A Method of Injecting Small Laboratory Animals by the Ophthalmic Plexus Route ∗

Abstract

Discussion and summary

A method is described of injecting small laboratory animals by a venous plexus in the orbital cavity. This plexus, when entered with reasonable care, facilitates the introduction of materials into the circulation rapidly and without leakage. The tissues surrounding the area of the eye heal rapidly and the eyesight of the animal is not impaired.

Over 100 mice and 50 hamsters were injected in this laboratory and the success of the plexus route suggested it could be utilized in other mammalian species such as rats and guinea pigs. Rats required more manipulation and orientation of the needle than mice or hamsters, but once the plexus was located, no difficulty was encountered in introducing physiological saline (1.5 ml). In the case of the guinea pigs, injections were made directly through the nictitating membrane because of the difficulty in extruding the eyeball. However, the ledge of the sphenoid bone was easily located, thus allowing injection of saline.