Protocols for field and laboratory rodent studies - HAL

3- Identifying rodents● Head and body length:Figure 33: “Head and body”, and tail measurements (Photo: Herbreteau V.)- Place the animal lying on its back, in a straight position, without stretching the body (Fig. 33A).- Use pins to mark the landmarks of the body on the dissection board. Place one pin on the tip of the noseand a second one on the side of the anus. For males, lift the scrotum up to see the anus before placingthe pin.- Then remove the animal and measure precisely the distances between the pins with a ruler (Fig. 33B).● Tail:- Place the animal lying on its back, with the tail in a straight position (Fig. 33A). Place one pin on the side ofthe anus and a second one on the tip of the tail. Do not include terminal hairs, if present, but measure theirlength separately (in the case of squirrels, etc.).- Verify that the tail has not been cut at its extremity: insuch case, the tail looks like intact but its extremity issquare (the tail length would be a little shorter and it mayresult in a wrong identification). If the tail is cut ordamaged, indicate, “cut” when recording data, and add inbrackets the length of the cut tail (it can be useful foridentifying the species of the animal).● Hind-foot (or pes) length:- Position the ruler on the dissection board and flattenthe hind-foot on it or directly flatten the ruler underthe hind-foot.- Measure the distance between the back of the heeland the tip of the central toe, without including theclaw (Fig. 34).● Ear:- Introduce the ruler (with the extremity starting at “0”)into the ear and measure the distance between thenotch (at the base of the ear) and the extremity of theear (Fig. 35).- Verify that the ear is not cut or damaged at theextremity.● Skull:- Use a Vernier caliper.- Measure skull length between the back of the skulland the extremity of the nose (Fig. 36).- Be sure to position one extremity at the back of theskull and not above or below (eventually locate theback with fingers).Figure 34: Hind foot measurement not includingclaw (Photo: Herbreteau P.)Figure 35: Ear measurement (Photo: Herbreteau P.)Figure 36: Skull measurement (Photo: Herbreteau P.)21