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Micro RFID Tags for Lab Animals and Rodents: How to Choose

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Try marking 200 mice by ear punch or toe clip and keeping every record straight. Now try it for a study that runs six months. Marks fade, cage cards get swapped, and one mix-up can spoil weeks of data.

A micro RFID tag fixes that. A tiny chip under the skin gives each animal its own number for life. A reader picks it up in under a second, and you never have to handle the animal roughly to identify it.

This guide covers the tag types, LF versus UHF, sizes for mice and rats, and the questions labs ask us most.

What a micro RFID tag?

A micro RFID tag is a chip, a coil antenna, and a sealed casing, all very small. The chip stores one number. That number belongs to one animal.

The tag has no battery. When you hold a reader near it, the reader’s signal powers the chip, and the chip sends back its number. Since nothing runs down, the tag works for the animal’s whole life.

The tag types, and which animals suit each

Glass tags are the standard for rodents. A glass tag is a small capsule, roughly the size of a grain of rice or smaller, that you inject under the skin. Common sizes run from about 1.4 × 8 mm for mice to about 2.12 × 12 mm for rats.  The glass is biocompatible, and the tag stays put once the tissue closes around it.

Implants is the broader term. In practice, most rodent implants are glass tags. Some come in a sterile, pre-loaded applicator, which saves prep time and lowers infection risk. 

Ear tags work well for larger animals such as rabbits, guinea pigs and livestock. For mice, they rarely make sense, because a mouse’s ear is too small and too thin to carry one. Rats, hamsters and gerbils fall in between, and most labs still choose an implant for them.

If you work with mice or rats, plan on a glass tag. RFID Ear tags are worth considering only when the animal is big enough to carry one comfortably.

Read More: RFID Animal Ear Tags & Product Tags Guide

LF or UHF for small animals

LF, at 134.2 kHz, is what nearly every lab uses. It follows the ISO 11784/11785 standard (FDX-B), so tags and readers from different makers usually work together. LF handles the water and tissue in a small body well, and the short read range is a plus here. You can tell which animal you scanned, because the RFID sheep tag reader​ only sees the tag right next to it. 

UHF, at 860 to 960 MHz, reads from farther away and can scan many tags at once. That sounds appealing, but it works against you in a rodent room. Small UHF tags have a tiny antenna, so their range shrinks a lot. Body tissue also absorbs UHF signals. And if you scan a rack of cages, you may pick up several animals when you wanted one.

Our advice: choose LF for lab animals. Look at UHF only if you have a special setup, such as reading tags in a tunnel or arena, and test it first. 

How to match size to species

Tag size matters more than most buyers expect. A tag that is too big can bother a small animal, and a tag that is too small may give you a weaker read.

1. Mice: Pick the smallest glass tag your reader supports. Most labs wait until the mouse is old enough and heavy enough for the implant. Follow your institution’s protocol and your vet’s advice on minimum age and weight.
2. Rats: A slightly larger glass tag is fine, and its bigger antenna gives a stronger read.
3. Other small animals: Check the manufacturer’s size guide for hamsters, gerbils and similar species.

Before you order a big batch, test one tag with your actual reader. Micro tags and cheap readers don’t always get along.

How implanting works

Your protocol comes first, and your institution’s animal care committee has the final say. In general, the steps look like this:

1.  Restrain the animal gently, or use light anesthesia if your protocol calls for it.
2. Clean the injection site.
3. Inject the tag under the skin with a sterile applicator, usually between the shoulder blades.
4. Press the entry point closed if needed.
5. Scan the animal right away to confirm the tag reads.

Always scan once after implanting. It takes two seconds, and it tells you the tag works before the animal goes back to its cage.

Things to check before you buy

1. Reader support. Confirm your reader reads FDX-B tags at this size.
2. Sterility. Decide whether you want pre-sterilized applicators or plan to sterilize yourself.
3. Imaging. Glass tags can create artifacts in MRI scans. If you image your animals, ask about this first.
4. Batch tracking. Make sure you receive the list of tag numbers with each order.
5. Data format. Check that the number format matches your colony software.

Need help choosing?
Tell us your species, your reader and your batch size, and we’ll suggest a tag. You can also browse our RFID animal tags.

FAQ

What is a micro RFID tag for lab animals?
It is a very small passive RFID tag, usually a glass capsule, that is implanted under the skin. It gives each animal a unique number that a reader can scan.

What is the best RFID tag for mice?
Most labs use a small FDX-B glass tag at 134.2 kHz. Pick the smallest size your reader supports.

Can rats and mice use the same tag?
Rats can carry a larger tag, which reads more easily. Mice need the smaller size.

Are RFID implants safe for rodents?
Glass tags are made from biocompatible material and are widely used in research. Good technique and sterile applicators keep risk low. 

How long does a rodent RFID tag last?
It can last the animal’s whole life. The tag has no battery and no moving parts.

Can I use UHF tags on small animals?
You can, but the read range is short, and body tissue weakens the signal. LF is more reliable for rodents.

Do RFID tags affect an animal’s behavior or health?
Studies and lab experience show glass tags are generally well tolerated. Check current literature and your own approvals for your species and study type.

How do I read a tag under the skin?
Hold a handheld or plate reader close to the animal. The reader shows the tag number in under a second.