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HLT-VET42-07 · Lesson 5 · 28 clock hours · lab

Parenteral Administration Skills Lab: SC, IM, and IV Techniques

Objective. Students will correctly prepare syringes with the prescribed volume of sterile saline from vials and ampules and demonstrate SC, IM, and IV catheter placement technique on injection training models, meeting all aseptic and safety standards.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Parenteral Administration: Why Technique Matters

Parenteral routes — subcutaneous (SC), intramuscular (IM), and intravenous (IV) — bypass the gastrointestinal tract and deliver drugs directly into body tissues or the bloodstream. Because absorption is faster and more predictable than oral dosing, errors in volume, site, or asepsis can cause immediate patient harm. Veterinary assistants and technicians are responsible for preparing injections accurately and for using technique that protects both the patient and themselves.

Aseptic Syringe Preparation

Gloves and clean work surface. Always wear exam gloves and work on a clean, disinfected surface. Contamination introduced during preparation can cause local infection or systemic sepsis.

Drawing from a multi-dose vial. Wipe the rubber septum with a fresh alcohol swab and allow it to air-dry for several seconds — do not blow on it or fan it. Draw back the plunger to pull air equal to the volume you need, then insert the needle into the center of the septum and inject that air. Invert the vial, position the needle tip above the fluid level, and draw slightly past your target volume. Remove any air bubbles by tapping the barrel sharply and expelling them before confirming the final volume at the correct calibration line. The tip of the plunger's leading edge (the top edge of the black rubber stopper) aligns with your measurement mark.

Breaking a glass ampule. Score the neck lightly with an ampule file if no pre-scored ring is present. Wrap the neck in a gauze square or alcohol swab before snapping away from your body. Use a filter needle or filter straw to draw fluid, then swap to the appropriate administration needle before injecting — glass particles can otherwise be introduced into the patient.

Drug log documentation. Every drug draw, including sterile saline practice, must be recorded on the simulated drug log: date, time, drug name, concentration, volume drawn, patient name (or model number), and initials. Accuracy in documentation is a legal and professional obligation.

Subcutaneous Injections

SC injections deposit fluid into the loose connective tissue beneath the skin. Common sites in dogs and cats include the dorsal neck and interscapular region. Tent the skin between thumb and forefinger, insert a 22–25 g needle at approximately a 45-degree angle with the bevel up, and advance gently. Aspirate briefly; if blood appears, withdraw and prepare a fresh injection. Inject slowly, release the skin tent, withdraw smoothly, and apply gentle pressure — do not rub, as this can cause local irritation. Volumes appropriate for SC delivery vary by species and site; large volumes can be divided among multiple sites.

Intramuscular Injections

IM injections reach muscle bellies for drugs requiring faster absorption than SC or for irritating solutions that must avoid subcutaneous tissue. In small animals, the epaxial muscles (lumbar) and the semimembranosus/semitendinosus muscles of the caudal thigh are common sites. Insert the needle at a 90-degree angle to the skin surface. Aspiration technique: before injecting, pull back the plunger slightly; if blood is present, the needle tip may be intravascular — withdraw, replace the needle, and redirect. Inject slowly and withdraw in one smooth motion. Rotate sites if repeated injections are required.

Safe Needle Handling

Needlestick injuries are among the most common occupational hazards in veterinary practice. Never recap a needle with two hands. Use the one-hand scoop method: place the cap on a flat surface, slide the needle into the cap using one hand, and then flip the cap upright and press it on with one hand against a firm surface. Immediately dispose of used needles and syringes as a unit into a puncture-resistant, labeled sharps container. Never overfill a sharps container past its marked fill line.

IV Catheter Placement (Cephalic Vein)

Peripheral IV catheters provide reliable venous access for fluid therapy, blood sampling, and drug delivery. The cephalic vein running along the cranial foreleg is a standard site in dogs and cats.

Steps for placement:

1. Gather all supplies before starting: appropriate-gauge over-the-needle catheter, alcohol swab, tape strips, T-port cap, flush syringe of sterile saline.

