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Microchip Identification


We use Biomark 12 mm microchips (Biomark, Inc. 7615 West Riverside Drive Boise, Idaho 83714 Phone (208) 275-0011 Fax (208) 275-0031) to identify individual frogs in our colony. (Picture 1) There are a number of other companies which offer a microchip system, including AVID(, Home Again, and InfoPet (Trovan, 1.800.463-6738, 1-800-INFOPET).

We have also used "Visible Implant Elastomer Tags" and "Visible Implant Alphanumeric Tags" made by Northwest Marine Technology (P.O. Box 427, Ben Nevis Loop Road Shaw Island, WA 98286 tel (360) 468-3375 FAX (360) 468-3844 email Please check out the tagging section on the Harland Lab website for more information on these technologies.

Previous to tagging, the only method we had to identify important frogs was to keep them in individual tanks, or in a tank with one other frog of the opposite sex. There is ample opportunity for mixing up frogs in this situation. Microchips allow us to keep a number of important frogs together in one larger tank. We can keep more frogs in less space, and frogs are readily identified if they are mixed up. Microchips are somewhat expensive however, costing about $6 each. They also require a reader in order to determine the unique code. Visible Implant Elastomers and Visible Implant Alphanumeric Tags are less expensive solutions, although they can sometimes be more difficult to insert and read. This table summarizes the strengths and disadvantages of microchips and alphanumeric tags.

Picture 1: Biomark 12 mm microchip Picture 2: Chip inserted in right rear leg
Picture 3: Biomark Chip reader with protective cover

Picture 4: Chip reader

Microchip Alphanumeric tag
Unit cost: ~ $6/chip

Unit cost: ~ $1/ tag

Other costs: chip reader, glue, instruments, bead sterilizer Other costs: glue, instruments, bead sterilizer. Injector is ~ $125, but we don't use it

Code Identification: Simpler

Need a reader to ID. Little manipulation of the frog is necessary beyond simple restraint.

Code Identification: More Complex

Usually need brown glasses and blue light (both supplied) to fluoresce and read tag. Dark skin pigment interferes with reading code. Often requires manipulating frog to find/read the tag. Also may need to manipulate the tag under the skin to visualize the code.

Rate of Loss: Lower Tends not to fall out if it is placed on the side of the leg opposite the incision

If chip falls out, it can usually be recovered from the bottom of the tank

Rate of Loss: Higher

Tags tend to migrate under the skin and can be lost through an unhealed incision more easily.

If tag falls out, it is usually washed out of the tank, and cannot be recovered

Size: Larger

May not work in legs of smaller (male) frogs

Size: Smaller

Easily works with large or small frogs

Lifetime: life of frog.

The chip can be recovered from a dead frog, sterilized, and used again.

Lifetime: life of frog
Placement orientation: Should be placed away from incision site, ideally on the opposite side of the leg. Placement position: Placement can betricky. Potential to be placed upside down or to curl/fold under the skin during insertion.

All microchip systems basically work in the same way. The unique number carried by the transponder (microchip, Picture 1) is read by a chip reader (Pictures 3, 4) activated within a short distance of the chip. Reading distances vary by manufacturer. Check the Biomark website for more detailed information on the functioning of the transponder.

Each microchip company has a different reader for their system. Some readers will read only their brand of chips, others are "universal", and will read chips from many other companies. Be sure to check this if you need to read chips from different manufacturers.

Pre-sterilized chips are available preloaded in a syringe as a gas sterilized unit. We do not use this system. We had poor success using the syringe to insert the chip. The amount of force required to penetrate the skin after several uses was excessive. We instead purchase chips in a non-sterile vial, and insert the chip with surgical instruments. We disinfect the chips and use asceptic technique, but the procedure is not sterile (See the How To; section below).

We have successfully inserted the chips in the dorsal area, but found the chip tended to migrate from this location. We now insert the chips in the rear leg (Picture 2). Chips in the rear leg cannot migrate very far. Some male frogs are so small the chip will not fit in the leg, in which case we have used Alphanumeric Tags.

