How to Place Intravenous Catheters in the Foal

Intravenous catheterization is often necessary to aid in the administration of medications and fluid in the field. The most common intravenous catheters used in foals are the rigid Teflon or less rigid polyurethane over-the-needle catheters. These catheters typical come in lengths ranging from 5cm (2 inches) to 13 cm (5.25 inches). Generally speaking rigid catheters tend to have a short “life span” in the equine neonate because of the tendency to kink, break at the hub and they are more irritating to the vein (Teflon is the much more irritating that the polyurethane). The “over the wire” flexible polyurethane catheters are much less irritating and some of them are antimicrobial coated. This ability of antimicrobial coating to prevent the formation of biofilm may not result in a clinically beneficial effect for the first week of catheterization since the risk of colonization and infection of uncoated catheters is also low during this period. Only when the expected duration of catheterization is beyond 7 to 10 days will the patient realize a benefit from an antimicrobial coated IV catheter. Most of the “over the wire” polyurethane catheters are available in a 16cm to 20cm in length and are available in several gauges. The author uses the 16-guage catheters (which are actually 17Ga internal diameter) for use in all foals < 3 month of age. This size catheter can handle large volumes of fluids that we use on our foals. The 20cm length catheter is when properly placed will be situated very close the right atrium and therefore can be utilized to obtain estimations of the central venous pressures in critically ill neonates. Several different companies current make overthe-wire catheters.a,b Sedation is usually required to facilitate placement of the “over the wire” catheter. Most of our “over the wire” catheters are placed with the patient in lateral recumbency in our sick neonates. Depending on the stability of the patient 0.1 – 0.15 mg/kg of Diazepam IV may be administered for compromised foals and usually gives the veterinarian about a 10 -15 minute window to place the IV catheter. For less compromised foals then the use of xylazine may be warranted at a dose of 0.25 to 0.5 mg/kg IV. These sedatives should be more than adequate to facilitate placement of the IV catheter. A towel is often placed over the head to minimize external stimulation. At times a rolled towel may be utilized on the side of the neck that is down in order to help with visualization of the jugular vein. […]