2. Clip and prep the site if indicated; clean with an alcohol swab and allow to dry.

3. Have a second person occlude the vein proximal to the insertion site (raise the vein).

4. Bevel up, advance the catheter at a low angle (approximately 15–20 degrees) until a flash of blood appears in the hub.

5. Lower the angle slightly and advance the plastic cannula fully off the stylet and into the vein.

6. Release occlusion, withdraw the stylet, and apply gentle digital pressure over the vein tip while capping with the T-port.

7. Flush gently with sterile saline to confirm patency — no swelling (perivascular infiltration) should occur.

8. Secure with tape using a standard "Christmas tree" or "butterfly" taping pattern to prevent dislodgment without occluding flow.

Contamination prevention. Never touch the exposed cannula or the needle hub interior. If the catheter is contaminated at any point, discard it and start fresh with new equipment.

Safety Summary

Passing the competency checklist is your evidence that you can perform these skills safely on a live patient. Precision and discipline during practice on training models directly predicts safety in clinical rotations.

Key terms8

ParenteralAny route of drug administration that bypasses the gastrointestinal tract, including SC, IM, and IV routes.
Aseptic techniqueA set of practices designed to prevent microbial contamination of drugs, equipment, and the patient during preparation and administration.
AspirationThe act of pulling back the syringe plunger before injection to check whether the needle tip is inadvertently positioned inside a blood vessel.
One-hand scoop methodA needle-recapping technique in which the cap is placed on a flat surface and the needle is scooped into it using only one hand, reducing the risk of needlestick injury.
Over-the-needle catheterAn IV catheter consisting of a plastic cannula mounted over a removable metal stylet; once the vein is accessed, the stylet is withdrawn, leaving the flexible cannula in place.
FlashThe visible backflow of blood into the hub of an IV catheter or needle that confirms the tip has entered the lumen of a blood vessel.
Filter needleA needle containing a small filter designed to trap glass particles when drawing fluid from a broken glass ampule.
T-port capA short injection port cap attached to an IV catheter hub to maintain a closed, capped system while allowing periodic access for drug or fluid administration.

Worked examples4

1. The veterinarian orders 1.5 mL of sterile 0.9% NaCl to be drawn into a 3-mL syringe for a practice draw. After drawing, you notice the leading edge of the plunger stopper sits at the 1.7 mL line. How much air (in mL) must you expel to reach the correct volume, and what is the correct volume?
  1. Identify the ordered volume: 1.5 mL.
  2. Identify the current volume in the syringe: 1.7 mL.
  3. Calculate the excess: 1.7 mL − 1.5 mL = 0.2 mL of excess (air and/or fluid).
  4. Point the needle upward, tap the barrel to move air to the tip, and gently push the plunger until the leading edge of the stopper aligns precisely with the 1.5 mL graduation mark, expelling 0.2 mL of air/excess fluid.
Answer: Expel 0.2 mL; the final volume in the syringe should be exactly 1.5 mL, confirmed by the plunger stopper's leading edge at the 1.5 mL line.
2. You are drawing from a multi-dose vial that contains sterile saline. You need 2.4 mL. Before inserting the needle, how much air should you draw into the syringe, and why?
  1. Determine the volume needed: 2.4 mL.
  2. To equalize pressure inside the vial (which is a sealed multi-dose container), draw 2.4 mL of air into the syringe before inserting the needle.
  3. Inject the 2.4 mL of air into the vial after inserting the needle, then invert the vial.
  4. Draw slightly past 2.4 mL, remove air bubbles, and adjust to exactly 2.4 mL before removing the needle.
Answer: Draw 2.4 mL of air into the syringe before inserting it. Injecting this air into the sealed vial equalizes internal pressure, making it easier to withdraw the correct fluid volume.
3. A simulated drug log entry requires you to record the volume drawn from a 10 mL multi-dose vial of sterile 0.9% NaCl (concentration: 0.9 g per 100 mL). You drew 3 mL for one model and 1.5 mL for a second model. What is the total volume documented for that vial on this session, and how many mL remain if the vial started full?
  1. Total volume drawn: 3 mL + 1.5 mL = 4.5 mL.
  2. Starting volume of the vial: 10 mL.
  3. Remaining volume: 10 mL − 4.5 mL = 5.5 mL.
  4. Document on the drug log: date, time, drug name (Sterile 0.9% NaCl), concentration, volumes drawn (3 mL and 1.5 mL), total drawn (4.5 mL), remaining (5.5 mL), model identifiers, and your initials.
Answer: Total volume documented as drawn is 4.5 mL; 5.5 mL remains in the vial.
4. During a simulated IM injection on a training model, you draw 0.8 mL for injection but accidentally draw to 1.1 mL. You expel fluid until the plunger reads 0.9 mL, then expel one more small push and reach 0.8 mL. Verify: did you expel a total of 0.3 mL from the 1.1 mL draw?
  1. Starting volume in syringe: 1.1 mL.
  2. Target volume: 0.8 mL.
  3. Volume to expel: 1.1 mL − 0.8 mL = 0.3 mL.
  4. First expel: 1.1 mL → 0.9 mL = 0.2 mL expelled.
  5. Second expel: 0.9 mL → 0.8 mL = 0.1 mL expelled.
  6. Total expelled: 0.2 mL + 0.1 mL = 0.3 mL. This matches the required correction.
Answer: Yes, a total of 0.3 mL was expelled (0.2 mL + 0.1 mL), correctly bringing the volume from 1.1 mL to the ordered 0.8 mL.

