Animal Care & Nursing Subscriber guide

IV Catheter Placement and Maintenance: Peripheral, Central and Intraosseous Access

Animal Care and Nursing (D5 C, G; K34) 11 min read, 2,556 words Last verified

How technicians place, secure, flush and troubleshoot IV catheters, from the cephalic vein to Seldinger jugular lines and intraosseous access, with the complications the VTNE asks about.

Introduction

An intravenous (IV) catheter is a soft plastic tube left in a vein so fluids, drugs and blood products can be given without a new needle stick each time. Placing and caring for catheters is daily technician work in every hospital ward, surgery suite and emergency room. Good technique decides whether a catheter lasts its full useful life or fails early with swelling, phlebitis or dislodgement.

This guide covers peripheral over-the-needle placement, catheter sizes, taping and labelling, flushing, the main complications, jugular central lines placed by the Seldinger (guidewire) technique, and intraosseous access. The VTNE content outline lists "Perform nursing procedures and maintenance of prescribed treatments (including but not limited to catheterization, wound management, and bandaging)" and "Administer medications via the appropriate routes" as Domain 5 tasks.1

Key facts

  • The cephalic vein is the most common first choice for IV access in dogs and cats.7
  • In a UK multicenter study, 26.7% of peripheral catheters had a complication; suspected phlebitis or limb swelling (11.5%) and dislodgement (7.9%) were the most common.3
  • More than one placement attempt raised the odds of a complication about 2.5 times.3
  • Flush with 0.9% sodium chloride or heparinized saline at least every 24 hours on a regular schedule; do not flush with lactated Ringer's (compound sodium lactate).3
  • In healthy dogs, 0.9% sodium chloride kept jugular central lines patent as well as 10 IU/mL heparinized saline for 72 hours.5
  • A central venous catheter (CVC) enters the external jugular vein and its tip sits in the cranial vena cava, just cranial to the right atrium.612
  • Intraosseous (IO) sites: proximal humerus (greater tubercle), femur (intertrochanteric fossa) and tibial tuberosity.7

How the VTNE tests this

  • Choose the site or size: pick a vein or catheter gauge for a named species and body size (Domain 5 Task C; K34).1
  • Recognize the complication: a stem describes swelling, heat, pain or a fluid line that has stopped, and asks what is happening and what to do first.
  • Order the steps: placement, taping and flushing sequences, including when to stop raising the vein.
  • Know the alternatives: when an IO catheter or jugular line is used, and which drugs should not go IO.
  • Calculate: units of heparin in a flush, or flush schedules over a set time (Domain 5 Task G).1

Core concepts

Parts of an over-the-needle catheter

The common peripheral catheter is an over-the-needle type. A sharp metal stylet runs inside a plastic catheter, with the stylet tip just past the catheter tip. Blood entering the stylet shows in the clear flashback chamber at the back. Once the catheter is in the vein, it is slid forward off the stylet, and the stylet is removed.2 Figure 1 labels the parts.

Labelled diagram of an over-the-needle IV catheter Stylet grip Flashback chamber Catheter hub Plastic catheter (stays in vein) Stylet tip (bevel up)
Figure 1. Over-the-needle catheter. The stylet tip leads into the vein; blood in the flashback chamber confirms entry, then only the plastic catheter is advanced. Original diagram, VTNE Exam Prep, labels based on the University of Bristol clinical skills guide.

Peripheral versus central

A peripheral catheter sits in a limb, ear or pedal vein. A central venous catheter is long and relatively large bore and runs through the external jugular vein into the cranial vena cava. It allows central venous pressure measurement, repeated blood sampling and delivery of hyperosmolar fluids or irritating drugs.12 Saphenous central lines are also used; their tip is measured to the last rib so it lies in the caudal vena cava.6

Phlebitis, extravasation and colonization

Phlebitis is inflammation of the vein. It can be mechanical, chemical or infectious, and left untreated can lead to infection or a thrombus (clot).2 Researchers grade it with the Visual Infusion Phlebitis (VIP) scale from 0 to 5; pain, redness, swelling, a hard vein or fever at a score of 2 or more counts as an inflammatory complication.4 Extravasation is leakage of a drug from the vein into surrounding tissue. Irritants cause inflammation; vesicants such as doxorubicin and the vinca alkaloids can cause tissue necrosis.9 Bacterial colonization of peripheral catheters has been reported at 7% to 20%.2

