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The Veterinary Journal 174 (2007) 407–409

TheVeterinary Journal

Short Communication

Anatomical variations in the cephalic and omobrachial veins in the dog

Olga Gomez, Mabel Giner, Jose Terrado *

Departamento de Medicina y Cirugıa Animal, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, Avda Seminario,

s.n. 46113 Moncada-Valencia, Spain

Accepted 1 September 2006

Abstract

In the dog, the blood from the antebrachial part of the cephalic vein is typically drained by three vessels: the axillobrachial, the omo-brachial and the proximal segment of the cephalic vein. In this work, two anatomical variations affecting the omobrachial and the prox-imal part of the cephalic vein in dogs are reported. The bilateral absence of the omobrachial vein was observed in two adult mongrel dogsand the lack of the proximal segment of the cephalic vein in one dog. These differences suggest that a certain degree of variation is normalin the layout of the superficial veins of the thoracic limb in the dog and implies that the blood egress from the cephalic vein in the dog, asin other species, is sometimes accomplished by only two veins.� 2006 Elsevier Ltd. All rights reserved.

Keywords: Omobrachial vein; Vascular anomaly; Dog; Cephalic vein; Anatomical variation

The cephalic vein is the only large superficial vein of thethoracic limb. Given its size and location, it is the favouredsite for venepuncture in the dog. In the forearm, it is crani-ally located, directly under the skin and the superficial fas-cia. The cephalic vein courses along the cranial surface ofthe extensor carpi radialis muscle. Its brachial part subse-quently crosses the cleidobrachial muscle and emits theaxillobrachial vein on the lateral surface of the brachial tri-ceps muscle. The cephalic vein runs proximomedially underthe brachiocephalic muscle and finally enters the externaljugular vein. The axillobrachial vein courses over the lat-eral head of the brachial triceps muscle, passes behindthe humerus and terminates in the axillary vein (Evans,1993).

The omobrachial vein is an anastomosis between theaxillobrachial vein and the external jugular vein, and is acharacteristic of the dog (Nomina Anatomica Veterinaria,2005) and rabbit (Barone, 1996). In the dog, it leaves theaxillobrachial vein and runs superficially on the deltoidmuscle. It then arches cranially, crosses the brachiocephalic

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doi:10.1016/j.tvjl.2006.09.003

* Corresponding author. Tel.: +34 96 1369000; fax: +34 96 1395272.E-mail address: jterrado@uch.ceu.es (J. Terrado).

muscle laterally and enters the lateral surface of the exter-nal jugular vein (Fig. 1A) (Evans, 1993). The omobrachialvein is the only named tributary out of 12 veins draininginto the external jugular vein between its origin at theunion of the linguofacial and maxillary veins and its junc-tion with the superficial cervical and cephalic veins (Stoneand Stewart, 1988).

Two different anatomical variations affecting the cepha-lic and omobrachial veins were observed in three mongreldogs routinely prepared for anatomical dissection throughvascular perfusion of fixative solutions. Firstly, in two dogs(an adult male and an adult female) a bilateral absence ofthe omobrachial vein was observed. The anatomical dissec-tion of these dogs showed the complete absence of theomobrachial vein (Fig. 1B) on both the left and right sides.The cephalic vein in both animals followed its usual course,from the metacarpal region to the external jugular vein. Atits brachial part, the cephalic vein emitted the axillobra-chial vein, which also had its normal course and branches,except the omobrachial vein.

Conversely, in a third dog (a young adult male), theproximal part of the cephalic vein was bilaterally absent.In this dog, the omobrachial vein was large and it received

Fig. 1. Left lateral view of different configurations of the superficial venous system in the shoulder region of the dog. The axillobrachial vein (AV), cephalicvein (CV) and omobrachial vein (OV) are exposed. A: Normal anatomical configuration. B: Dissection of the left aspect of the thoracic limb of a male dogshowing the absence of the omobrachial vein. C: Dissection of the left aspect of the thoracic limb of a male dog with the absence of the proximal part of thecephalic vein. D: Right limb of the same dog. Note the communicating vein in C and D (arrowheads).

