Microchip Placement For Identification of Birds

Introduction

There are many ways to identify individual birds. Historically, the most common method has been to place a band around the tarsometatarsus. The band can be closed, if placed on a neonate, or open, if placed on a mature bird. Banding has the advantages of being simple and inexpensive. Once placed, however, bands may fall off or become difficult to read. Additionally, bands that are too small may constrict the leg and cause vascular injury to the foot, and bands that are too large may become caught on items in the enclosure, leading to soft tissue injury, fracture, or even death.

In the last 15 years, microchip implantation has become a popular method of permanent identification in dogs, cats, and laboratory animals. A battery-free transponder or microchip is inserted into the subcutaneous space or muscle tissue. When read by the appropriate scanner, the microchip provides an identification number that can be associated through a database with information about the animal and the owner.

Advantages & disadvantages

Microchip implantation provides permanent and unique identification.

The disadvantages of microchip placement include its relatively high cost, the technical challenge of placement and the difficulty of placement in birds weighing less than 100 g. There is also the potential for local tissue reactions to the microchip. Most reactions are transient, but transponder-associated sarcomas have been reported in dogs, rodents, and an Egyptian fruit bat.

Equipment

Two companies in the United States currently market microchipping systems: AVID (Avid Identification Systems Inc., Folsom, LA) and HomeAgain (Schering-Plough HomeAgain LLC, Kenilworth, NJ). Both systems include the transponder in a single-use syringe for initial implantation (Fig 1).

Figure 1. Shown here, a single-use syringe for transponder implantation and a microchip scanner. Photo credit: Dr. Elinor Granzow.

The following supplies are needed for implantation of a microchip into a bird: the microchip in its syringe, microchip scanner, alcohol, and tissue glue or suture material. Anesthesia and analgesia are used at the discretion of the clinician.

Procedure

During microchip implantation, the bird may be awake and well restrained or under general anesthesia. Some clinicians prefer to use general anesthesia, because the needle is large and could potentially cause tissue damage if the bird struggles during implantation.

1. Prior to microchip placement, thoroughly scan the bird to ensure a microchip is not already in place. Also scan the microchip prior to implantation to be sure the signal is recognized by the scanner and to confirm the identification number of the microchip.
2. Position the bird in dorsal recumbency. Expose the apterium or featherless tract lateral to the keel. Pluck birds without apteria, such as waterfowl. Briefly apply alcohol.
3. Place the microchip superficially in the left or right pectoral muscle region. Use the thickest portion of the pectoral muscles, which in most birds is in the upper one-third of the muscle mass approximately one-third of the width lateral to the keel. Hold the syringe containing the microchip with the bevel facing up at a 45-degree angle (Fig 2). Insert the needle into the muscle until the bevel is no longer visible. If the bird has sufficient muscle mass, pass the needle for several more millimeters. Completely depress the plunger and then withdraw the needle. It may not be possible to place a microchip in an extremely thin bird with substantial muscle wasting.
   

   Figure 2. The transponder is inject at an approximately 45 degrees angle to the left of the keel. Photo credit: Dr. Elinor Granzow.

4. Confirm microchip placement by scanning the bird. Depending on the scanner type used, hold the scanner 3 to 20 inches (4 to 50 cm) from the sternum.
5. Oppose the skin edges around the hole created by the needle using fingers or two cotton-tipped applicators and apply a drop of tissue glue (Fig 3). Alternatively, close the skin with sutures, especially if there is hemorrhage post-implantation. The latter method may bring the bird’s attention to the area and result in the bird picking at the sutures.
6. Pain medication is not routinely given to birds after microchip placement.

Figure 3. After microchip implantation, a small amount of tissue glue is applied to the skin edges. Photo credit: Dr. E. Granzow.

Complications

Complications are not commonly associated with microchip placement in birds. Potential complications include evidence of pain or irritation, hemorrhage, infection, or accidental subcutaneous placement of the chip.

• Accidental subcutaneous placement of the microchip can occur if the needle of the application syringe is not inserted deeply enough into the pectoral muscle. This may result in the microchip being palpable under the skin, potentially irritating the bird. I recommend removal of subcutaneous microchips and proper intramuscular placement of a new sterile microchip.
• Most birds return to normal activity shortly after microchip placement. Consider analgesia if the bird shows signs of discomfort such as fluffed, lethargic, decreased vocalizations, anorexia, or holding up the leg on the side of the injection site. Opiate pain medication like butorphano or buprenorphine or non-steroidal anti-inflammatory medication such as meloxicam or ketoprofen can be administered. Most birds will return to normal within a few days.
• Although substantial hemorrhage is fortunately rare, application of skin sutures provides sufficient hemostasis for most cases.
• Infection of microchip sites has not been reported and is probably an infrequent occurrence. Minimize risk by cleaning the implantation site with alcohol and taking care to use aseptic technique.
• There are anecdotal reports of birds pulling feathers or damaging tissue over the injection site. This seems to be a rare occurrence; more often, the presence of a microchip is incidental to feather destructive behavior. If this behavior did not exist prior to chip placement but is initiated immediately afterward, analgesic therapy for the bird is recommended prior to attempting chip removal.

References