BU IACUCInstitutional Animal Care and Use Committee IACUC oversee... Approved November 2008, Revised January 2014, Revised July 2019








Experimental Tumor Models

  1. Injecting tumor cells in rodents, usually mice, is an accepted experimental procedure for the purpose of either propagating a tumor line or for studying various cancers and cancer treatments.
  2. Mutant or genetically engineered mice with predisposition for developing a certain tumor are used in order to study specific cancers.
  3. Chemically induced tumors.

Spontaneous, Naturally Occuring Tumors and Masses

Naturally occurring tumors or masses are also found in laboratory rodents, as well as in other animals, including humans. These may include benign masses such as lipomas (usually benign unless interfering with a physiologic function), but can also be cysts, hematomas, abscesses, or masses of various etiology. Animals being diagnosed with a non-experimental tumor or mass must be evaluated as soon as possible. Depending on the findings and the condition of the animal, the PI may decide to euthanize the animal. If the animal is to be maintained, a monitoring plan must be discussed and approved with the veterinary staff in BU ASCThe Animal Science Center manages and oversees animal-relate.... Humane endpoints, as listed in this policy, are determinants for euthanasia.

Rats and mice sometimes develop tumors as part of their genetic predisposition. Examples of these are mammary tumors in both rats and mice, pituitary tumors in aging Sprague-Dawley rats, and interstitial cell tumors in male Fisher-344 rats. There are many others, most frequently seen as the animal gets older.

Induction of the Animal Cancer Model

Transplantable tumors may be induced orthotopically, in the tissue or site of origin, or ectopically, usually subcutaneously in the flanks or by intravenous injection. Changing the inoculation site may change the growth characteristics of the tumors. Knowledge of the origin, incidence, and time of onset of spontaneously developing tumors in the host animal is necessary if experiments or animal welfare are not to be compromised.3

To promote the engraftment of some experimental tumor lines, it may be necessary to modify the recipient’s immunologic or physiologic status. Low-level whole body irradiation or immunosuppressive agents are frequently used to further suppress the immune response of immunodeficient rodents before inoculation with human tumor xenografts.


  1. The development of immunodeficient mouse models engrafted with human tumors: These animals may be naturally immune suppressed, such as the nude mouse or the SCID mouse, or they may have been made immunosuppressed by irradiation or administration of immunosuppressant agents. Boston University Animal Science Center (BU ASC) recommends barrier housing for these animals whenever possible and monitoring for infectious disease.
  2. Once animals become sick with the tumor it may be necessary to separate them and allow them more space to avoid cannibalism by cage mates. They may require supportive care such as food on the cage floor.
  3. Nursing care may be given as indicated by the animal’s condition and consistent with the research goals.

Humane Endpoint Criteria

Experiments should be completed before tumor development or tumor-associated disease causes death or a significant deterioration in the host.3




BU IACUC Approved November 2008, Revised January 2014
Post-Procedure Monitoring Form