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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).

Previously, the only method we had to isolate important frogs was keeping them in an individual tank, 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 and requiring a reader in order to determine the unique code. Visible implant elastomers and Visible Implant Alphanumeric Tags are a much cheaper solution although they can sometimes be more difficult to read. This table summarizes the strengths and disadvantages of microchips and alphanumeric tags.



Picture 1: Size of the microchip compared to a penny

Picture 2: Chip inserted in right rear leg

Picture 3: Chip reader inside protective cover

Picture 4: Chip reader


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 (Picture 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 hole left by the syringe was quite large, and the chips often fell out. We purchased chips in a non-sterile vial, and have been inserting the chip with surgical instruments. We disinfect the chips and insertion equipment, but the procedure is not sterile (See How to section below). We have had good success with this method so far, and have had no cases of infection.


We have successfully inserted the chips in the dorsal lymph sac but found the chip tended to migrate from this location. We now insert the chips in the rear leg. 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 use Alphanumeric Tags.


We have had some chips fall out. Possible causes include an overly large incision, or inadequate amounts of tissue glue. In these cases, we wait for the incision to heal and re-insert the chip. We are planning to try placing a suture to close the incision. This may reduce the incidence of chip loss.



We also use "Visible Impant 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 our important frogs.


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)


Materials for disinfecting microchip

Bleach, 10 ml.

70% isopropyl alcohol, 20 ml

15 – 20 ml polypropylene tube for soaking chip

Instruments (Picture 3)

            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 tag(we use

VetBond (3M) or other tissue glue (Picture 4)

1cc syringe with 30ga needle to apply glue (Picture 4)

Stack of paper towels



Picture 3: Instruments

Picture 4: Tissue glue and needle/syringe

for application



Record Microchip number

Record the microchip number in your database. Numbers are usually scanned by turning on the reader, pressing a “Read” key, and passing the device over the chip. You must be fairly close to the chip. We’ve had good success holding the frog in your hand and then reading the chip through your hand. 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 microchip

It is very important to disinfect the microchip as thoroughly as possible. We use Bleach and 70% ethyl alcohol. Two days before the procedure, immerse the chips in 10 ml bleach overnight. We find a 15- 20 ml polypropylene tube works well. The day before the procedure, remove the chip from the bleach, rinse with 70% ethyl alcohol, and immerse in 10 ml 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.


Disinfect instruments

Scrub instruments with disinfecting soap and rinse well. Soak instruments in ethyl alcohol for 5 minutes prior to each procedure.

Prepare tissue glue

Draw up a small amount (approximately 0.025 ml/frog) of tissue glue into the 1 ml syringe with a 30 ga needle. . (See Picture 4 above) We find the needle allows finer control over the placement of the glue. The tip of the glue bottle dispenses a rather large drop, and is prone to clogging.

Prepare work area

            Lay out 3-5 damp paper towels.

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

Everyone involved should wear gloves.

Restrain the frog

Have an assistant restrain the frog. There are a number of methods to accomplish this. The Burrito Method (Picture 6) or the Iron Claw are two methods which work well.

If the frog struggles, it may also help to have your assistant hold the rear leg to be used in an extended position.

We try to use the right leg routinely, for consistency. Use whichever leg is easiest to manipulate for you, and be consistent.

Picture 6: Have an assistant restrain the frog; avoid squeezing too tightly.



Inserting The Chip

Make the incision

Use forceps to hold up a “tent” of leg skin, ideally at the distal end of the femur on the dorsal surface just above the knee (Picture 7),or in the lower leg just below the knee. We find that in mature females the lower leg is just about the length of the microchip so that the chip fits snugly to where the skin tightly adheres at the knee and ankle. In that location, the chip seems to stay put relatively well and doesn’t migrate much. Try not to squeeze too hard, as this may damage the skin. A certain amount of pressure is necessary to grasp the skin.

Picture 7: Use forceps to grasp and lift a tent of skin.


Use scissors to make a very small opening, about 2 mm, in the skin just in front of the forceps. (We have tried this procedure with a scalpel blade and found it to be inferior. You may wish to experiment with this method.)

It is best to position the scissors close to the skin where you want to make the opening, and cut with a 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 - 3 mm to be ideal. Start with 2 mm, and enlarge if necessary. The larger the hole, the more likely it is the chip may fall out.


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. (Pictures 9,10) If the opening seems too small, it is worth making several more attempts with the chip held at different angles. Once you are convinced the hole is too small, enlarge the opening with the scissors. Make the additional cut as small as possible. Repeat the insertion attempt.

Picture 9: Grasp chip while holding skin up.

Picture 10: Gently slide chip into opening.


In some cases, we have found inserting the chip by hand works well (Picture 11). This is clearly not as clean, but allows much easier manipulation of the chip.


Picture 11: The chip can be inserted by hand.


Position the chip as far away from the opening as possible, to decrease the chances of it slipping out. (Picture 12) Use your fingers to gently push the chip where you want it. The ventral surface of the leg is good, as is the proximal portion of the thigh. Moving the chip can be difficult in male frogs, as their thighs are often not much longer than the chip. We have found Alphanumeric Tags work better for smaller frogs.

Picture 12: Position the chip away from the opening. Here the opening is visible at the distal end of the thigh, and the chip is above. It has been turned so the end is not facing the opening, decreasing the chances it will slide out.

Another location to insert the chip is in the lower leg. We find the chip moves less in this location. The insertion procedure is the same.


Close the Skin

Gently manipulate the edges of the opening so they are as close together as possible. Apply several drops of tissue glue directly to the opening. (Picture 13) We find it helpful to dab the skin dry, and apply enough glue to liberally cover the area. Allow the glue to dry for approximately 1 minute if possible. Try to hold the frog still until the glue is at least partially dry. The glue seems more likely to come off if it is submerged in water before it is dry.

Picture 13: Apply several drops of glue to the opening, and allow to dry.



Picture 14: Another view of the chip in place. The glue has dried to a white color.



Return Frog to Tank

We return the frogs to a tank in our flow thorough system following the procedure.


Monitor Frog

Check the frog daily to be sure the incision is healing and the chip has not fallen out. The area around the incision may turn white, which is scar tissue. Red or raw areas should lessen and disappear. While the incisions generally heal in 14 to 21 days, we keep the chipped frogs in the flow through system until we are sure the incisions are completely healed, about a month. The circulating water seems to result in better healing, compared to standing water changed daily.


Re-Check Chip Number

Once you are convinced the skin is healed, and the chip will remain in place, recheck the chip number against your database, to ensure numbers are accurately recorded for each frog. For us, this is about 3 weeks after the procedure. Again, the frogs should be kept in a flow thorough system for about a month, though they can be grouped together before this.


Following is a table comparing different aspects of the Microchip versus the Alphanumeric tag. Overall, the microchip is easier to read and has a lower rate of loss (for us), but it’s much higher cost is a serious consideration.



Alphanumeric Tag

Unit Cost: about $6/ chip

Unit Cost: about $1/tag

Addn’l Cost: chip reader (cost?), glue, instruments

Addn’l Cost: glue, instruments. Injector is $124, 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

Rate of Loss: Higher

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

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

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 (100+ years). In fact, the chip can be recovered from a dead frog, sterilized, and used again.

Lifetime: life of frog

Placement orientation: not a concern

Placement position: potential to be placed upside down or to curl/fold under the skin when inserting.




Contributed by Maura Lane