Laboratory TechniquesLaboratory Techniques

LAT Chapter 3LAT Chapter 3

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Chapter 3

Injection TechniquesInjection Techniques

• Injections with needles and syringes used to administer various substances

• Syringe construction and sizes

• Considerations for blood withdrawal

• Proper disposable of needles

and syringes

• Common routes of injection

Chapter 3

• IM generally given in hind legs. Most desirable site is large muscle mass (e.g.,

quadricep muscle group).

Alternative site: muscles posterior to femur

• Do not inject too much material.

Intramuscular Injection (IM)Intramuscular Injection (IM)

Chapter 3

• Given in lower right quadrant of abdomen. Avoid bladder and cecum.

• Slight resistance may be encountered.

• Aspirate prior to injection. Yellow fluid: needle could be in bladder

Greenish fluid: needle could be in intestine or cecum

Blood: may have entered blood vessel

Intraperitoneal Injection (IP)Intraperitoneal Injection (IP)

Chapter 3

• Given into the thick dermal skin layer.

• 25 gauge needle typically used.

• Needle directed at 20 to 30 degree angle into skin.

• Only small quantity of fluid can be injected.

0.1 to 0.2 ml

Intradermal Injection (ID)Intradermal Injection (ID)

Chapter 3

• Placed in the more vascular space between skin and underlying muscle

• Large area of subcutaneous tissue exposed by raising a tent of skin

• Entering the injection site => + then 0 resistance

• Precautions - puncture hand, inj. out other side

Subcutaneous InjectionSubcutaneous Injection

Chapter 3

• IV access sites in common laboratory animals

• Site preparation - disinfect

• Use pressure to distend the vessel.

• Insert needle at 30 degree angle to skin.

• Removing the needle - apply pressure

Intravenous Injection (IV)Intravenous Injection (IV)

Chapter 3

• Used as aid to diagnose disease Collection site and amount determined by species

and test type.

• Intravenous Technique Technique basically same as intravenous injection

Blood Collection TechniquesBlood Collection Techniques

Chapter 3

• Auricular artery frequently used for blood collection in rabbit. Artery easily visible.

Large quantities of blood can be obtained.

• Same technique as intravenous

• Apply pressure to artery after needle withdrawal.

Blood Collection - IntraarterialBlood Collection - Intraarterial

Chapter 3

• Used for animals that do not have large veins.

• Limited to rodents with large venous sinus or plexus posterior to the eye.

• Animals typically under anesthesia.

• Allow punctured vessel to clot and then place ophthalmic ointment into the eye.

Blood Collection - Retro-OrbitalBlood Collection - Retro-Orbital

Chapter 3

• To collect small samples from rodents• Blood collected from saphenous vein into a

capillary tube• Anesthesia not required• Multiple samples collected in same day

Blood Collection - SaphenousBlood Collection - Saphenous

Chapter 3

• Withdraw blood slowly• Dangerous procedure

Must use general anesthesia Will be fatal in some animals Animal typically euthanized after procedure

Blood Collection - Blood Collection - CardiacCardiac Puncture Puncture•Needle placed through chest wall and into heart

Chapter 3

• Method used to collect of several drops of blood from mice or rats.

• Method is controversial.• Justification for use may be required.• Anesthesia recommended for animals older

than weaning age.

Blood Collection - Tail TransectionBlood Collection - Tail Transection

Chapter 3

• Total Blood Volume = 6% of Body Weight Varies depending on

species, age, sex, etc.

• Guideline used when sampling frequently Volume equal to no more

than 1% of an animal’s body weight can be taken every two weeks

Example: 3kg rabbit = 30ml of blood

Blood VolumeBlood Volume

Chapter 3

• Most often used for rodents Gavage tube attached to

hypodermic syringe• Hold animal in proper position• Insert tube at approximately

45 degree angle Do not force tube

• Withdraw and start again if resistance is met while inserting the tube

Gastric Gastric Intubation Intubation (Gavage)(Gavage)

Chapter 3

• Commonly used in larger animals.• Use gag to prevent chewing of tube.• Slight resistance may be encountered when

inserting tube. Avoid entry into the trachea; delivery into lungs will

likely cause death.

• Guinea pig and chinchilla - palatal ostium

Gastric Intubation (Gavage) (cont.)Gastric Intubation (Gavage) (cont.)

Chapter 3Additional ReadingAdditional Reading

1. Crow, S.E. and Walshaw, S.O. Management of Clinical Procedures in the Dog and Cat. 2nd. Edition. Lippincott-Raven. New York, NY, 1997.

2. McCurnin, D.M. Clinical Textbook for Veterinary Technicians. 3rd Edition. W.B. Saunders. Philadelphia, PA, 1994.