We have had some chips fall out. Possible causes include an overly large incision, inadequate amounts of tissue glue, or excessive amounts of glue. We find the latter to be a problem not only because the amount of glue irritates the frog, but the frog is able to hook a claw under the glue and pull it off, much like a scab. If the chip falls out, we wait for the incision to heal, and re-insert the chip.

How To Insert Microchips in X. tropicalis


12 mm Microchips- (Biomark, Inc. 7615 West Riverside Drive Boise, Idaho 83714 Phone (208) 275-0011 Fax (208) 275-0031)

1X benzocaine solution 45 ml in 50 ml Falcon Tube

Good light source and a table of appropriate height to avoid having to bend over while working. We find a table that allows one person to stand on each side is ideal for manipulation of the frog and instruments.

Materials for disinfecting microchip

70% isopropyl alcohol, 20 ml in 15 - 50 ml Falcon tube, for soaking chips

Bead sterilizer, for sterilizing instrument tips between procedures

Instruments (Picture 5)

Sharp, small scissors to make incision

  • We use spring scissors with a 3 mm cutting edge, but any type of small sharp surgical scissors will do


  • tissue forceps with teeth to grasp skin(we use Adson Brown, 1X2 teeth)
  • forceps with smooth, small tips to place chip

VetBond (3M) or other tissue glue (Picture 6)

25 - 30ga needles to apply glue from bottle(Picture 6)

Stack of paper towels


Picture 5: instruments for grasping and making incision in skin Picture 6: glue bottle with needle for applying glue


Disinfect microchip

It is very important to disinfect the microchip as thoroughly as possible. We immerse in 70% ethyl alcohol overnight. Remove the chip from the alcohol and allow it to air dry on sterile gauze approximately 5 minutes prior to the procedure.

Record Microchip number

Record the microchip number in your database. Numbers are usually scanned by turning on the reader, and pressing a "Read" key while holding the reader near the chip. You must be fairly close to the chip. (Once the chip is placed, we've had good success holding the frog in the hand and reading the chip.) A beep usually indicates the chip has been sensed, and the ID code is displayed on the reader screen. If no chip is sensed, try repositioning the reader, or getting closer. Try not to get the reader wet. We have found reading a chip near large metal objects, such as metal tables, does not work well. The metal seems to interfere with the reader's ability to function.

Disinfect/Sterilize instruments

Scrub instruments with disinfecting soap and rinse well. Immerse instruments in ethyl alcohol for 5 minutes prior to each tagging session. Between individual frogs, place tips of instruments in bead sterilizer for 5 seconds to sterilize the tips. Allow instruments to air cool for 10 - 15 seconds before use.


  • Allow bead sterilizer to come to proper temperature by turning it on about 10 minutes before use.
  • Do not immerse entire instrument in sterilizer, or immerse for longer than 10 - 15 seconds, as instruments can be damaged.
  • Use caution - beads are extremely hot and will burn you.

Prepare tissue glue

Open glue cap, snip off solid plug at end of dispenser if necessary, and place the 25 - 30 ga needle on the tip. (See Picture 6 above) We find the needle allows finer control over the placement and amount of glue. The open tip of the glue bottle dispenses a rather large drop, and is prone to clogging.

  • Notes: Use caution when working with the needles. It is good practice to discard the needle in a sharps container between each frog. This avoids having an exposed needle in the work area while preparing for the next implantation. Otherwise, you may want to recap the needle between frogs. Place the hub on the table, pick up the bottle and slip the needle into the hub. Do not place the hub over the needle.

Prepare work area

Lay out 3 - 5 fairly damp paper towels.

Arrange the instruments, microchip and sterile gauze within easy reach, and position your light.

Everyone involved should wear gloves.

Numb the frog's leg by suspending it in 1X Benzocaine solution for 30 sec - 1 minute, then allow about 1 - 2 minutes before starting procedure. A toe pinch test can help determine if the leg is numb. Re-immerse the leg if there is still a reflex.

Restrain the frog

Have an assistant restrain the frog. There are a number of methods to accomplish this. We prefer to first position the frog in dorsal recumbency(on it's back) on the wet towels using gentle manual pressure with a flat palm(this requires some deterity and practice). A paper towel can then be carefully manipulated under the hand to keep the frog moist. The frog will calm down after a short period in this position.