Catheter types: site, main use and typical complication
CatheterUsual siteMain useWatch for
Peripheral over-the-needleCephalic; lateral saphenous (dog); medial saphenous (cat)Fluids, drugs, anesthesia inductionPhlebitis, swelling, dislodgement
Auricular (ear vein)Ear edge, in large-eared dogs and rabbitsAnesthetized patients when limbs are drapedHard to secure; poor in hypothermic or poorly perfused patients
Central venous (multilumen)External jugular to cranial vena cavaCVP, frequent sampling, hyperosmolar fluidsMalposition, thrombosis, infection
IntraosseousProximal humerus, femur (trochanteric fossa), tibial tuberosityEmergency access when no vein is availableLeak into tissue if bone is fractured; nerve or muscle trauma

Source: Yoquelet 2022 (Today's Veterinary Nurse); Bruno et al. 2026; Haskey et al. 2025.7123

Procedure or technique

Placing a peripheral cephalic catheter

  1. Prepare everything first. Cut two strips of tape long enough to pass about one and a half times around the leg, and pre-flush the T-port or cap with sterile saline so no air is pushed into the vein.2
  2. Clip and prep. Clip the hair at the site and scrub per hospital protocol; chlorhexidine and alcohol are both commonly used.2 For limb catheters, clip about 2 inches above and below the site and all the way around the leg.7
  3. Restraint. The assistant stabilizes the limb and raises (occludes) the vein.2
  4. Insert. Stabilize the vein with your thumb beside it, outside the sterile area. Hold the catheter bevel up at about 30 degrees and enter skin and vein in one confident movement.2
  5. See the flash, then flatten. When blood appears in the flashback chamber, lower the angle and advance about 5 mm more so the catheter tip is well inside the vein.2
  6. Thread off the stylet. Hold the stylet still and push only the catheter forward until the hub meets the skin.2
  7. Release the vein, remove the stylet into a sharps container, and attach the cap or T-port while still holding the limb.2
  8. Tape. Wipe the skin clean and dry. The first strip goes under the hub and around the leg, then over the top; do not cover the catheter-to-cap joint. A second strip secures the cap or T-port.2 Tape firmly but not tightly: tape that is too tight causes swelling as the limb fills after fluids.7
  9. Test. Flush with sterile saline. It should flush easily with no swelling under the skin before you loop and tape the T-port and bandage.2
  10. Label and record. Note the date, time, gauge, vein and who placed it on the bandage and in the record, following hospital policy. A study that tracked catheters recorded these details to judge indwell time and complications.3

If the catheter touches hair, the table or a glove before it enters the vein, it is contaminated and a new sterile catheter is needed. A small skin nick with a No. 11 blade helps in thick-skinned dogs such as bulldogs.2

Daily care bundle

  • Flush on a fixed schedule, at least every 24 hours. In the UK study the most common schedules were every 4, 6 or 12 hours.3
  • Wipe injection ports with alcohol before each use.6
  • Unwrap and inspect the site for heat, redness, swelling, pain and discharge; keep toes exposed under limb bandages so you can check for swelling.7
  • Remove the catheter as soon as it is no longer needed to reduce the chance of bloodstream infection.6

Replacement. Practice varies. Current CDC guidance for adult humans still suggests replacing peripheral catheters every 72 to 96 hours, while human studies found that replacing them only when clinically indicated was safe. In one study of dogs, phlebitis scores rose with time in place, and an indwelling time of 36 hours or more was linked to a higher risk of complications.4 Follow your hospital protocol, and remove any catheter that shows signs of a problem.

Central line by the Seldinger technique

In the Seldinger technique, a guidewire is passed through a needle into the vein, and the catheter is then fed over the wire. The steps below follow a published technician protocol.6

  1. Measure from the insertion site to the thoracic inlet so the tip will lie just cranial to the right atrium.6
  2. Wide clip with a #40 blade, sterile scrub, sterile gloves and drape. Flush and cap every lumen with 0.9% NaCl first.6
  3. Insert the introducer needle (or a short over-the-needle catheter) bevel up, toward the heart. At the flash, feed the J-tipped guidewire about two-thirds to three-quarters of its length.6
  4. Remove the needle while holding the wire. Thread the dilator over the wire with a twisting motion, then remove it.6
  5. Thread the catheter over the wire until the wire exits the distal port, advance to the measured length, then pull out the wire.6
  6. Aspirate and flush each port, suture, cover with a nonadherent pad and transparent dressing, and take a lateral radiograph to check the tip.6

Never let go of the wire. Easy blood aspiration does not prove correct placement; chest radiography is the standard check, and a tip in the right atrium risks arrhythmia and perforation.12

Four steps of the Seldinger technique for a jugular central line 1. Needle in veinlook for flash 2. J-wire throughneedle; remove needle 3. Dilator overwire, then remove 4. Catheter overwire; pull wire out Vein shown as two lines; dashed line is the guidewire. Keep hold of the wire at every step. Confirm tip position by radiograph.
Figure 2. Seldinger technique. A thin wire is placed first, the tract is widened with a dilator, and the catheter follows the wire; the wire is held at all times so it cannot be lost into the vein. Original diagram, VTNE Exam Prep, based on the dvm360 placement steps.

