IACUC Routes of Administration Guidelines

Procedures must have prior approval from the Institutional Animal Care and Use Committee (IACUC). The approved protocol specific to each study should list the route of administration, intervals between substance administration, dose range, and volume to be administered.

When administering substances to laboratory animals, take care to select an appropriate route of administration, method of restraint, dosing interval, and dose volume.

All personnel should be trained to safely perform the selected route of administration. Contact the RAR training staff or veterinary staff for assistance or training.

If you have questions or need training in any of these methods, contact Research Animal Resources (RAR) training staff at rartrain@umn.edu.

On this page, you will find (click to jump to topic):

Definitions
Parenteral Administration
Enteral Administration

Guidelines for Injection/Administration of Substances by Site
Recommended Locations & Approximate Needle Sizes

Definitions

Parenteral: Administering substances outside of the gastrointestinal tract. Routes of parenteral administration:

Intravenous (IV): Administering substances into venous circulation.
Intraperitoneal (IP): Administering substances into the abdominal cavity.
Topical (epicutaneous): Applying substances directly to the skin for topical effect.
Transdermal (percutaneous): Applying substances directly to the skin for systemic effect.
Subcutaneous (SC): Administering substances under the skin (between the skin and muscle layers).
Intradermal (ID): Administering substances into the dermis.
Intramuscular (IM): Administering substances into the muscle.
Intranasal (IN): Administering substances into the nose.Intraosseous (IO): Administering substances into the bone marrow.
Intratracheal (IT): Administering substances within the trachea.
Intracranial: Administering substances into the brain.
Epidural (ED): Administering substances into the epidural space of the spinal cord.
Intrathecal (IT): Administering substances into the subarachnoid space (in the spinal canal but not within the spinal cord).

Enteral: Administering substances into the gastrointestinal tract. Routes of enteral administration:

Per os (PO): Administering substances by mouth.
Gavage: Administering substances via a tube passed through the nose or mouth into the esophagus or stomach.
Rectal: Administering substances into the rectum.

Bolus: Administering a large volume of a substance by injection.

Parenteral Administration

Parenteral administration refers to administering substances outside of the gastrointestinal tract.

Substances administered parenterally should be:

Isotonic (the same concentration of solute as the blood)
Close to physiologic pH (6.8-7.2): If pH is outside of physiologic range, administer the substance through a central vessel (such as the jugular or femoral vein) or buffer the solution so that pH is appropriate.
Sterile and delivered aseptically.
Mixed in a laminar flow hood or biosafety cabinet and filtered through a 0.2 micron filter, if the preparation is not a commercially manufactured solution.

Routes of parenteral administration are listed below.

INTRAVENOUS (IV)

Substances can be administered as a bolus or an infusion:

The maximum bolus injection volume is 1-5 ml/kg. If larger quantities are administered, give as an infusion.
Infusions are often administered with specific equipment such as precision pumps or microdrip infusion sets.

Site selection for venous access is species-specific. Common sites:

Rodents: Lateral tail vein, saphenous vein, or retro-orbital venous sinus. Injection volume for retro-orbital injection is limited to 200 ul and injection sites (ie the eye) should be alternated.
Rabbits: Lateral ear, jugular, or cephalic vein.
Larger species: Jugular, cephalic, femoral, or saphenous vein.

Veterinary staff can recommend refinements to improve animal comfort during repeated IV dosing.

INTRAPERITONEAL (IP)

Injections are administered into the lower right abdominal quadrant. Aspirate before injecting to avoid inadvertent administration into the bladder or gastrointestinal tract.
Repeated daily intraperitoneal dosing for up to one month is well-tolerated in rodents.
Administration of irritating substances may cause ileus (stasis of the gastrointestinal tract) and peritonitis (inflammation of the abdominal cavity).

ADMINISTRATION TO THE SKIN OR MUSCLE

Topical (epicutaneous)

Avoid applying caustic or irritating substances unless you have prior approval on an IACUC protocol.
Apply substances to unbroken, hair-free skin.
Avoid applying substances to sites that animals can reach during grooming.

