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GUIDELINES for MONITORING NEW OR UNCHARACTERIZED PHENOTYPES IN GENETICALLY MODIFIED MICE (Posted February 2008)
When mice are genetically modified it is often unknown if the resulting phenotype will produce pain or distress or affect ability to grow and thrive. Therefore, when new genotypes are created, and there is a possibility of anatomical, behavioral or metabolic defects that could cause pain or distress, these animals must be monitored closely. The following parameters are guidelines to consider when monitoring animals with unknown phenotypes, and should be modified according to the specific tissues or body systems that have been affected:
| Age of animals |
Parameter |
Frequency |
Document |
| 0-21 days |
Ability to feed |
Once per day, M-F |
No |
| 8-21 days |
Locomotion/Activity |
Once per day, M-F |
No |
| 8-21 days |
Appearance, grooming, Body condition score |
Once per day, M-F |
No |
| 21 days + |
Body condition score, locomotion/activity, appearance/grooming |
Twice per week, more often if needed |
No |
Pups should be assessed for their ability to gain weight compared to normal controls. Any pups that appear to be runted, thin, or not developing normally should be weighed daily and the weight recorded. If such animals do not show weight gain and appear thin, criteria for humane endpoints should be established in the protocol.
Small animals that gain weight at a slower rate but appear healthy according to above criteria may remain on study.
Criteria for euthanasia should be specified in the protocol, and may include body condition score of 2 or less, decreased ability to move, feed or access water.
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