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Institutional Animal Care and Use Committee

Guideline #18

Tumor Burdens in Animals

Although these standards refer specifically to rats and mice, they are applicable to any tumor bearing animal. The standards are as follows:

  • The maximum tumor burden on any one animal should not exceed an estimated 10% of the animal's body weight.
  • The maximum measurable total tumor burden on any one animal should not exceed one solitary mass of 1.5 centimeters in diameter on a mouse or 2 centimeters on a rat.
  • Multiple masses with a combined total diameter of 1.5 cm for mice and 2 cm for rats are permitted.
  • Fluid neoplasia (e.g. hybridomas) and nonneoplastic ascites are addressed under hybridoma production standards.

If an investigator requires tumor burdens larger than those specified above, or requires generation of partially necrotic or ulcerated tumors, a written scientific justification must be submitted to and approved by the IACUC prior to implementation.

LAST REVIEWED AND ADOPTED BY THE IACUC: July 21, 2011