Basic Services|Animal Import


Introduction of new strains from outside sources holds the greatest risk to established colonies. With the increased exchange of animals between academic institutions the risk becomes intensified because health status, health monitoring and maintenance programs may vary widely between institutions.
A program of incoming rodent quarantine (isolation) seeks to minimize the risk to WIS colonies by excluding specific pathogens, determining the actual health status of incoming animals at the time of arrival, exclude unhealthy animals, identify animals more suitable for rederivation than introduction and thereby protect the health of WIS colonies in general.


Contacts: Import TeamCarmit Rozenberg-Katzav

Ordering instructions

Detailed ordering instructions are provided in a short tutorial, demonstrating how to fill-in and submit a request for Animal Import/Export

Import request

Introduction of new animal strains to Weizmann has to be approved for both ethics and health issues.

  • You must have an IACUC approved protocol under which these animals will be studied.
  • Researchers can check the Weizmann Strains Database for available strains.
  • To order animals from approved vendors (i.e. Envigo or Jackson only) see instructions under Animal Ordering.
  • To import animals from others then approved vendors (including collaborators) complete the import/collaboration request online through:
    Internal Services > Animal Import.

Take care to fill in the following fields:

  • Complete strain name
  • Destination in the Weizmann Institute (name of animal facility)
  • Origin: Provide the affiliation (name of University / Institute) of your collaborator
  • Collaborator’s (Sender) contact information

The import process

Flow chart describing the animal import process. Details are given below.

  • Import request: By submitting the application, the sender institution contacts will receive automatic email with the details of the request and the information they should provide the WIS Import Team, including appropriate health reports and documentation.
  • Health status: The health reports will be reviewed by WIS veterinarians. According to their health status, incoming animals will be assigned to isolation period or rederivation. Rederivation by caesarean-section, or recovery of fresh or cryopreserved embryos or sperm, will be carried out in the quarantine unit, the isolators or the transgenic facility according to health status. In case animals do not meet WIS health standard for import, the researcher will be notified by email.
  • Shipping: The Import Team will coordinate the shipping of the approved animals, and will notify the investigator via email upon their arrival to the institute. On occasion, the outside (sending) institution may not furnish the requested information, or Veterinary Resources may requested further clarification. Please note that this may delay processing. New strains are imported as live animals or frozen sperm or embryos. Frozen embryos are shipped in a liquid nitrogen dry shipper. Frozen sperm may be shipped in a dry shipper or on dry ice. Fresh blastocyst stage embryos may also be imported for immediate embryo transfer upon receipt. This requires a high level of coordination in advance between the shipping and receiving facilities.
  • Isolation & rederivation: All rodents from sources that are not approved vendors must undergo a period of quarantine (isolation) and testing before being admitted to the WIS animal facilities. Please plan your imports accordingly.

Isolation period

Imported animals will be allowed to enter one of WIS Animal Facilities after appropriate isolation period and testing.

  • During isolation period the imported animals are housed with contact sentinels inside an isolator for at least 6 weeks.
  • After 6 weeks the sentinels are tested by the Diagnostic and Quality Assurance Laboratory. Health status is obtained within additional 3-6 weeks.
  • At the end of the isolation period the animals will be transferred by Veterinary Resources staff to the facility/room indicated on the import request. WIS PI will by notified via email.


Animals from infected colonies may be accepted for rederivation only. The rederivation process removes adventitious organisms such as viruses, bacteria and parasites from the animals. The rederived animals meet SPF health status and no longer threats the health of other established animal colonies.

  • Imported animals are housed in a dedicated quarantine facility in breeding pairs. Alternatively, embryos or sperm (for IVF) can be imported.
  • Embryo transfer (ET): pre-implantation stage embryos are isolated from the reproductive tract of one mouse (donor female) and transferred to the reproductive tract of a mouse (recipient female; surrogate mother) of known health status made pseudopregnant in order to allow implantation, gestation, and birth.
  • Caesarean-section (c-section / hysterectomy): at E19 the uterine horns (of the donor female) are exteriorized and cut open. The pups are removed and stimulated until they are breathing. The pups are then transferred to a foster mother (recipient female) of known health status.
  • At the age of 6 weeks, one pup and the surrogate/foster mother are tested by the Diagnostic and Quality Assurance Laboratory. Health status is obtained within additional 3-6 weeks.
  • Rederivation by C-section is less efficient relative to ET, and often several cycles are requited before new colony is established.

Risks: Success of recovery depends chiefly on the quality of the material that we receive. If it has not been frozen well, then we will not be able to recover live animals. In our experience if the embryo/sperm we receive is good, then the line can be reconstituted. It is advisable to check provider what quality control has been carried out on the shipped material, and to request at least to straws of frozen material.