Jugular veins variation-anatomy review

Frontiers in Veterinary Science 2024

Author

Ryan Appleby
December 04, 2024

Seoyoung Cho , Jupill Chang , Woosuk Kim , Kidong Eom , Jaehwan Kim

Background
The study investigates anatomical variations of the external jugular vein (EJV) in Shih Tzu dogs using computed tomography (CT). The EJV is critical in veterinary procedures, but little is known about its variations in canines. The research aims to classify these variations and assess their clinical implications, particularly in relation to persistent left cranial vena cava (PLCVC).

Methods
This retrospective multicenter study analyzed CT scans from 547 Shih Tzu dogs conducted between 2015 and 2023. Both pre- and post-contrast images were reviewed to identify EJV variants and associated compensatory vascular patterns. Statistical analyses included chi-square tests and correlation assessments.

Results
Five EJV types were classified: normal (Type I), unilateral hypoplasia (Type II), unilateral aplasia (Type III), bilateral hypoplasia (Type IV), and bilateral aplasia (Type V). Variants were found in 21.7% of dogs. Compensatory drainage, primarily through the internal jugular vein, was noted in types II–V. PLCVC was identified in 11.9% of cases, with a significant association with EJV variants.

Limitations
The study’s retrospective design and non-standardized imaging protocols may have introduced variability. Additionally, secondary hypoplasia from previous venipuncture could not be ruled out.

Conclusions
Anatomical variations in the EJV are common in Shih Tzu dogs and are significantly associated with PLCVC. These findings have important implications for diagnostic imaging and interventional procedures. Further studies are recommended to evaluate these variants in other breeds.

Figure 1. Illustrations of the appearance of the external jugular vein variants in Shih Tzu dogs. (A) Schematization of a normal external jugular vein and associated veins: Type I. (B,C) Unilateral external jugular vein hypoplasia with two different tributary patterns: Type II. (B) The left maxillary vein runs medially (the large black arrow) and directly becomes an enlarged IJV (the black arrow), while the left linguofacial vein joins the hypoplastic left EJV (the open arrowheads). On the contrary, the right maxillary and linguofacial veins join the lateral side of the salivary gland and drain into a normal-sized right EJV (the black arrowheads) with an average-sized right IJV (the dashed arrows). (C) The left linguofacial vein runs medially (the large black arrow) and directly becomes an enlarged IJV (the black arrow), while the left maxillary vein joins the hypoplastic left EJV (the open arrowheads). On the contrary, the right maxillary and linguofacial veins join the lateral side of the salivary gland and drain into a normal-sized right EJV (the black arrowheads) with a normal-sized right IJV (the dashed arrows). (D) Unilateral external jugular vein aplasia: Type III. Note the left enlarged IJV (the black arrow). (E) Bilateral external jugular vein hypoplasia: Type IV. Note the bilateral hypoplastic EJV (the open arrowheads) and enlarged IJV (the black arrow). (F) Bilateral external jugular vein aplasia: Type V. Note the convergence of the linguofacial and maxillary veins running medially (the large black arrow) and becoming the enlarged IJV (the black arrow). CrVC, cranial vena cava; RSCV, right subclavian vein; LSCV, left subclavian vein; RMV, right maxillary vein; LMV, left maxillary vein; HVA, hyoid venous arch; RLFV, right linguofacial vein; LLFV, left linguofacial vein; REJV, right external jugular vein; LEJV, left external jugular vein; RIJV, right internal jugular vein; LIJV, left internal jugular vein.

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