University of Guelph ; Cecil F. Brownie, DVM, PhD, DABVT, DABFE, DABFM, FACFEI, Emeritus Professor, College of Veterinary Medicine, North Carolina State University ; Raymond Cahill-Morasco, MS, DVM, New, SeaPort Veterinary Hospital, Gloucester, MA ; Keith A. Clark, DVM, PhD, Retired Director, Zoonosis Control Division, Texas Department of Health ; Gregory F. Grauer, DVM, MS, DACVIM, Professor and Jarvis Chair of Small Animal Internal Medicine, Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University ; Sharon M. Gwaltney-Brant, DVM, PhD, DABVT, DABT, Toxicology Consultant, Veterinary Information Network (VIN) and Adjunct Faculty, College of Veterinary Medicine, University of Illinois ; Larry G. Hansen, PhD, Professor, Department of Veterinary Biosciences, University of Illinois ; Safdar A. Khan, DVM, MS, PhD, DABVT, Director of Toxicology Research, ASPCA Animal Poison Control Center, Urbana, Illinois ; Garrick C. M. Latch, MASc, PhD, Consultant ; Gavin L. Meerdink, DVM, DABVT, Clinical Professor, Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois ; Lisa A. Murphy, VMD, Veterinary Poison Information Specialist, ASPCA Animal Poison Control Center ; Frederick W. Oehme, DVM, PhD, Professor of Toxicology, Pathobiology, Medicine and Physiology, Comparative Toxicology Laboratories, Kansas State University ; Gary D. Osweiler, DVM, MS, PhD, Professor Emeritus, Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University ; Mary M. Schell, DVM, DABVT, DABT, Senior Toxicologist, ASPCA Animal Poison Control Center, Urbana, Illinois ; David G. Schmitz, DVM, MS, DACVIM (LA), Visiting Associate Professor, Department of Veterinary Large Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University ; Norman R. Schneider, DVM, MSc, DABVT, Veterinary Toxicologist, University of Nebraska ; Cheryl L. Waldner, DVM, PhD, Associate Professor, Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan

The consequences of poisoning depend on many factors in addition to the actual toxicity of the poison itself. The dose is a primary concern, but the exact amount of poison an animal has been exposed to is seldom known. The length of time and the number of times the animal is exposed are important. The way in which the animal is exposed affects how much of the poison is absorbed, how it spreads through the body, and perhaps how it is metabolized. The time of intake of the poison can also be a factor. For example, if the stomach is empty when an animal eats a poisonous substance, vomiting may occur. If the stomach is partly filled, the poison may be retained and lead to toxic effects. Environmental factors, such as temperature and humidity, affect rates of consumption and even whether or not some toxic agents are present. For example, many plant poisons are associated with seasonal or climatic changes, such as winter cold and rainfall.

Different species can react differently to a particular poison because of variations in absorption, metabolism, or elimination. For example, species unable to vomit, such as horses or rabbits, can be poisoned with a lower dose. The age, size, nutritional status, stress level, and overall health of an animal are important factors. In young animals, metabolism is compromised by underdeveloped systems.

The chemical nature of a poison determines its ability to dissolve. Poisons that dissolve in water spread more easily than those that do not. Substances added to the active ingredient, such as binding agents, outer coatings, and sustained-release preparations, also influence absorption. Generally, as absorption is delayed, toxicity decreases.

Droplet size is an important consideration in sprays and dips, because the dose increases when the droplets are larger. This is one of many reasons to closely follow label instructions and recommended applications. Only formulations intended for animals should be used.

* This is the Veterinary Version. *