Intraosseous access

An IO catheter goes into the marrow cavity of a bone when a venous catheter cannot be placed. Most drugs that can be given IV can be given IO; the exceptions are drugs toxic to marrow, such as sodium bicarbonate, chemotherapy drugs and large amounts of hypertonic saline. Placement is sterile, fractures in the limb must be ruled out first, and two-view radiographs confirm the position.7 In CPR, the drug route priority is central IV, peripheral IV, intraosseous, then intratracheal.14 Battery-powered and spring-powered insertion devices exist; in a cadaver study, novice students placed IO catheters in the proximal lateral humerus and proximal medial tibia.8

Catheter complications: what the technician sees and does
ProblemWhat you seeTechnician action
PhlebitisPain, redness, swelling, hard vein, feverReport; catheter is usually removed and a new one placed at a different site
ExtravasationSwelling, discomfort at the site during infusion or flushingStop the infusion and alert the veterinarian; vesicants need prompt treatment
OcclusionWill not flush or aspirate; pump alarmsCheck clamps, kinks and tape; do not force the flush
DislodgementCatheter backed out, chewed or missingCheck the length removed is intact; replace

Source: Crisi et al. 2022; Haskey et al. 2025; Martens et al. 2025; Okafor et al. 2026.43911

Flowchart: catheter not flushing

A catheter that will not flush is a common ward problem. Work from the outside in, starting with the simplest cause. The study by Okafor and colleagues defined a successful catheter as one that flushes without extravasation or discomfort, which is the standard you are checking against.11

Decision tree for a catheter that will not flush Flush meets resistance Clamp closed, line kinked, orlimb flexed at the catheter? YesOpen, straighten,retry gently No Tape too tight, or swellingof the toes below the site? YesRe-tape looser,recheck flush No Swelling, pain or leak at thesite when you flush? YesStop. Report;plan removal No Still occluded: do not force the flush.Tell the veterinarian; replace at a new site.
Figure 3. Troubleshooting a catheter that will not flush. Each yes branch ends in an action; forcing a blocked catheter risks pushing a clot into the vein or rupturing the vessel. Original diagram, VTNE Exam Prep.

Species differences

  • Dogs: in the UK study, 82.8% of dog catheters were in the main cephalic vein, and 20 gauge (56.0%) and 22 gauge (35.0%) were the most used sizes.3 The lateral saphenous vein is larger than the medial saphenous in dogs.7
  • Cats: 89.5% of cat catheters were in the main cephalic vein and 93.0% were 22 gauge.3 In cats the medial saphenous vein is larger and easier to catheterize than the lateral.7 In an emergency room study, a visible vein and an operator with more than 500 prior placements most improved first-attempt success.11
  • Puppies and kittens under 12 weeks: the cephalic vein was used in 90.4% of puppies and 78.8% of kittens, and 22 gauge was the most used size. Jugular catheters may be preferred under about 1.2 kg in puppies and 0.3 kg in kittens.10
  • Horses: jugular catheters are standard. Thrombi have been reported with prolonged jugular catheter placement and infusion of irritating drugs.13
  • Rabbits and large-eared dogs: the auricular (ear) vein can be used. It is very superficial, so avoid puncturing through the pinna.7
  • Birds and small mammals: IO sites include the distal ulna and proximal tibia in birds, and the wing of the ilium and ischium in small mammals.7

Calculation

Worked example: heparin in a flush schedule. A jugular catheter is flushed with 3 mL of heparinized saline at 10 IU/mL every 6 hours for 72 hours (the protocol tested by Vose and colleagues).5 How many flushes, and how many units of heparin in total?

Flushes: 72 h ÷ 6 h per flush = 12 flushes (hours cancel).

Heparin per flush: 3 mL × 10 IU/mL = 30 IU (mL cancels).

Total: 12 flushes × 30 IU per flush = 360 IU.

The 3 mL volume is chosen for the example. Always use the volume and concentration on the hospital protocol or the veterinarian's order.