Transdermal (percutaneous)

Transdermal dosing is typically accomplished by applying a patch impregnated with the substance of interest.
Apply the patch so as to avoid inadvertent ingestion or removal by the animal.
Systemic absorption is not immediate. Apply patches prior to the time of anticipated need according to the manufacturer's instruction.
Do not cut patches to reduce dose size. If an appropriate dose of patch is not commercially available, consider an alternative route of administration or cover the un-needed portion with surgical tape.

Intradermal

Use a small, sharp needle (25-27G).
Tent the skin. Holding the syringe parallel to the animal, direct the needle into the dermis. Aspirate and inject. A “bleb” should be visible if the substance is in the intradermal tissue.
Inadvertent subcutaneous administration is common. Consult RAR veterinary or training staff for assistance.

Subcutaneous (SC)

Tent the skin. Holding the syringe parallel to the animal, direct the needle into the subcutaneous tissue (beneath the skin). Aspirate and inject.
The rate of absorption from the subcutis may be slower than with other parenteral routes.
Subcutaneous infusions can be administered with an oily depot or osmotic mini-pump. Consult veterinary staff for additional information.

Intramuscular (IM)

IM dosing is best used in larger species with greater muscle mass.
In smaller animals, use the gluteal or quadriceps muscles.
In larger animals, use the gluteal, quadriceps, biceps, or epaxial muscles.
Take care to avoid the sciatic nerve, which runs along the caudal aspect of the femur. Inadvertent injection into nerves can result in paralysis and localized muscle necrosis.

Intracranial

Intracranial injections require anesthesia (and stereotactic equipment when appropriate). Injections can be administered through a surgically implanted cerebral cannula, direct injection, or an osmotic pump catheter.
Animals must be heavily sedated or anesthetized for cannula or catheter placement and direct injections.

Epidural (ED) or intrathecal (IT)

Epidural or intrathecal administration of substances requires highly trained personnel. Consult with veterinary staff before attempting this technique.
Animals must be heavily sedated or anesthetized.

Enteral Administration

Enteral administration refers to administering substances into the gastrointestinal tract. Routes of enteral administration are listed below.

Voluntary Consumption

Substances are typically mixed with the daily diet, flavored water, or other palatable items to encourage consumption. Care should be taken to maintain an appropriate daily caloric intake and habituate animals to any novel food items before adding a drug.

Care should be taken to ensure animals consume all agent offered. Laboratory personnel are responsible for ensuring adequate food and water intake.
Food or water containing additives should be clearly labeled and properly disposed of.

Gavage

Gavage is often used to administer an exact PO dose.
Administration of gavage volumes greater than 5 ml/kg may cause distress in species that are unable to vomit such as rodents, rabbits, chinchillas, etc.
The gavage tube size should be appropriate for the species being dosed. Contact veterinary staff for assistance.

Rectal

This technique is not frequently used in laboratory animals. Substances can be administered via an enema or a suppository.

Guidelines for Injection/Administration of Substances by Site

MOUSE

IV bolus: 1-5 ml/kg; less than 0.2 ml total
IV drip: 2-4 ml/kg/hr
IP: 2-3 ml
SC: 2-3 ml in the scruff, 0.2 ml inguinal
ID: <0.05 ml/site
IM: ≤50 microliters/site
IN: <0.02 ml
Gavage: 10 ml/kg
ED: 0.15-0.2 ml/kg
RO: 200 ul

If mice are under 21 days of age, contact RAR for recommended injection volumes

RAT

PO: 5 ml/kg
IV bolus: 1-5 ml/kg
IV drip: 2-4 ml/kg/hr
IP: 10-20 ml/kg
SC: 5-10 ml/kg or 5-10 ml total over 2-4 sites
ID: 0.05-0.1 ml/injection
IM*: 0.1-0.2 ml maximum
IN: 50 ul
Gavage: 1-20 ml/kg
ED**: 0.15-0.2 ml/kg

GUINEA PIG

PO: 5 ml/kg
IV bolus: 1-5 ml/kg
IV drip: 2-4 ml/kg/hr
IP: 1-10 ml/kg
SC: 1-5 ml/kg
ID: 0.05-0.1 ml/injection
IM*: 0.05 ml/kg/site
IN: 0.03-0.05 ml/injection
Gavage: 1-20 ml/kg
ED**: 0.15-0.2 ml/kg