The overall goal of the following video is to familiarize the viewer with various techniques used for manual restraint and compound administration in mice and rats. Mice and rats can be restrained by a number of one or two handed techniques or with the use of plastic restrainers techniques for compound administration, such as intraperitoneal, subcutaneous, intravascular, and intradermal. Injection methods are demonstrated in this video as well as oral gavage and intranasal administration.
Learning how to handle animals confidently, gently, and safely is an important part of in vivo research. Animals should always be handled in a manner that's safe for both the animal and the researcher. Generally, people new to these methods may struggle as it takes time to become comfortable working with rodents.
Rodents may also intimidate or frighten people that are new to working with them. Visual demonstration of dose administration and restraint techniques is key to both successful administration of the compound as well as to prevent distress or injury to the animal and the restrainer. Mice can be restrained manually using either a one or two handed technique.
The first step of either method is to gently lift the mouse by the base of the tail onto the cage lid wire bar cage top, or a similar rough surface. For the one-handed technique, tuck the base of the tail between the third and fourth finger while gently pulling back on the tail. This will cause the mouse to grasp the surface and pull forward.
Next firmly. Grasp the mouse by the scruff with the same hand that is holding the tail. Grasp with the index finger and thumb near the base of the head and extend the grasp down the back by incorporating the middle and ring fingers.
Be sure to apply just enough pressure to the skin around the neck to prevent the mouse from turning or twisting, but not so much that the animal cannot breathe. The two-handed technique is similar except that while one hand gently pulls back the tail, the other hand quickly and firmly grasps the mouse by the scruff of the neck with the tail in one hand and the scruff in the other. Lift the mouse and tuck the base of the tail between the palm and the third or fourth finger of the hand holding the scruff.
As before, be sure the grip is secure, but still allows the animal to breathe. Rat scruff is generally performed two-handed. First, remove the rat from its cage and place it onto a rough surface.
Next, grasp the rat by the tail with the non-dominant hand and pull. Gently backwards, hold the tail firmly in one hand and approach the scruff of the rat from the rear with the other. Apply gentle pressure to the back of the rat while moving up to the shoulder blades.
And finally, grasping the scruff between the fingers and the palm of the hand. Rats may vocalize when restrained in this fashion. When using an over the shoulder grip, grasp the rat by the tail with the dominant hand and pull gently backwards.
Next, place the non-dominant hand over the rat's back approaching from the rear. Grasp the rat around the thorax with the ring finger, pinky and thumb. The rat's head should be between the index and middle fingers.
Another method of restraint is the under the shoulders grip. Grasp the tail with the dominant hand as seen before and place the non-dominant hand over the rat's back approaching from the rear. Next, grasp the rat around the thorax right under the shoulder blades.
The rat's forearms should be gently pushed up with the thumb and index finger. The forearms should cross under the rat's chin, preventing it from biting. The rat can be held in this manner with one hand if the body is stabilized against the handler.
A flexible cone-shaped piece of thin plastic called a de capic cone can also be used for restraint to use. Push the animal forward until its nose protrudes from the hole in the end of the dec Capone either hold the bag closed around the tail or use a rubber band or twist tie to secure the animal in place. Once restrained injections can be administered through the plastic material, a rigid plastic container is useful when access to the tail is needed.
Insert the rat as described by the manufacturer of the device. With this type of restrainer, the rat is gently pulled backwards into the restraint by the tail. Place the closure on the front of the device and adjust it to limit the movements of the animal.
If animals appear to be agitated, towel restraint can be used when placed over the animal, the darkness and gentle restraint provided by the towel, can calm a fractious rat. Place the towel gently over the rat and then grasp the rat carefully around the body. Wrap the towel around the rat, being sure not to the rat's nose.
Move the towel so that the part of the body for injection is exposed. Before performing any of the following administration techniques, it is beneficial to practice handling the syringe. Ideally, one hand will manipulate the syringe while the other restrains the animal needles are best inserted into the animal with the bevel up, especially for intravenous injections.
Fine gauge needles are easily damaged with insertion into vial stoppers. Use a larger gauge to withdraw materials and then replace with a smaller gauge for injection. Intranasal administration is used for some types of infectious agents in allergy and asthma work, and in some studies involving the lungs.