The math in this lesson1

Learners read syringe graduations and expel 0.2 mL to bring a 1.7 mL draw to the 1.5 mL order.
N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Aseptic syringe preparation drill: students practice withdrawing precise volumes of sterile 0.9% NaCl from multi-dose vials and glass ampules, matching calculated volumes from the previous dosage calculation lesson, and documenting each draw on a simulated drug log—instructor checks air bubble removal and volume accuracy · SC and IM injection on foam/gel training models: students perform a minimum of five SC and five IM injections on training models, receiving immediate instructor feedback on angle, bevel orientation, aspiration technique (where appropriate), and safe needle recapping using the one-hand scoop method · IV catheter placement on vascular access training arm (canine model): students practice catheter insertion in the cephalic vein trainer, tape-securing the catheter, flushing with saline, and capping; instructor evaluates technique on a competency checklist
Materials: 3-mL and 6-mL syringes, 22g and 25g needles, SC/IM foam training models, IV access arm trainer (canine), sterile 0.9% NaCl vials, ampule file, alcohol swabs, exam gloves, catheter tape, T-port caps, competency checklist, sharps container
Check: Competency checklist with 15 behavioral anchors (e.g., confirms calculated volume, wears gloves, uses one-hand recap, aspirates before IM injection, secures catheter without contamination); student must pass 14 of 15 items on a single observed attempt; a single repeat attempt is permitted after remediation

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Pharmacology and pharmacy
1. When drawing fluid from a glass ampule, which of the following actions is MOST important to prevent patient harm from glass contamination?
Pharmacology and pharmacy
2. During an IM injection on a training model, you aspirate and observe blood entering the syringe hub. What is the CORRECT next action?
Pharmacology and pharmacy
3. Which needle angle is CORRECT for a subcutaneous injection in a dog?
Occupational safety and health / workplace safety
4. A veterinary assistant recaps a used needle by holding the cap in one hand and placing the needle into it with the other hand. This practice is:
Clinical nursing / patient care
5. After inserting a cephalic IV catheter, you flush with sterile saline and notice swelling forming under the skin at the insertion site. This finding MOST likely indicates:
Veterinary law, ethics, and professional practice
6. When documenting a drug draw on the controlled drug log during this lab, which set of data elements is REQUIRED for each entry?
Pharmacology and pharmacy
7. What is the PRIMARY reason for injecting an equal volume of air into a sealed multi-dose vial before withdrawing fluid?
Professional and program requirements
8. On the competency checklist for this lab, a student must pass at least 14 of 15 behavioral anchors in a single observed attempt. A student passes 13 items on the first attempt. What is the CORRECT next step according to the lab policy?
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