Policy on Tumor Production.
It is the policy of the Case IACUC to require that each project involving
tumor production in rodents define a set of conditions under which
the affected animals will be euthanized. Use of survival time as an
end point is rarely justifiable and should be avoided. Animals should
be euthanized before their tumor burden becomes excessive and before
the animals become debilitated. Four general criteria for euthanasia
are given:
- Maximal tumor size should be limited to 10% of
body weight. Mice which have subcutaneous or skin
tumors should be humanely euthanized when the tumor
reaches 1.5 centimeters in diameter. Rats should
be euthanized if the tumor size exceeds four centimeters
in diameter. All animals should also be euthanized
if a tumor ulcerates prior to reaching this size.
- In some studies, either the tumor itself or anti-tumor
therapies may cause the animal to lose condition.
In these studies, adult animals should normally be
euthanized if adult animals lose 20% of their original
body weight, or if growing animals attain a weight
less than 80% of untreated controls.
- Some tumors, depending on type and location, may
interfere with the function of vital organs, such
as the lungs or digestive tract. If animals are seen
to be in distress (e.g. labored breathing) due to
an experimentally induced tumor, they should be euthanized
regardless of the size of the tumor or the weight
of the animal.
In addition, some tumors may interfere with locomotion, making it
difficult for the animal to reach food or water. If the animal is
unable to eat or drink, it should be euthanized.
Animals in which tumors have been induced should be checked at least
three times weekly - either by the principal investigator or his/her
designee. Animals that fall into any of the three categories listed
above should be reported to the principal investigator. The principal
investigator will examine the animal and take appropriate steps within
24 hours of receiving such a report.
In the case of very rapidly growing tumors or other situations in
which the progression of clinical signs is likely to be rapid, the
principal investigator or his/her staff should examine the animals
daily.
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