Intranasal administration does not require anesthesia and surgery as intra tracheal installation. Would for intranasal administration restrain the animal as described earlier, using a syringe or pipetter place a small amount of the material to be inhaled at the nares of the animal. Watch for the material to disappear into the nares and repeat as necessary.
Compounds are administered intramuscularly if they require rapid uptake and can be administered in very small volumes. Restraint for intramuscular injections may take two people since one hind leg must be free and stabilized for injection. Insert the needle perpendicular to the skin over the animal's quadriceps or lateral thigh muscle mass.
Be careful not to inject into the posterior muscle mass as it is possible to damage the sciatic nerve. Intraperitoneal administration is chosen if there is a large volume of compound to be administered, and it is acceptable for the absorption rate. To approximate that of oral administration.
To perform an intraperitoneal injection, restrain the animal and point the tip of their nose toward the floor. To expose the abdomen, locate the animal's midline and mentally. Divide the abdomen into quadrants.
Choose an injection site in the lower quadrants, especially in the animal's. Lower right quadrant, use an appropriately sized syringe and needle to inject the material into the animal. Subcutaneous administration of a substance is used when slow absorption is desired.
Mice and rats have large amounts of loose skin, so relatively larger volumes can be subcutaneously when compared to humans. For subcutaneous injections, loosely restrain the animal as previously shown. Grasp the skin and gently pull it upwards.
Making a tent using an appropriately sized syringe and needle, insert the needle at a 30 to 45 degree angle into the tented skin and inject the material. A small swelling under the skin is the mark of a successful injection. If animals are to be handled routinely after subcutaneous injection, do not use the scruff.
Instead, use the skin on the dorsal rump. If animals are to receive multiple subcutaneous injections, alternate sites of injection restraint for animals during intradermal administration may be difficult and require the use of chemical sedation. If an anesthetic is used, be sure that it does not interfere with any research goals.
When performing an intradermal injection, first, remove hair from the injection site so that the skin is clearly visible at the site of injection. Insert an appropriately sized needle into the skin at a 15 to 30 degree angle. Do not insert the needle very far.
If inserted correctly, the injection should meet with resistance. A small bleb, which is pale than the surrounding skin will be visible if the injection was successful. Apply gentle pressure to prevent backflow of the material.
Intravascular administration is used for a wide variety of compounds and is the best root when the compound can be appropriately formulated and a very quick effect is desired For an intravascular injection into the lateral tail vein, restrain the animal in a decap cone or plastic rodent restrainer. As demonstrated previously, hold the animal's tail by the tip with the non-dominant hand to straighten and rotate. One quarter turn to place the tail veins dorsally.
Identify one of the two lateral tail veins for injecting while avoiding the ventral tail artery. Approach the distal portion of the tail with the needle at a 15 to 20 degree angle and inject the material. A successful injection will result in the material entering the vein with no resistance and blanching of the tail vein for the duration of the injection.
Placing the injection more distally preserves an undamaged portion of the vein that can be used if the first attempt is unsuccessful. Intragastric administration or oral gavage is only performed on restrained awake animals as anesthesia or sedation increases the risk of aspiration compounds being safety tested for human oral administration are often administered in this fashion. Begin by selecting an appropriately sized oral feeding needle.
The length is determined by holding the restrained animal up and measuring from the corner of the mouth. The ball tip of the feeding needle should reach to the animal's. Last rib, restrain the animal so that its head and body are in a straight vertical line.
This straightens the esophagus, allowing for easier passage of the feeding needle. Insert the ball tip of the needle into the animal's mouth over the tongue. Once the needle is in place, bring the needle and syringe up pressing gently against the palate so the animal's nose is toward the ceiling.
The needle may need to be redirected slightly as it passes the back of the throat. Any tension on the needle indicates the need to adjust position continue to pass the needle until the predetermined distance is reached. The needle should pass easily and the animal should not gasp or choke administer the substance.
If there is resistance or the animal gasps, chokes, or turns blue immediately stop and remove the needle. Once mastered, these techniques will allow you to safely administer doses to both rats and mice and effectively restrain them. While attempting these procedures, it's important to remember that a correctly restrained animal makes the procedure safe for both the animal and the handler.
Don't forget that working with animals in science is a privilege and responsibility. Choosing the correct restraint method and appropriate routes of administration is both good science and good welfare.
