When nursing the sick horse, having a correctly placed intravenous catheter that ensures good venous access is vital. On occasion, massive volumes of intravenous fluids – in excess of 10 litres per hour – are required for treating acute and life-threatening conditions, thus requiring a fully functional catheter.

In horses, the jugular is the largest and most accessible vein for catheter placement. If it cannot be used, the alternatives are the lateral thoracic,cephalic and saphenous veins, but these vessels are smaller, less accessible, and not as robust, so more prone to damage.

Catheters

‘Short-term’ catheters are often made of fluorinated ethylene propylene (FEP) polymers. ‘Long-term’ catheters are made from polyurethane, as they are more likely to maintain the integrity of the vein without causing complications.

The use of polyurethane catheters should now be accepted as the norm when treating the critically ill patient. Many have been adapted and manufactured specifically for use in the horse (Figure 1).

Figure 1: A variety of IV catheters for use in horses

A full list of materials needed to perform intravenous catheterisation is given in Table 1.

Jugular catheter placement technique

There follows a step-by-step guide to simple ‘over-the-needle’ catheter insertion.

1.   Clip an area in the jugular groove, in the cranial third of the neck. Clip it large enough so that the person inserting the catheter is less likely to inadvertently break sterility. If relevant, braid the mane to keep it out of the catheter site.

2.   Don the exam gloves and prepare the site aseptically using the sterile swabs and surgical scrub.

3.   Inject a subcutaneous ‘bleb’ of local anaesthetic exactly over the jugular vein where the catheter is to be inserted (Figure 2). Continue with the surgical scrub.

Figure 2: Injecting a 'bleb’ of local anaesthetic

4.   Set up a sterile tray that contains the catheter, suture and injection cap. Position it within reach of the user but at a safe distance away from the horse, so that it cannot become contaminated.

5.   Don the sterile gloves and remove the protective sheath from the catheter. Loosen the stylet from the catheter and make sure only the hub is touched.

6.   Distend the jugular vein with one hand and, holding the catheter in the other hand, position it with the tip pointing downward, just over the bleb of local anaesthetic. The catheter should be held parallel to the jugular vein (Figure 3).

Figure 3: Positioning the catheter for insertion

7.   With the bevel of the stylet facing you, insert the catheter into the skin at a 45° angle. Continue steadily advancing the catheter until blood is visible in the hub. Angle the catheter slightly more parallel to the vein (without dragging it against the neck) and advance the catheter and stylet together about one centimetre. If blood continues to rise in the hub, the catheter is well within the lumen of the vein.

8.   Grasp the stylet with the hand that had raised the vein, and using the ‘clean’ hand, slide the catheter off the stylet. The stylet must remain fixed in place while the catheter is slid down into the vein. The catheter should run smoothly and without resistance into the vein. Now remove the stylet.

9.   Screw on the extension set and/or catheter cap.

10.   Flush the catheter with heparinised saline and draw back to check that blood is aspirated into the syringe.

11.   Using the suture, stitch the catheter (and extension set if used) in place, taking care to keep the catheter seated parallel to the vein within the jugular grove. The extension set should be secured with a loop left in the tubing, so that when it is handled, there is no pull on the catheter.

Maintenance and prevention of complications

Examine the catheter site at least three times a day for the presence of heat, pain, swelling or discharge around the insertion area. Check for venous patency at the same time, raise the vein and make sure it fills the full length of the neck. Palpate the entire vein, feeling for thickening, especially in the region where the catheter tip is located.

Intravenous catheters must be flushed with 10 ml of heparinised saline at least twice daily as well as before and after every injection of a drug. Catheter patency should be checked when it is flushed and prior to the injection of a drug.

To check patency, a heparinised saline syringe is attached and aspirated, ensuring there is a free flow of blood back into the syringe. If no ‘flashback’ is seen, the catheter must be checked for clots, kinks or a loosely attached extension set or injection cap. The way a horse holds its head can lead to a ‘positional’ catheter, that is, one that only intermittently allows fluids to flow freely. It may require re-suturing to restore patency.

Injection caps need to be replaced daily, and sometimes more often, depending on how often a needle is inserted in a given time period. They should also be wiped with an alcohol swab prior to any injections.

Cover the whole site if it is exposed to dirt and dust. A large sized Tubigrip works well as the use of bandaging tape can pull on a catheter (Figure 4).

Figure 4: Neck cover on a foal

Complications

Sometimes, despite all the preventive measures taken, complications occur, and these need prompt recognition and appropriate nursing care.

Thrombophlebitis

This is a very serious condition which can result in the jugular vein becoming occluded. The jugular is responsible for venous return from the head and if this condition becomes permanent, it can cause
distortion of the normal appearance of the head.

At least one jugular must remain patent throughout the horse’s life, so this situation should be of grave concern to the owner and veterinary team. Serious head oedema may also result, which can lead to upper respiratory obstruction.

Localised cellulitis

This is invariably the consequence of inappropriate aseptic preparation.

Trauma

Self trauma is not uncommon. Foals are especially adept at removing catheters with their hind feet. Catheters can easily get caught on water buckets, be traumatised when a horse is allowed to hang its head over a stable door or rub against a wall (Figure 5).

Figure 5: Trauma to catheters and fluid lines isn't always self inflicted!

Catheter embolism

This is when the catheter breaks off from the hub owing to inadvertent trauma, or is sliced off when inserted incorrectly. Thoracic radiographs or ultrasonography can be used to locate the loose catheter. Catheters that lodge in the lung usually do not cause any long-term problems

‘Long-term' catheters

Catheters placed using the Seldinger technique with a ‘guide wire’ play an important role in equine critical care nursing (Figure 6). They are available in longer lengths, with multiple lumens, and for long-term use (up to four weeks).

Figure 6: Intravenous long-term catheter being placed in a lateral thoracic vein, using the Seldinger technique

These catheters are used for administration of total parental nutrition (TPN) and/or continuous rate infusions (CRI) of drugs (Figure 7).

Figure 7: Mare receiving TPN, replacement fluids and drugs by CRI

Author

Bonny Millar

CVT (USA) RVN REVN

Bonny is senior vice-president of the BVNA and an REVN at Rossdales Equine Hospital in Newmarket. She lectures, teaches and writes regularly about equine nursing and has a particular interest in wound management and critical care nursing.

• VOL 25 • No2 • February 2010 • Veterinary Nursing Journal