Restraint
& Handling of Live Amphibians
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Amphibian
Research & Monitoring Initiative
National Wildlife Health Center
ACUC Tracking No. 2001-005
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STANDARD
OPERATING PROCEDURE
ARMI SOP No. 100
Revised, 16 February 2001
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I.
PURPOSE: |
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Provide guidelines
for humane handling of amphibians so that injury and distress to the amphibian
are minimized.
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II.
SCOPE: |
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These guidelines
apply to larvae and tadpoles, as well as adult frogs, toads, salamanders
and neotenes. Because of their anatomically different and very delicate
skin, tadpoles and larvae must be handled differently than post-metamorphic
amphibians.
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III.
EQUIPMENT & SUPPLIES: |
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A. Standard capture
equipment (seine nets, dip nets, minnow traps)
B. Clear plastic bags (half liter or full liter size)
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IV.
BACKGROUND: |
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There are three main
hazards associated with handling live amphibians: two to the amphibian
and one to the handler. To amphibians, the main dangers of being handled
are skin damage that could result in secondary skin infections, and bone
and muscle injuries caused by struggling when being held. For the handler,
the main danger comes from toxic skin secretions produced by some amphibians
(in the USA, this is mostly newts and the introduced giant/marine toad).
Tadpoles and larvae
have thin delicate skin that is very easily damaged by the slightest handling.
The skin of larvae lacks keratin and has fewer cell layers than adult
amphibian skin. Therefore, direct contact handling of tadpoles and larvae
is to be avoided; instead, these amphibian stages are examined through
clear flexible plastic bags containing water. Although the skin of adult
(post-metamorphic) amphibians has keratin and is less delicate than larval
skin, their skin is still much more delicate than the skin of reptiles,
birds and mammals. Rough handling of adult amphibians can easily result
in skin abrasions, small tears, punctures, erosions and ulcers; normally,
minor skin wounds heal quickly, but if contaminants, sewage or high levels
of microorganisms are present in the pond or other environment, then wound
infections are possible.
Frogs and Toads. All
amphibians can be expected to struggle following capture. For anurans,
there is a danger that vigorous kicking with the hindlimbs can cause joint
dislocations or a broken (fractured) back; broken backs are a well-documented
and major problem in another species that moves by hopping---rabbits.
Therefore, proper restraint of anurans, first and foremost involves inhibiting
their ability to kick.
Salamanders. For
salamanders, there are three major dangers associated with handling: 1)
loss (automizing) of the tail, 2) damage to the very delicate external
gills (in neotenes), and 3) back injury during whip-like thrashing movements.
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V.
METHODS OF PHYSICAL RESTRAINT: |
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A.
Anurans |
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Medium and large
size frogs and toads (those about 5 grams and larger) should be grasped
around the waist with the hindlimbs fully extended. The animal should
not be allowed to bend (flex) its hip and knee joints, since this would
allow it to kick.
B.
Caudates |
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Medium and large
size salamanders (those about 5 grams and larger) should be grasped
in the middle of the body between the forelimbs and hindlimbs. Larval
and neotenic salamanders should never be grasped around the head or
neck, because the gills can be easily damaged. Under no circumstances
should salamanders be grasped by the tail or picked up by the tail.
C.
Larvae |
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All larvae (including
tadpoles) should be handled with nets or scoops. For examinations, the
larvae should be placed in a clear plastic bag with a mild amount of
water. Alternatively, larvae may be sedated with an anesthetic and examined
in a dish or bowl of water. As much as possible, larvae should be examined
only while they are in water. Larvae should not be grasped with bare
hands.
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VI.
MISHAPS: |
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A.
Skin wounds |
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If an amphibian
suffers a skin wound during handling, it is recommended that the wound
be sprayed with the over-the-counter product, Bactine® (See the
SOP on Toe Clipping of Frogs and Toads, NWHC ACUC Protocol 2001-004).
All other topical antiseptics and disinfectants (sprays and ointments)
are CONTRAINDICATED in amphibians. If possible, the animal should then
be released on land rather than into water, since the antiseptic spray
would be quickly washed off in water.
B.
Broken back |
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If a frog or toads
suffers a broken back during capture or handling, it should be promptly
euthanized. It would be inhumane to release such a crippled animal.
An animal with a broken back will have serious damage to the spinal
cord and should show almost immediate paralysis of the hindlimbs and
tail. Recommended methods of humane euthanasia include (see NWHC ACUC
Protocol 1999-009, Methods of Euthanasia):
1.
