Guideline #18

Tumor Burdens in Animals

1. References:

1.1 Institutional Animal Care and Use Committee Considerations Regarding the Use of Virus-Induced Carcinogenesis and Oncolytic Viral Models. Stephanie D. Lewis, Judy M. Hickman-Davis, Valerie K. Bergdall. ILAR Journal, Volume 57, Issue 1, 2016, Published: 31 March 2016

1.2 The Guide for the Care and use of Laboratory Animals: Eighth Edition. Nation Research Council. Chapter 2, pp.27-28.

2. Purpose/Scope: The purpose of this policy is to provide information to principle investigators who may request to develop tumors in an animal model. The primary focus is tumor burdens in mice and rats, but this policy also applies to all species.

3. External tumors

3.1 The maximum tumor burden on any one animal should not exceed an estimated 10% of the animal's body weight.

3.2 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.

3.3 Multiple masses with a combined total diameter of 1.5 cm for mice and 2 cm for rats are permitted.

3.4 Ulceration, infection or necrosis of a tumor must be monitoring criteria on the AMP (Animal Monitoring Plan). Without active veterinary oversight and treatment, ulcerations, infection or necrosis is considered an endpoint and euthanasia would be the intervention.

3.5 Location: Tumors should be placed in a site or sites that will not interfere with normal body functions such as ambulation, eating, drinking, defecations and/or urination. Tumor placement that interferes with mobility that might prevent the animal from adequately reaching food and water should be avoided. If the placement needs to be near a limb (e.g., in the inner flank region or lower chest wall) ambulation must be a monitoring criteria on the AMP (Animal Monitoring Plan). Intervention, such as euthanasia, must occur if ambulation is impaired, regardless of tumor size.

3.6 Additional endpoint criteria for external tumor growth includes, but is not limited to: respiratory difficulty, a decrease in body condition score (BCS) by one score, a weakened or moribund state, painful response when the tumor is palpated, signs of anemia (paleness, jaundice).

3.6.1 Reference for body condition scoring in mice.

3.7 Monitoring of tumor development must be observed and documented no less than three times per week until a palpable tumor is present. At that point daily monitoring is to occur (including weekends and holidays).

4. Internal tumors

4.1. Monitoring of tumor development and overall animal health must be observed and documented no less than three times per week until a palpable tumor is present. At that point daily monitoring is to occur (including weekends and holidays).

4.2. Monitoring criteria should include, but is not limited to: overall appearance, body condition score, appetite, activity, and respiration.

4.3. Endpoint criteria for internal tumor growth includes, but is not limited to: respiratory difficulty, a decrease in BCS by one score, a weakened or moribund state, and signs of anemia (paleness, jaundice).

5. Any deviation from the criteria listed in paragraphs 3 & 4 above must be justified and approved by the IACUC committee prior to tumor development.

6. Fluid neoplasia (e.g. hybridomas) and nonneoplastic ascites are addressed under hybridoma production standards.

LAST REVIEWED AND ADOPTED BY THE IACUC: February 1, 2024