Table 2: Branches of the splenic vein in the goat, ruminants, sheep and camel.

Table 3: Branches of the right ruminal vein in the goat and ruminants.

Table 4: Origin of the epiploic branch in the goat, sheep and ruminants.

Table 5: Branches of the reticular vein in the goat and ruminants.

Table 6: Branches of the left gastric vein in the goat and ruminants.

Table 7: Branches of the left ruminal vein in the goat and ruminants.

Table 8: Branches of the accessory reticular vein in the goat.

Table 9: Branches of the left gastroepiploic vein in the goat and ruminants.

Table 10: Origin of the gastroduodenal vein in the goat, sheep, ox, ruminants and camel.

Table 11: Branches of the gastroduodenal vein in the goat, ruminants and camel.

Table 12: Branches of the right gastric vein in the goat, ruminants and camel.

Table 13: Branches of the right gastroepiploic vein in the goat and ruminants.

Table 14: Branches of the cranial mesenteric vein in the goat, ruminants and camel.

Table 15: Number of the jejunal veins in the goat and camel.

Table 16: Branches of the ileocolic vein in the goat and ruminants.

Table 17: Origin of the common trunk for colic branches and right colic veins in the goat, ruminants and camel.

Table 18: Origin of the caecal vein in the goat, ruminants and camel.

Table 19: Branches of the caecal vein in the goat, ox and camel.

Table 20: Branches of the caudal mesenteric vein of the goat, ruminants and camel.

Table 21: Origin of the middle colic vein in the goat, ruminants, ox and camel.

Table 22: Origin of the sigmoid veins in the goat.

textbooks were collected either via hard copies or electronic search. The pattern of the external roots of the portal vein in the goat, sheep, ox, and camel was reviewed, organized and discussed.

Results and Discussion

The main extrahepatic branches of the portal vein are the splenic, cranial mesenteric and gastroduodenal in the goat, ruminants and camel. The right ruminal vein originates from the splenic vein and it gives off either the right ventral coronary vein as well as the ventral, dorsal and deep ruminal branches in the goat or it gives off the ventral and dorsal branches only in the goat and ruminants. The reticular vein originates from the splenic vein and gives off the ruminal, reticular and deep branches in the goat or it gives off small branches to the ruminal atrium, cardiac orifice and the adjacent portion of the dorsal ruminal sac in the goat and ruminants. The epiploic branch arises either from the splenic vein in the goat, sheep and ruminants or from the right ruminal vein in the goat. The left ruminal vein originates either from the splenic in the goat and ruminants or from the left gastric vein in the goat. Furthermore, the left ruminal vein detaches the ventral, dorsal and deep ruminal branches in the goat.

The left gastric vein originates from the splenic vein in the goat and ruminants and it gives off the accessory reticular and left gastroepiploic veins as well as the omasal and omasoabomasal branches in the goat and ruminants. The left gastric vein terminates as a parietal and a visceral omasoabomasal branch in the goat. The accessory reticular vein originates from the left gastric vein and it detaches an omasal branch and continued to the diaphragmatic surface of the reticulum in the goat. The left gastroepiploic vein detaches the reticular, omasal, abomasal, omasoabomasal, and omental branches in the goat while, it detaches epiploic branches to drain the omentum and gastric branches to drain the omasum and abomasum in the goat and ruminants.

The gastroduodenal vein arises from the portal vein in the goat, sheep, ruminants, ox and camel, while, it arises also from the splenic vein in the camel. The cranial pancreaticoduodenal, right gastric and right gastroepiploic veins originate from gastroduodenal vein in the goat, ruminants and camel. The right gastric vein gives off the abomasal, duodenal and omental branches in the goat and ruminants while, the right gastric vein drains the lesser curvatures of the omasum, abomasum and the reticulum in the camel. Furthermore, the right gastroepiploic vein gives off the abomasal, omental and duodenal and omental branches in the goat and ruminants.

The cranial mesenteric vein detaches the caudal duodenal, jejunal, ileal, ileocolic and caudal mesenteric veins or it gives off the caudal pancreaticoduodenal and caudal mesenteric veins then it divides into the jejunal, right colic and ileocolic veins or the cranial mesenteric detaches the caudal pancreaticoduodenal, jejunal, ileal, ileocolic and right colic veins in the goat. The cranial mesenteric vein detaches the caudal mesenteric vein then it terminates by dividing into the ileocolic, right colic and ileal veins in ruminants. However, the cranial mesenteric vein gives off the jejunal and caudal mesenteric veins in the camel. The number of the jejunal veins is either from 24-27 or 17-18 or 18-22 in the goat, while they are 5 jejunal veins in the camel.

The ileocolic vein gives off the common trunk for both colic branches and right colic veins, mesenteric ileal vein, small caecal veins and ileal vein or it gives off the colic branches, right colic veins and caecal vein in the goat, while the ileocolic vein detaches the common trunk for the colic branches and right colic veins as well as the caecal and ileal veins in the ruminants. However, the right colic vein arises also directly from the cranial mesenteric vein in the ruminants and camel, while it originates also from the caudal mesenteric vein in the camel.

The caecal vein is considered as the direct continuation of the ileocolic vein in the goat and camel. However, the caecal vein arises from the ileocolic vein in the goat, ruminants and camel, while the caecal vein arises also from the ileocecal vein in the camel. The caecal vein gives off the caecal and antimesenteric ileal branches in the goat, ox and camel. Furthermore, the caecal vein terminates as the antimesenteric ileal vein in the goat and ruminates, while the caecal vein terminates as a small branch on the free border of the jejunum in the camel.

The caudal mesenteric vein gives off the middle colic vein, and then it passes along the descending colon as the left colic vein, which detaches the sigmoid veins and terminates as the cranial rectal vein in the goat and ruminates. On the other hand, the caudal mesenteric vein gives off the left colic and cranial rectal veins in the camel. The middle colic vein arises from the caudal mesenteric vein in the goat, ruminants and camel. However, the middle colic vein originates from the right colic vein in the camel, while it originates from the cranial mesenteric vein in the ox.

The left colic vein is the direct continuation of the caudal mesenteric vein the goat and ruminants, while it arises from the caudal mesenteric vein in the goat. However, the caudal mesenteric vein becomes the left colic vein after giving off the right colic vein in the camel. The sigmoid veins arise from either the left vein or the caudal mesenteric veins in the goat. The left colic vein continues as the cranial rectal vein in the goat, ruminants and camel. However, the cranial rectal vein originates directly from the caudal mesenteric vein in the goat and camel.

Conclusion

Variation in the extrahepatic branches of the portal vein is very common in small and large ruminants. It is important to emphasize the possible variations of the extrahepatic branches of the portal vein to veterinary surgeons, as it may have implications for imaging studies and surgical interferences of the liver in ruminants.

Acknowledgments

The author is thankful to the technical staff and lab-assistants in the Veterinary Anatomy Department for their support and help.

Author Contribution

The author collected the data, carried out the research, wrote, and revised the review paper.

Conflict of interest

The author declared no conflicts of interest

References