Which animal may have blood drawn from the orbital plexus?

Which animal may have blood drawn from the orbital plexus?

• A. Sheep
• B. Pigeon
• C. Gerbil
• D. Rat

Answer: (D)

Blood from the orbital plexus refers to retro-orbital sinus sampling, a method used in small laboratory animals to obtain venous blood from a network behind the eye. The rat has a well-defined orbital sinus that is large enough to access safely with proper technique, making it the classic species for this site in LAT practice. Sheep and pigeons rely on more standard veins like the jugular or wing veins, and their orbital regions aren’t used for routine blood collection. Gerbils aren’t the typical choice for this method in standard labs, so the rat is the best answer.

Blood from the orbital plexus refers to retro-orbital sinus sampling, a method used in small laboratory animals to obtain venous blood from a network behind the eye. The rat has a well-defined orbital sinus that is large enough to access safely with proper technique, making it the classic species for this site in LAT practice. Sheep and pigeons rely on more standard veins like the jugular or wing veins, and their orbital regions aren’t used for routine blood collection. Gerbils aren’t the typical choice for this method in standard labs, so the rat is the best answer.