The jugular vein is the most common place to draw blood from a horse; however, this is not always possible. If the jugular vein is damaged or if the horse is no longer tolerant of the procedure, there is an alternative location to draw blood, said Honor Ame Walesby, DVM, MS, Dipl. ACVS, of Louisiana State University, during her presentation at the 2003 American Association of Equine Practitioners' convention. Walesby discussed a technique for safely drawing blood from the facial venous sinus as an alternative to the jugular vein.

The facial venous sinus is found several inches below the eye where the transverse facial vein dilates. "As much as 35 mL of blood can be taken from this sinus," said Walesby. She added that this should provide enough blood for most testing requirements, and this site can be used multiple times in one day.

Walesby drew blood from the jugular vein and the facial venous sinus from 25 horses at Louisiana State University and compared the values for packed cell volume and total plasma protein to see if the blood would yield the same values. No differences were detected, allowing Walesby to conclude that blood from the facial venous sinus would be valid for testing procedures.

"Additionally, venipuncture (puncture of a vein) at this location is well tolerated by the patient," said Walesby. "If the animal is head-shy or difficult to restrain, then adequate control can generally be achieved with a twitch or a lip chain