Copyright 2004, University of Minnesota Board of Regents.
The University of Minnesota is an equal opportunity educator
for Immunization of Research Animals
While a variety of adjuvants
are available for use in research animals, Freund's adjuvant is perhaps
the most commonly used. Complete Freund's adjuvant (CFA) may cause inflammation,
induration, pain and necrosis at the injection site in mammals. Despite
the common perception that CFA is a superior adjuvant, numerous studies
have demonstrated comparable results with less irritating adjuvants.
It is important to note that complications are still possible with other
adjuvants, as well.
In order to eliminate or
reduce discomfort from Complete Freund's adjuvant, the following guidelines
have been established by the IACUC. Departures from these guidelines require
adequate scientific justification on your Animal Care and Use Protocol form for approval
by the IACUC.
- The use of other adjuvants must
- CFA may be used only for the
first (priming) dose. Subsequent immunizations should be with incomplete
Freund's or another adjuvant unless justified. This is rarely warranted
and if allowed, an interval of at least three weeks should be given between
Because of the potential
for complications from certain routes of administration of immunizations,
the following guidelines have been established.
The inoculum should be free
of extraneous microbial contamination. Millipore filtration of the antigen
before mixing with the adjuvant is recommended when possible.
Injection sites should be cleaned
to remove debris that may result in contamination and infection.
Injections containing Freund's
complete adjuvant should be given subcutaneous (SQ), rather than intradermal
(ID), intramuscular (IM), intravenous (IV) or intraperitoneal (IP). ID
injections frequently result in skin necrosis and sloughing. IM injections
can result in temporary or permanent lameness. IV injections can cause
pulmonary lipid embolism.
For subcutaneous injections,
the inoculum containing the adjuvant should be divided into fractions so
that no more than 0.1 ml is injected per site for rabbits and 0.05 ml per
site for mice. If skin necrosis results while following these guidelines,
future injections should be spaced farther apart.
The IACUC discourages injection
of foot pads because animals may develop chronic pain and secondary infections
in the inflamed areas. If this procedure is to be used, it must be described
and its use scientifically justified, including documentation that injections
in other sites do not produce adequate antibody titers for the specific
antigen being used. If used, only one hind foot may be injected with a
maximum volume of 0.05 ml per site, and injections must be spaced at 10
day to 2 week intervals. Animals that have received foot pad injections
must be housed on contact bedding rather than a metal mesh floor.
The IACUC has not established
guidelines for immunization of birds. Complete Freund's Adjuvant
does not seem to result in the same types of lesions as in mammals.
However, investigators still must specify the details of the immunization
procedure in the Animal Usage Form. In addition, investigators should
be aware that the IACUC may request changes in immunization protocols if
they result in abscess formation or other painful lesions in birds.
The information contained in this site is intended as
a reference for University of Minnesota investigators, and animal husbandry
and veterinary staff. Drug information and dosages are derived from a variety
of sources and do not necessarily guarantee safety or efficacy. Information
obtained through this site should not be relied upon as professional veterinary
advice. Any medications administered or procedures performed on animals
should only be performed by or under order of a qualified, licensed veterinarian.