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Maintaining Tumors in Rodents 1
For all studies in which rodents have experimentally induced
or implanted tumors, the expected size, clinical complications
(e.g., ulceration or necrosis), experimental endpoints, and criteria
for intervention or early termination of an animal from the study
must be specified in the protocol for review by the Animal Care
and Use Committee (ACUC).
Generally accepted maximum allowable tumor size for a single
spontaneous or implanted tumor that is visible without imaging
is approximately 2 cm in any dimension in mice and approximately
4 cm in any dimension in rats. Greater single or combined tumor
burdens may be approved by the ACUC with sufficient scientific
justification. Maximum size that a tumor can grow at locations
within the cranium, thoracic cavity, or behind the eye, which
would have to be monitored through imaging, is more limited.
Tumors at these locations may interfere with vital functions
of the animals and result in morbidity or mortality even though
the size may be much less than cited above.
The overall wellbeing of the animal should take priority over
precise tumor measurements in decisions regarding euthanasia
or other interventions. Daily monitoring, including weekends
and holidays, of tumor growth and overall clinical condition
is the required norm.
Common signs of pain and distress in rodents include: ruffled
fur, discharge from the eyes, weight loss, anorexia (lack of
feces in the cage), dehydration, hunched posture, lethargy, reluctance
to move, uncoordinated movements, being cool to touch (hypothermia),
pale ears or feet, labored respiration, and blue-tinged mucous
membranes (cyanosis). Furthermore, animals in pain or distress
may not interact with their cage mates or cage mates may become
aggressive towards them. The affected rodent may become uncharacteristically
aggressive toward a familiar human handling it. Animals may squeal
when picked up or when an affected area is touched. Persistent
vocalization and crying indicates substantial pain or distress.
Animals that exhibit signs described above in the presence of
a tumor burden, or that appear to be dying should be euthanized.
Animal care staff will be instructed to mark such cages and immediately
contact the individual named on the cage card and/or a clinical
veterinarian for evaluation and intervention. Veterinarians will
consult the protocol.
Refer to the ACUC Guidelines for using the ascites method for
Monoclonal Antibody Production for additional information on
ascitic tumors. 2
If you have any questions or need assistance, please consult
ACUC Office staff (443-287-3738) or an RAR veterinarian (410-955-3273
or the veterinarian on clinical call: 5-3713).
IACUC policies and guidelines
are available at www.jhu.edu/animalcare/
References:
1. Approved by the IACUC on: January 17,
2002; revision adopted October 20, 2005.
2.
IACUC policies and guidelines are available at www.jhu.edu/animalcare/ |
