Anesthesia techniques for mice (for abdominal cercarial exposure)

 

Author Fred Lewis and Yung-san Liang

Introduction

Sometimes mice must be anesthetized for exposure to cercariae. Abdominal skin is most often used for cercarial exposure, especially for exposure to S. japonicum, but sometimes to S. mansoni as well.  Drugs commonly used for anesthesia are ketamine/xylazine, or a sodium pentobarbital solution.

Equipment

Adjustable micropipette (200 µl +)

Electric animal clippers

4” x 4” gauze pads

 

Materials and reagents

Ketamine (90-120 mg/kg BW)/xylazine (10 mg/kg BW)

  or

Sodium pentobarbital solution (50 mg/kg)

Aged tap water

Procedure

·         Inject the appropriate amount of anesthetic intraperitoneally (IP) to anesthetize the mouse for 20-40 minutes.

·         Shave the abdomen with animal clippers.

·         Wipe the shaved abdomen with a 4” x 4” gauze moistened with aged tap water.

·         Apply a pre-determined number of cercariae with the micropipette to the shaved skin and leave for a minimum of 15 minutes (longer if the mouse is still immobilized).

Follow-up comments/recommendations

Abdominal cercarial application is a common technique for mouse exposures, particularly when using S. japonicum cercariae, due to their very sticky nature and behavior, as well as the difficulty of manipulating the cercariae with a pipette. Caution should be exercised when choosing the proper bedding for the mice, since softwood chips contain oils that inhibit cercarial penetration.

 

References

Lewis, F.A., Stirewalt, M.A., Souza, C.P., and Gazzinelli, G. 1986. Large-scale laboratory maintenance of Schistosoma mansoni, with observations on three schistosome/snail host combinations. Journal of Parasitology 72: 813-829.

 

Lewis, F. A. 1999. Schistosomiasis, in Current Protocols in Immunology, John Wiley and Sons, Inc., (R. Coico, Ed) Vol III, 19.1.1 – 19.1.28.