We insert the chip in the right leg for consistency. Position the frog's body to allow the best access for the person doing the chipping. Use whichever leg is easiest to manipulate for you, and be consistent.


Picture 7: Frog restrained in dorsal recumbency. Avoid pressing or squeezing too tightly.

Insert The Chip

Make the incision

Just prior to beginning, dip the forceps and scissors in the bead sterilizer for 5 - 10 seconds, and allow to air cool. Use forceps to hold up a "tent" of leg skin, ideally at the cranial end of the lower leg, on the ventral surface (Picture 8). Try not to squeeze the forceps too hard, as this may damage the skin. A certain amount of pressure is necessary to grasp the skin. Drying the skin and the forceps may help, but be sure to moisten the skin again soon.

  • In mature females there is generally plenty of room for the chip to fit in this location without stretching the skin. The chip seems to stay put relatively well and doesn't migrate. We have found Alphanumeric Tags work better for smaller frogs. If the chip is tight, consider removing it and using another method of identification.

Use scissors to make a small opening, about 2 mm, in the skin just cranial to the forceps. (We have tried this procedure with a scalpel blade and found it to be inferior.) It is best to position the scissors close to the skin where you want to make the opening, and cut with a single firm stroke. Gentle, timid cuts will cause the scissors to slide off of the slippery skin, resulting in small nicks rather than one clean opening. We find a cut of 2 - 2.5 mm to be ideal. It is preferable to make a slightly larger hole the chip will easily fit in, rather than forcing the chip through a small opening and causing skin trauma.

  • If it is a clean incision, and the glue is evenly applied to flat, well opposed tissue edges, the incision is more likely to heal with no problem.

Insert the Chip

Continue to hold the skin up with the forceps. Grasp the microchip with another pair of forceps, and slide it gently into the opening. If the opening seems too small, you can gently attempt different angles. If the hole is too small, enlarge the opening with the scissors. Repeat the insertion attempt.


Picture 9: Inserting Chip by hand

We have found inserting the chip by hand with a clean glove also works well (Picture 9). This is clearly not as clean, but allows much easier manipulation of the chip. The chip should slip in easily.

After the chip is inserted, wet your fingers with clean 1/9X MR and gently work the chip around to the dorsal surface of the leg (Picture 10). This reduces the chances the chip will fall out if the incision opens up. Moving the chip can be difficult in male frogs, as their legs are generally smaller than the female. We have found Alphanumeric Tags work better for smaller frogs. If the chip does not seem to move easily under the skin, consider removing it and using another method of identification.

Picture 10: Chip visible on dorsal surface, away from the incision.

Close the Skin

Gently manipulate the edges of the incision so they are closely opposed and flat. Carefully dab the skin dry. Apply a small amount of tissue glue directly to the opening. (Picture 11) We find one drop from a 25 ga needle works well. Apply the glue directly to the opening, and avoid getting glue on other parts of the frog. The technique we use:

  • Have a drop of glue just visible at the end of the needle, then touch the needle to one end of the incision. Use the tip of the needle to carefully guide the glue along the incision. This should result in a thin even film of glue, which dries quickly. Ensuring the glue is dry before returning the frog to water will reduce the chances of the glue coming loose.
  • Allow the glue to dry for approximately 1 minute if possible. A second thin application of glue may help create a good seal. In any case, avoid a large amount of glue. This will irritate the frog, and will be more easily rubbed away. Avoid getting the glue in the crease of the leg joint, which is particularly irritating to the frog.


After the chip is implanted, keep the frogs isolated in a quiet area in a tank of 1/9 X MR. Keep the water shallow, so the frog can sit on the bottom of the tank with the nose out of the water. We find reducing any external stimulation or need for movement to stay afloat reduces the chances the frog with rub at the incision.

  • The frog may rub at the implant site immediately after the procedure, but this should stop within a few minutes. Continued rubbing may indicate excessive glue, or a chip that is uncomfortable or too large.

We change the 1/9X MR daily, checking each frog carefully at this time. The frogs are returned to the system after 5 days, as long as the implant site appears to be healing normally. We check the area every other day for another week.

Updated by Sarah Kirschner and Maura Lane, 02/2011.