Common routes of drug administration to laboratory animals include:

1. Gastrointestinal

   1. Oral (per os) - through the mouth

   2. Gavage - into the stomach via a tube or gavage needle

   3. Rectal (per rectum) - into the rectum via the anus

   4. NPO (nil per os) - nothing by mouth. Usually prescribed prior to general anesthesia.

    

2. Parenteral

   1. Intravenous (IV) - directly into the venous bloodstream

   2. Intraperitoneal (IP) - into the abdominal cavity

   3. Subcutaneous (SC) - under the skin

   4. Intramuscular (IM) - into a muscle

   5. Intradermal (ID) - into or between layers of skin

   6. Intrathecal (IT) - into the subarachnoid space of the spinal cord

   7. Intracranial (IC) - into the substance of the brain

   The route selected for drug administration is governed by the nature of the agent being administered, the animal, the purpose of administration, and other factors. The techniques for each route vary from species to species, but all require a general understanding of local anatomy at the injection site.
   
   The investigator should know the physiological properties of the substance to be injected because considerable tissue damage and discomfort can be caused by irritating vehicles or drugs. For example, the rabbit foot pad should not be used as an injection site; sodium pentobarbital should be administered only intravenously or intraperitoneally, not subcutaneously or intramuscularly, because of its irritating properties.
   
   The following tables provide basic information on injection techniques, needle size, and recommended injection volumes for common laboratory animals. If you require additional information training/instruction or reference sources, please call DLAR Veterinary Services at 681-6792.

    NEEDLE SIZES AND RECOMMENDED INJECTION VOLUMES

   SPECIES	Intravenous	Intraperitoneal	Intramuscular	Subcutaneous
   Mouse	Lateral tail vein; 0.2 ml; ~ 25 ga	2-3 ml; ~ 25 ga	NR  Quadriceps/posterior thigh, 0.05 ml; ~ 25 ga	Scruff; 2-3 ml; ~20 ga
   Rat	Lateral tail vein; 0.5 ml; ~ 23 ga	5-10 ml; ~ 21 ga	NR Quadriceps/posterior thigh; 0.3 ml; ~23-25 ga	Scruff; 5-10 ml; ~ 20 ga
   Hamster	Femoral / jugular vein (cut down); 0.3 ml; ~ 25 ga	3-4 ml; ~21 ga	NR Quadriceps/posterior thigh; 0.1 ml; ~ 25 ga	Scruff; 3-4 ml; ~ 20 ga
   Guinea Pig	Ear vein, saphenous vein; 0.5 ml; ~ 23 ga	10-15 ml; ~ 21 ga	Quadriceps/posterior thigh; 0.3 ml; ~ 21 ga	Scruff; 5-10 ml; ~ 20 ga
   Rabbit	Marginal ear vein; 1-5 ml (slowly); ~21 ga	50-100 ml; ~ 20 ga	Quadriceps/posterior thigh, lumbar muscles; 0.5-1 ml; ~ 20 ga	Scruff, flank; 30-50 ml; ~ 20 ga
   Cat	Cephalic vein, 2-5 ml (slowly); ~21 ga	50-100 ml; ~ 20 ga	Quadriceps/posterior thigh; 1 ml; ~ 20 ga	Scruff, back; 50-100 ml; ~20 ga
   Dog	Cephalic vein; 10-15 ml (slowly); ~ 21 ga	100-200 ml; ~ 18 ga	Quadriceps/posterior thigh; 2-5 ml; ~ 20 ga	Scruff, back; 100-200 ml; ~ 20 ga
   Primate(squirrel or owl monkey, galago)	Femoral vein; 0.5-1 ml (slowly); ~ 21 ga	10-15 ml; ~ 21 ga	Quadriceps/posterior thigh; 0.3-0.5 ml; ~ 21 ga	Scruff, 5-10 ml, £ 20 ga

   Primate* (Rhesus, cyno, or Snow)	Cephalic, recurrent tarsal, or jugular veins; 5-10 ml (slowly); ~ 20 ga	25-50 ml; ~ 20 ga	Quadriceps/ posterior thigh, triceps; 1-3 ml; ~ 20 ga	Scruff; 10-30 ml; ~ 20 ga
   Primate*(baboon)	Cephalic, recurrent tarsal, and jugular veins; 10-20 ml (slowly); ~ 20 ga	50-100 ml; ~ 18 ga	Quadriceps/ posterior thigh, triceps; 1-3 ml; ~ 20 ga	Scruff, 10-30 ml per site; 60-100 total; ~ 20 ga

    * Must be chemically restrained

    NR = Not recommended.  Requires extreme care.

   IV INJECTION SITES

   SITE	SPECIES
   Jugular vein	Cat, sheep, dog, goat, rabbit, horse, cow
   Cephalic vein (Fore limb)	Dog, cat, large primates
   Saphenous vein (Hind limb)	Monkey, dog, guinea pig (difficult)
   Tail vein	Rat, mouse
   Marginal ear vein	Rabbit, pig
   Alar vein (Wing vein)	Bird
   Femoral vein	Monkey, cat