  • Stylets and needles go straight into a sharps container; recap the catheter only in its hard protective cap.2
  • Use aseptic technique for every IV catheter.7 A contaminated catheter is discarded, not wiped.2
  • Chemotherapy extravasation can cause necrosis. Most events in one study happened during the first four treatments, so watch new patients closely.9
  • Client education: explain that a shaved patch and a small bandage are normal after discharge, and that swelling, redness or discharge at an old catheter site should be reported.
  • Check your state practice act for which catheter procedures a credentialed technician may perform; some steps, such as enlarging the skin entry with a scalpel blade, are listed for credentialed technicians or veterinarians only.6

Common mistakes and exam traps

  • Advancing the stylet with the catheter. Only the plastic catheter moves forward; the stylet stays still.2
  • Covering the hub-to-cap joint with tape, so the cap cannot be changed without pulling the catheter.2
  • Flushing with lactated Ringer's. It was linked with higher odds of complications; use 0.9% NaCl or heparinized saline.3
  • Assuming good blood return proves a central line is in the right place. Radiography is the standard check.12
  • Giving sodium bicarbonate or chemotherapy drugs IO.7
  • Repeated attempts in the same patient. Each extra attempt and each extra catheter raised complication odds.3

Quick review

  1. Cephalic vein first in dogs and cats.
  2. Bevel up, about 30 degrees, then flatten and advance about 5 mm after the flash.
  3. Advance the catheter off a still stylet.
  4. Pre-flush caps and T-ports so no air enters the vein.
  5. Tape firm, not tight; keep toes visible.
  6. Flush with 0.9% NaCl or heparinized saline at least every 24 hours; never LRS.
  7. Phlebitis: pain, redness, swelling, hard vein, fever.
  8. Extravasation: drug leaks into tissue; vesicants cause necrosis.
  9. Seldinger: needle, wire, dilator, catheter; never let go of the wire.
  10. Jugular CVC tip just cranial to the right atrium; confirm by radiograph.
  11. IO sites: proximal humerus, femur trochanteric fossa, tibial tuberosity; rule out fracture.
  12. Remove any catheter as soon as it is no longer needed.

Test yourself

5 questions written for this guide. Pick an answer, then check it.

Question 1A cat has had a cephalic catheter for 40 hours. On morning checks the technician finds the site warm and swollen, and the cat pulls away when the catheter is flushed. What is the best action?

Show answer

Answer: C. Stop using the catheter and report it so it can be removed

Heat, swelling and pain at the site are signs of phlebitis or extravasation; the catheter should not be used, and the veterinarian is told so it can be removed and replaced at a new site. A: forcing a flush into an inflamed or leaking site adds tissue injury. B: tight bandaging causes swelling and hides the problem. D: lactated Ringer's as a flush was linked with more complications.

Source Crisi et al. 2022, Inflammatory, mechanical and infectious complications associated with PIVCs, Vet Sci

Question 2Which solution should NOT be used for routine flushing of a peripheral IV catheter, based on a 2025 multicenter study?

Show answer

Answer: A. Lactated Ringer's (compound sodium lactate)

Haskey and colleagues found compound sodium lactate flushes had higher odds of complication and recommended 0.9% NaCl or heparin saline. B, C and D are all 0.9% sodium chloride based, the recommended flush.

Source Haskey et al. 2025, Placement, management and complications associated with PIVC use in UK small animal practice, J Small Anim Pract

Question 3A catheter is flushed with 2 mL of heparinized saline containing 10 IU/mL every 4 hours. How many units of heparin does the patient receive in 24 hours from flushes?

Show answer

Answer: D. 120 IU

24 h divided by 4 h = 6 flushes. 2 mL times 10 IU/mL = 20 IU per flush. 6 times 20 IU = 120 IU. A is one flush only. B uses 3 flushes. C uses 4 flushes.

Source Vose et al. 2019, Heparinized saline vs 0.9% sodium chloride for CVC patency in dogs, PeerJ

Question 4Which sequence matches the Seldinger technique for placing a jugular central venous catheter?

Show answer

Answer: B. Needle, guidewire, dilator, catheter

The needle enters the vein, the J-tipped guidewire is fed through it, the needle is removed, a dilator widens the tract over the wire, and the catheter is threaded over the wire before the wire is withdrawn. The other orders place the catheter or dilator without a wire to follow, or put the wire in before vein access.

Source Central venous catheter placement and maintenance, dvm360

Question 5A collapsed puppy has an intraosseous catheter in the proximal humerus because no vein could be found. Which drug should NOT be given through this catheter?

Show answer

Answer: C. Sodium bicarbonate

Most IV drugs can be given IO, but drugs toxic to bone marrow, such as sodium bicarbonate, chemotherapy agents and large amounts of hypertonic saline, are exceptions. Epinephrine and isotonic fluids are routinely given IO in resuscitation. Dextrose fluids are not on the listed exceptions.

