Tutorial Article
The transverse facial venous sinus: an alternative location
for blood collection in the horse
H. A. W ALESBY *, D. J. H ILLMANN ?, J. M. B LACKMER AND J. W ILLIAMS
Departments of Veterinary Clinical Sciences and ?Comparative Biological Sciences, Louisiana State University, School
of Veterinary Medicine, Skip Bertman Drive, Baton Rouge, Louisiana 70803, USA.
Keywords: horse; blood collection; transverse facial vein; venous sinus; phlebotomy
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Introduction
Blood collection in the horse is necessary for a variety of reasons.
The most common site for blood collection in the adult horse is
the jugular vein. Alternative sites for blood collection include the
cephalic, lateral thoracic and medial saphenous veins. Alternative
venipuncture sites are used when the jugular vein is no longer
patent or unavailable due to haematoma formation, septic
thrombophlebitis or focal cellulitis. Alternative blood collection
sites are chosen based on safety, accessibility and patient
temperament. Additionally, a site amenable to serial sampling in
critically ill animals at risk for thrombophlebitis is desirable.
Three veins on the head of the horse form dilations called
sinuses ( Figs 1 and 2). The first is the transverse facial vein,
which runs parallel to the facial crest to form an anastomosis
with the facial vein ventral to the cranial end of the facial crest
(Ashdown and Done 1987; Henry and Haynes 1989;
Constantinescu 1991; Hackett and Sack 2001). The second is
the deep facial vein, which runs 2 cm ventral and parallel to
the transverse facial vein to form a sinus located deep to the
masseter muscle (Ashdown and Done 1987; Henry and
Haynes 1989; Constantinescu 1991; Hackett and Sack 2001).
The third is formed by a dilation of the buccal vein, which
dilates as it passes deep to the masseter muscle (Ashdown and
Done 1987; Henry and Haynes 1989; Constantinescu 1991;
Hackett and Sack 2001). The sinus formed by the dilation of
transverse facial vein is most accessible for venipuncture
(Kemble 1994; Orsini and Kreuder 2002).
Technique
Most horses are remarkably tolerant of this technique.
Adequate restraint can typically be accomplished with a halter
*Author to whom correspondence should be addressed. Presentaddress: Metropolitan Emergency Animal Clinic, 12106 Nebel Street,Rockville, Maryland 20852, USA.
Fig 1: Three veins form dilations called venous sinuses: 1) thetransverse facial vein forms the transverse facial venous sinus;2) the deep facial vein forms the deep facial venous sinus; and3) the buccal vein forms the buccal venous sinus. Of these, thetransverse facial sinus is most accessible for blood collection.
Transverse facial venous sinus
Facial artery Facial vein
Buccalvenoussinus
Deep facialvenous sinus
Fig 2: Latex casts of the venous sinuses (blue) and arteries(pink) demonstrate the anatomic relationship between thevenous sinuses, soft tissues, and bony landmarks of the head.A) dilation of the transverse facial vein; B) dilation of the deepfacial vein; and C) dilation of the buccal vein.
EQUINE VETERINARY EDUCATION / AE / March 2007