61
also eat eggs, baby chickens, pigs and even lambs.9 Fortunately, it is possible to kill rats by
poisoning them because they do not have the ability to vomit or burp. Rats, however, do
have other strategies to defend themselves against toxins. One strategy is quickly learning
to avoid foods that offend their super-sensitive senses of taste and smell.10
Diseases
Rats are vectors and carry at least 18 diseases that affect people.11 The most serious are rat
bite fever (streptobacillary and spirillary), Lassa fever, typhus, poliomyelitis, meningitis,
trichinosis, Salmonella poisoning, hanta virus, leptospirosis (infectious jaundice) and,
of course, plague. It is for the latter that rats continue to carry their heinous reputation,
having been at the scene of a number of humanity’s greatest calamities. Rats and other
rodents are natural reservoirs of plague. Rats get plague from fleas. A flea injects its trunk-
like proboscis into the rat to withdraw blood. When a rat flea sucks in blood infected with
plague bacteria (Yersinia pestis), the plague bacteria multiplies and eventually kills the
flea. (Y. pestis derives its lethality from an endotoxin produced by the disintegration of the
lipopolysaccharide in the cell wall.12) Before the flea dies, it feeds again and regurgitates
the bacilli into the next rat as it feeds on that rat’s blood. When the rat dies, the flea senses
the temperature change of its host and leaves to find a warm, live rat. Because rats live
so close to man, rat fleas will feed on humans as second choice.13 The plague during the
Middle Ages killed up to one third of the population of most towns and villages.
Rats also carry up microbes from underground streams of sewage.14 Because rats live
in sewers and back alleys, search for food in gutters and contaminate our food and water
supply, they appear to be designed to desecrate the environment.
Animal Research
Historically, the rat has been an important model animal for physiological and biochemi-
cal studies. In 1909, Henry Donaldson, the Director of the Wistar Institute in Philadelphia,
wrote that it would be hard to find another animal that combined so many “virtues in so
compact and pleasing a form.”15 The rats described by Dr. Donaldson were domesticated
and generations removed from their wild progenitors. The metamorphosis of the rat from
an evil carrier of pestilence to a hero of modern medicine resulted from the work of many
researchers in various locales in the early 1900s. Rat breeding programs were carried out
at a number of institutions and resulted in brand-name rats such as Osborne-Mendel,
Long-Evans, Sprague-Dawley and Wistar. The latter were bred and distributed by the
Institute from 1906 through the 1940s and used in laboratories throughout the world.
Wistar rats comprised a number of strains of Rattus norvegicus, including several inbred
and numerous outbred, or random, strains.16 The Sprague-Dawley strain was started by
Bob Dawley in 1923 from wild rats found in a dump near a meat packing plant.17 Rats
were the first standardized laboratory animals.18
Rats can learn to crave the same drugs as humans, including alcohol, cocaine, nico-
tine and amphetamine, and have been known to overindulge.19 Rats are the preferred
model for the study of genetics of many complex diseases including hypertension, non-
insulin-dependent diabetes, renal disease and autoimmune and behavioral disorders.20
Pharmacokinetic studies at the University of Illinois indicate that rat and human systems
absorb and eliminate a number of drugs at similar rates. Their findings suggest that
testing new drugs on rats and perhaps one other species of animal may satisfy US Food
and Drug Administration (FDA) requirements for preclinical studies.21 The basic internal
structures of rats and humans are similar despite the disparities in length and diameter.
Similarities extend far beyond gross anatomy. Rats even have personalities they can be
sullen or cheerful depending upon their upbringing and circumstances. Surprisingly, rats
are generally sociable, curious and love to be touched.22
Rats!
also eat eggs, baby chickens, pigs and even lambs.9 Fortunately, it is possible to kill rats by
poisoning them because they do not have the ability to vomit or burp. Rats, however, do
have other strategies to defend themselves against toxins. One strategy is quickly learning
to avoid foods that offend their super-sensitive senses of taste and smell.10
Diseases
Rats are vectors and carry at least 18 diseases that affect people.11 The most serious are rat
bite fever (streptobacillary and spirillary), Lassa fever, typhus, poliomyelitis, meningitis,
trichinosis, Salmonella poisoning, hanta virus, leptospirosis (infectious jaundice) and,
of course, plague. It is for the latter that rats continue to carry their heinous reputation,
having been at the scene of a number of humanity’s greatest calamities. Rats and other
rodents are natural reservoirs of plague. Rats get plague from fleas. A flea injects its trunk-
like proboscis into the rat to withdraw blood. When a rat flea sucks in blood infected with
plague bacteria (Yersinia pestis), the plague bacteria multiplies and eventually kills the
flea. (Y. pestis derives its lethality from an endotoxin produced by the disintegration of the
lipopolysaccharide in the cell wall.12) Before the flea dies, it feeds again and regurgitates
the bacilli into the next rat as it feeds on that rat’s blood. When the rat dies, the flea senses
the temperature change of its host and leaves to find a warm, live rat. Because rats live
so close to man, rat fleas will feed on humans as second choice.13 The plague during the
Middle Ages killed up to one third of the population of most towns and villages.
Rats also carry up microbes from underground streams of sewage.14 Because rats live
in sewers and back alleys, search for food in gutters and contaminate our food and water
supply, they appear to be designed to desecrate the environment.
Animal Research
Historically, the rat has been an important model animal for physiological and biochemi-
cal studies. In 1909, Henry Donaldson, the Director of the Wistar Institute in Philadelphia,
wrote that it would be hard to find another animal that combined so many “virtues in so
compact and pleasing a form.”15 The rats described by Dr. Donaldson were domesticated
and generations removed from their wild progenitors. The metamorphosis of the rat from
an evil carrier of pestilence to a hero of modern medicine resulted from the work of many
researchers in various locales in the early 1900s. Rat breeding programs were carried out
at a number of institutions and resulted in brand-name rats such as Osborne-Mendel,
Long-Evans, Sprague-Dawley and Wistar. The latter were bred and distributed by the
Institute from 1906 through the 1940s and used in laboratories throughout the world.
Wistar rats comprised a number of strains of Rattus norvegicus, including several inbred
and numerous outbred, or random, strains.16 The Sprague-Dawley strain was started by
Bob Dawley in 1923 from wild rats found in a dump near a meat packing plant.17 Rats
were the first standardized laboratory animals.18
Rats can learn to crave the same drugs as humans, including alcohol, cocaine, nico-
tine and amphetamine, and have been known to overindulge.19 Rats are the preferred
model for the study of genetics of many complex diseases including hypertension, non-
insulin-dependent diabetes, renal disease and autoimmune and behavioral disorders.20
Pharmacokinetic studies at the University of Illinois indicate that rat and human systems
absorb and eliminate a number of drugs at similar rates. Their findings suggest that
testing new drugs on rats and perhaps one other species of animal may satisfy US Food
and Drug Administration (FDA) requirements for preclinical studies.21 The basic internal
structures of rats and humans are similar despite the disparities in length and diameter.
Similarities extend far beyond gross anatomy. Rats even have personalities they can be
sullen or cheerful depending upon their upbringing and circumstances. Surprisingly, rats
are generally sociable, curious and love to be touched.22
Rats!