VIII Records and
Information Control
A. IDENTIFICATION OF INDIVIDUALS
1. Numbering
The identification of individual animals-often necessary for the
management of experimental animals-is mandatory in breeding and
genetic procedures. Several techniques can be used to identify
individual amphibians. Selection depends on the species and the
developmental stage. Ideally, the system of choice would allow
identification of individual animals at all stages of development
from the time of fertilization through larval and postmetamorphic
development. However, aside from isolation in individual enclosures,
no system adequate to accomplish this objective is available.
In practice, a clutch of eggs or a shipment of animals may be
given a serial identification number such as 35,000 with subsequent
numbers in the series reserved in proportion to the number of
clutch or shipment members to which individual numbers will be
assigned. As animals are assigned for specific experimental purposes,
the experimental group or individual may be given numbers from
among those reserved. Thus, 35,XXX identifies the clutch or shipment;
the hundred's digit may be used to identify groups and the ten's
and unit's digits to identify individuals. Serial numbers that
do not include letters are recommended to facilitate adaptation
to computer techniques, should these be found useful (see Section
B below). Identification numbers may be written in waterproof
ink on waterproof labels that, when appropriate, may be easily
transferred from one enclosure to another. In the Amphibian Facility
of the University of Michigan, it has been found useful to assign
unique group numbers to members of a clutch or shipment that share
an enclosure. This permits
tracing enclosure mates and identifying individuals with common environmental experiences.
2. Tattooing
Tattooing by ink injection techniques has proved successful. It is particularly useful for larvae with well-developed tail fins, although its use is not limited to them. In this technique the animal is lightly anesthesized (see Chapter IX, Section F) and a fine needle attached to a hypodermic syringe containing tattoo ink is inserted into the tail fin or into the skin. The ink is injected as the needle is withdrawn, leaving a "bar" of ink. By using inks of several colors and forming a series of parallel bars, unique identification codes may be constructed. Recently, several useful variations on this principle have been published (Woolley, 1973).
Tattooing by the use of vibrating needles, as used in human tattooing, cannot be applied to larvae or small postmetamorphic animals; in fact, this method can only be used for larger postmetamorphic animals and even then must be renewed frequently. R. pipiens and bullfrogs retain such a tattoo for only 3-4 months. Because these and other amphibians shed their skin, it is difficult to assure that the needle-driven tattoo penetrates into skin layers that are not lost.
3. Branding
Wolf and Hedrick (1971) describe "chemical branding" as a procedure for marking Xenopus; these are permanent for at least a year. Using a cotton swab dipped in a solution of 0.5 percent amido Schwartz in 7 percent acetic acid, label figures are formed on the back of an animal after mucous secretions are removed by repeated wiping with paper tissues. After 1 min of contact the animals are returned to an enclosure. The dye provides a temporary identification until scar tissue is formed a few days later in response to the acid treatment.
The cold branding technique (Farrell and Johnson, 1973) has proved satisfactory for adult R. pipiens and R. catesbeiana and may be applied to the dorsal surface where the label can be easily read. The advantage of this technique over tattooing is the longer period of label retention. However, cold branding also disappears with time and cannot be applied to juvenile animals. Tattooing and cold branding are preferable to heat branding because they result in less trauma to the subject.
Urodeles can be tattooed or branded at relatively early stages
if it is done under light anesthesia (see Chapter IX, Section
F). Such markings are lost, however, as the skin is shed and must
be renewed periodically.
4. Toe Clipping
Toe clipping is an effective technique for amphibian identification and is appropriate for most anurans that do not readily regenerate lost digits. However, it is inadequate for urodeles and Xenopus in which the regeneration process replaces the removed digits, unless the regeneration is inhibited by treatment with berilium nitrate (Heatwole, 1961).
Ranidae may be toe clipped shortly after metamorphosis using light anesthesia and cuticle scissors. Although older R. pipiens may be toe clipped with scissors, mature R. catesbeiana, because of their size, may bleed excessively and danger of local infection occurs when toes are clipped in this manner. However, toe clipping large anurans may be accomplished by using an appropriate cautery knife or loop to seal the wound at the time of amputation. A coding system for toe clipping based on the system for punching edge coded cards and that allows 9,999 individuals to be distinguished with only two amputations per foot is illustrated in Figure 24.
5. Other Marking Systems
Various systems for labeling amphibians by the insertion of plastic
rings and other devices have been attempted but without notable
success.
6. Drawings and Photographs
The most foolproof method of identifying individual amphibians is the use of photographs that record the details of natural disruptive patterning. Figures 25, 26, and 27 illustrate disruptive patterning in R. pipiens and how these patterns are coded for identification purposes in the Amphibian Facility of the University of Michigan (Nace et al, 1973). Similar classification of the patterns of other amphibians is possible, but has not as yet been completed.
In laboratories with small numbers of animals, it is adequate to prepare duplicated outline drawings of the amphibian and to fill in these outlines with drawings of the disruptive patterning. This technique, however, is too time-consuming for a large colony of animals; thus, photographs are recommended. Using the classification system, it is possible to identify quickly the class of patterns to which an animal belongs and then, by comparison with the appropriate specific photographs or drawings, to identify the individual animal. When the pattern classification and recorded pattern are used in conjunction with other characteristics-such as sex, last recorded snout-vent length, and other unique characteristics-a very large number of individuals may be identified.
B. INFORMATION CONTROL SYSTEMS
The management of animal colonies or of data collected in even small colonies becomes increasingly complex as the numbers of animals or the history of the colony increases. This problem can be greatly alleviated by the adoption of computer-based techniques. Recent improvements in available computer programs and time-sharing techniques, even over long-distance telephonic connections, permit even those inexperienced in computer use to adopt these procedures readily. Although they may be adopted at anytime in the history of a colony, the earlier they are used, the greater the economy that is realized. Current technology is sufficiently advanced that standardization of the data base or of the software is not necessary. It is sufficient to record the available data in machine-readable form; the computer itself can restructure the data in accordance with the requirements of specific current or future software.
A computer-based system currently in use for the management of amphibians is described in some detail in Nace et al (1973). This system is in the public domain and accessible to long-distance users. Other systems that may be adaptable to users of amphibians include the LRE system (Laboratory Research Enterprise, Inc., Kalamazoo, Mich.) for Beagles and a system used for microorganisms (Bachmann et al., 1973).
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