Pithing
2.
Overdosing in anesthetic solutions of MS222 or benzocaine
3. Application of a benzocaine-based topical
ointment (as used by humans to relieve tooth-aches) to the top or the
head and dorsum of the body.
C.
Broken leg |
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If a major bone
of a limb is broken during capture or handling, the animal should be
euthanized or taken to a wildlife rehabilitation center or veterinarian
for treatment. A broken leg bone typically is recognized as an abnormal
bend in the leg where there is no joint; other signs of a broken leg
bone are protrusion of a bone fragment through the skin, inability of
the animal to move a limb or position a leg in its normal resting posture.
After treatment, amphibians with broken bones might be given to a zoo
or placed in a captive breeding program. Only if the injured amphibian
is kept isolated from all other fish, amphibians and reptiles (eg, in
a separate cage) during treatment, can it later be considered for release
at the point of capture. Injuries to digits (toes and fingers) generally
are not life-threatening; if the skin of the injured toe also is wounded,
then treatment with Bactine® prior to immediate release is acceptable.
If a toe bone is broken and protruding through the skin, the affected
toe may be amputated just proximal to the site of the fracture, the
stump should be sprayed with Bactine®, and the animal may be released.
D.
Automized tail |
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If a salamander
automizes (detaches) its tail during capture or handling, the stump
should be treated (sprayed) with Bactine®; the salamander can then
be promptly released.
E.
Crushing injuries to head & body |
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Amphibians that
have serious injuries to skin, muscles and bones should be promptly
euthanized. Crushing injuries that are limited to a limb or tail will
require treatment at a wildlife rehabilitation center or a veterinary
clinic; alternatively, the animal may be euthanized, but it would be
inhumane to release a seriously injured amphibian.
F.
Snout abrasions |
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Amphibians that
are held in glass or clear plastic containers may jump head-first into
the glass, or may rub their snout against the container in attempts
to burrow out. If amphibians are held for more than an hour in a clear
container (bottle, aquarium, etc), they should be examined for evidence
of skin injury at the tip of the snout and elsewhere around the head
prior to release. If abrasions are detected, they should be sprayed
with Bactine® prior to release.
G.
Toxic skin secretions |
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All amphibians have
glands in their skin that secrete a vast number of chemicals; some of
which are merely noxious and repellant-like, while others may cause
skin or eye irritation, and some may actually kill. The poison-dart
frogs of Central America are an example of a frog with toxic secretions
that can kill a human. Among the native amphibians of the United States,
the two amphibians of greatest concern are giant toads (also called
cane toads, marine toads, aga toads; Bufo marinus) and
western newts of the genus, Taricha.
Giant toads secrete
a potent white mucoid substance from their parotid glands (large warts
just behind the eyes) that affects the heart, but it is not absorbed
through the intact human skin; however, the toxin is readily absorbed
through the eyes and mouth. Hence, the best way to prevent poisoning
is to carefully avoid rubbing the eyes or putting fingers in the mouth
after handling a giant toad. If skin secretions of giant toads contact
the eye or mouth, then flush promptly with generous amounts of clean
fresh water or contact lens wetting solution, and then seek emergency
care at a clinic or hospital if stinging or numbness of the eye or mouth
develops.
Newts of the genus,
Taricha, also secrete toxins from their skin; it is presumed that the
entire body of these newts secretes toxins (newts and other salamanders
do not have parotid glands). Their skin secretions are very irritating
to the eyes and mouth. Temporary blindness (lasting about 24 hrs) has
been reported by field biologists that handled newts and then rubbed
their eyes. If sensations of blurred vision,or burning or stinging of
the eyes occur after handling any genus or species of newt, wash the
eyes with copious amounts of fresh clean water (or contact lens wetting
solutions) and promptly seek medical care. Persons with newt skin secretions
in their eyes are advised not to drive a vehicle or operate other dangerous
or heavy equipment.
Finally, it is possible
that other amphibian species in the USA besides giant toads and newts,
could produce skin secretions that are irritants to the eyes. Furthermore,
amphibians may carry some bacteria in their intestines and feces that
are human pathogens, such as the bacteria, Salmonella and Leptospira.
Hence, it is always best to practice good personal hygiene after handling
any amphibian (namely, thoroughly wash your hands with soap and water).
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VII.
CITED LITERATURE: |
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1. MARTIN,
D., and H. HONG. 1991. The use of Bactine® in the treatment of open
wounds and other lesions in captive anurans. Herpetol Rev 22: 21. |
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