Alternative Site for Collecting Blood

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."

She warned that the area could become sore and swollen with multiple collections, and that horses with extreme head shyness might not tolerate the technique.

Walesby prefers the facial venous sinus to other alternative sites for blood collection, such as the lateral thoracic vein, which runs along the lower side of the chest cavity, and the medial saphenous vein, which runs down the inside of the hind leg. The skin over the lateral thoracic vein is highly sensitive and the creation of hematomas in this area due to drawing blood could interfere with the girth and performance. The medial saphenous vein is not easily accessible and could put the person drawing blood at risk of injury from the horse.

Walesby emphasized that the facial venous sinus is safe, easily accessible, and therefore a viable location for blood collection.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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