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VetBooks.ir Chapter 4

Epidemiology of Animal Poisonings in Asia

Pawan K. Gupta

INTRODUCTION animals. In developing countries where there is hard evi-
dence of poisoning including sporadic incidents involving
It is well known that human, animal, and wildlife popula-
livestock and pets, surveillance is conducted by the veteri-
tions are continuously exposed to environmental polluting
nary institutions/departments or by the wildlife depart-
agents that are harmful to health (Gupta, 1986). Among
ments of each country. However, a centralized veterinary
them are natural and manmade chemicals such as metals,
poison control/information center does not exist in most
pesticides, organic and inorganic substances, and animal
countries in Asia. Therefore, in many Asian countries
venoms and toxins, including algal growth and industrial
information related to animal poisoning is either unavail-
wastes to which domestic animals and wildlife are fre-
able or inadequate and refers only to isolated case reports
quently exposed (Gupta, 2010a,b). In recent years, despite
when it does exist. Occasionally, epidemiological data on
the increasing level of regulation in the use and sale of
animal poisoning gathered by universities, research insti-
such products in Asia, their commercialization has inten-
tutes, government institutions, or independent laboratories
sified. Consequently, many cases of accidental poisoning
has been published in some local journals, which at times
have occurred. In addition, due to the continuous use of
becomes difficult to trace. It is therefore easy to conclude
these poisons, accidental or otherwise, these cases have
that available data are inadequate to provide sound
drastically increased all over the world, particularly in
estimates of the real incidence of poisonings in animal
developing countries. There is an ongoing need for care-
populations and are very likely to be subjected to signifi-
ful assessment of the risks caused by exposure to these
cant under-reporting (Litchfield, 2005; Gupta, 2016). This
chemicals. Information on the assessment of toxicity
chapter focuses on some of the most important poisonous
caused by these chemicals mainly comes from human and
chemicals and plants in Asia and provides an overview
animal studies (Smith, 2001). However, some supporting
of the poisoning episodes that have occurred in Asian
information may also be obtained from clinical and
countries.
in vitro studies. There are no reliable estimates of how
many animals suffer from acute poisonings or due to
long-term exposure. In general, epidemiology has been PESTICIDES (AGROCHEMICALS
particularly helpful in the evaluation of working environ- AND FERTILIZERS)
ments or other environments where exposure concentra-
tions are relatively high. However, several factors limit Evidence is accumulating that malicious poisoning by
the use of epidemiological studies by regulatory agencies pesticides is one of the most commonly used methods of
(Gupta, 2010a). For example, it is difficult to define the killing animals in Asia, but the magnitude of the problem
causal elements in epidemiological investigations, particu- and percentage of deaths in each country is unknown.
larly when complex exposures are involved. Another limi- Among all pesticides, organophosphate (OP) insecticides
tation is the frequent movement of animal populations poisons the insects and other animals, including birds,
and a large number of animal species available. As such, amphibians, and mammals (Gupta, 1986). This is fol-
studies on one population under controlled conditions lowed by other pesticides, such as carbamate insecticides,
may be difficult to apply to predict health effects on zinc phosphide, or aluminum phosphide (fumigants) and
another animal population. rodenticides. Dogs were involved in cases of anticoagu-
In some developed countries such as the United lant poisoning (over 60%) more than other domestic spe-
States, human poison control centers also collect data on cies. Occasionally, other pesticides such as the herbicide

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