408 O. Gomez et al. / The Veterinary Journal 174 (2007) 407–409

tributaries draining the major tubercle of the humerus andthe surrounding muscles which are usually drained by thecephalic vein. In relation to the overall aspect of this ana-tomical region, the omobrachial vein appeared to be a nat-ural continuation of the cephalic vein with the course of theomobrachial vein although it was slightly more distallyplaced (Fig. 1C and D). A vein communicating with thecephalic vein and the omobrachial vein was observed inthis dog, with a small calibre in the left limb (Fig. 1C)

and a larger one on the right-hand side (Fig. 1D). No othervascular malformations or anomalies were detected.

A total absence of named veins in the dog is not fre-quently found in the literature, but some malformationsaffecting veins mostly involving the visceral veins, andsometimes with pathological consequences, are more com-monly described (Harder et al., 2002). The omobrachialvein is usually a large superficial vein which, although var-iable in calibre, has no muscular or visceral tributaries and

O. Gomez et al. / The Veterinary Journal 174 (2007) 407–409 409

which receives only small vessels from the skin and fascia(Evans, 1993). It represents a collateral exit of blood fromthe cephalic vein. As a rule, the blood egress from thecephalic vein to the cranial vena cava is drained in thedog by three pathways: (1) the cephalic-external jugularconnection, (2) the axillobrachial-axillary connection and(3) the omobrachial-external jugular connection. One ofthese routes is absent in the three dogs reported, eitherowing to the absence of the omobrachial vein or to the lackof the proximal part of the cephalic vein.

Absence of the omobrachial vein does not lead to anyreorganisation of other tributaries. However, the lack ofthe proximal part of the cephalic vein consequently forcesits normal tributaries to merge with another close vein,and, in this case, it was the omobrachial vein that playedthis role. As a result of these reorganisations there is a lackof any detectable pathology. In the dog, these differencesmost probably reflect anatomical variations comparableto the normal anatomy of other species. Dogs 1 and 2 weresimilar to other carnivores such as the cat, and dog 3 wascomparable to the rabbit, where the proximal part of thecephalic vein is frequently atrophic (Barone, 1996). Otheranatomical variations concerning muscle insertions havealso been interpreted in this way (Terrado et al., 2005).

Although specific for the dog and rabbit, the omobra-chial vein is always described as a customary vein and wehave been unable to find any previous report in the litera-ture illustrating the absence of either this vein or the prox-imal part of the cephalic vein. Despite this phenomenon

not being previously reported, we believe that the absenceof one of these two veins is probably quite frequent, andwe suggest that they might be regarded as occasionallyabsent structures in the dog. It is probable that the non-existence of associated pathologies may explain why thesevariations are not commonly assessed in most examinationprotocols and necropsies, and their putative absence istherefore not reported.

Acknowledgement

The Fellowship for O. Gomez from the UniversidadCardenal Herrera-CEU is gratefully acknowledged.

References

Barone, R., 1996. Veins. In: Anatomie Comparee des MammiferesDomestiques. Vigot, Paris, France, pp. 449–685.

Evans, H.E., 1993. The veins. In: Miller’s Anatomy of the Dog, third ed.WB Saunders Company, Philadelphia, pp. 682–716.

Harder, M.A., Fowler, D., Pharr, J.D., Tryon, K.A., Shmon, C., 2002.Segmental aplasia of the caudal vena cava in a dog. CanadianVeterinary Journal 43, 365–368.

Nomina Anatomica Veterinaria 2005, Editorial Committee of the WorldAssociation of Veterinary Anatomists, fifth ed., Hannover, Columbia,Gent, Sapporo, p. 98, 119.

Stone, E.A., Stewart, G.J., 1988. Architecture and structure of canineveins with special reference to confluences. The Anatomical Record222, 154–163.

Terrado, J., Giner, M., Gomez, O., 2005. Anomalous insertion of thesplenius muscle in a dog. The Veterinary Journal 170, 375–376.