Source Yoquelet 2022, Uncommon IV catheter sites in small animals, Today's Veterinary Nurse

0 of 5 answered

Practise this topic

17 questions from the practice bank are linked to this guide. Answer them in practice mode with instant explanations.

Practise these 17 questions Practise the whole domain

Figure credits

  • Figure 1 Original diagram, VTNE Exam Prep
  • Figure 2 Original diagram, VTNE Exam Prep
  • Figure 3 Original diagram, VTNE Exam Prep

References

  1. AAVSB. Veterinary Technician National Examination (VTNE) Content Outline, approved March 2023. aavsb.org (accessed 2026-10-31). aavsb.org/wp-content/uploads/2025/04/AAVSB-2023-Veterinary-Technician-National-Examination-Content-Outline-2.pdf
  2. University of Bristol Clinical Skills Lab. IV Catheter Placement (CSL_A06). bristol.ac.uk (accessed 2026-10-31). bristol.ac.uk/media-library/sites/vetscience/documents/clinical-skills/IV%20Catheter%20Placement.pdf
  3. Haskey E, Maund V, Allerton F, Browse B, et al. Placement, management and complications associated with peripheral intravenous catheter use in UK small animal practice. J Small Anim Pract. 2025. PMC11736090 pmc.ncbi.nlm.nih.gov/articles/PMC11736090/
  4. Crisi PE, De Santis F, Aste G, Tiscar PG, et al. Inflammatory, mechanical and infectious complications associated with peripheral intravenous catheters in dogs and cats: a risk factor analysis. Vet Sci. 2022;9(3):118. PMC8954030 pmc.ncbi.nlm.nih.gov/articles/PMC8954030/
  5. Vose J, Odunayo A, Price JM, Daves M, et al. Comparison of heparinized saline and 0.9% sodium chloride for maintaining central venous catheter patency in healthy dogs. PeerJ. 2019;7:e7072. PMC6546076 pmc.ncbi.nlm.nih.gov/articles/PMC6546076/
  6. dvm360. Central venous catheter placement and maintenance. dvm360.com (accessed 2026-10-31). dvm360.com/view/central-venous-catheter-placement-and-maintenance
  7. Yoquelet RA. Uncommon IV catheter sites in small animals. Today's Veterinary Nurse. Winter 2023. todaysveterinarynurse.com (accessed 2026-10-31). todaysveterinarynurse.com/emergency-medicine-critical-care/uncommon-iv-catheter-sites-in-small-animals/
  8. Uzan OC, Guieu LS, Hall KE, Tucker CD, et al. Comparison of placement characteristics using two intraosseous devices in canine and feline cadavers by novice users. Front Vet Sci. 2023;10:1196284. PMC10397382 pmc.ncbi.nlm.nih.gov/articles/PMC10397382/
  9. Martens E, Hritz R, Clifford C, Mullin C, et al. A retrospective study of chemotherapy-related extravasation events in dogs and cats. J Vet Intern Med. 2025. PMC11937848 pmc.ncbi.nlm.nih.gov/articles/PMC11937848/
  10. Zilberfarb AL, Odunayo A, Garudadri P, Allen-Durrance A, Okafor C. The cephalic vein is readily accessible for vascular access in pediatric patients less than 12 weeks presenting to an emergency room. Front Vet Sci. 2025;12:1495039. PMC11965629 pmc.ncbi.nlm.nih.gov/articles/PMC11965629/
  11. Okafor CC, Sumners L, Chunn B, Jupiter A, et al. Effect of vein characteristics and operator experience on intravenous catheter insertion success in cats in an emergency room. J Feline Med Surg. 2026. PMC13187352 pmc.ncbi.nlm.nih.gov/articles/PMC13187352/
  12. Bruno B, Degiovanni A, Savarino P, Borrelli A, et al. Point-of-care ultrasonography for verification of central venous catheter placement in cats and dogs. Front Vet Sci. 2026. PMC12975491 pmc.ncbi.nlm.nih.gov/articles/PMC12975491/
  13. Merck Veterinary Manual. Pathological Thrombosis in Animals. merckvetmanual.com (accessed 2026-10-31). merckvetmanual.com/circulatory-system/hemostatic-disorders/pathological-thrombosis-in-animals
  14. Merck Veterinary Manual. Cardiopulmonary Resuscitation of Small Animals. merckvetmanual.com (accessed 2026-10-31). merckvetmanual.com/emergency-medicine-and-critical-care/specific-diagnostics-and-therapy/cardiopulmonary-resuscitation-in-animals

Spotted an error? Email support@vtneexam.com and we will check it against the sources.