WILDLIFE CHEMICAL
IMMOBILIZATION1
Terry J. Kreeger
Supervisor, Veterinary Services Branch
Wyoming Game and Fish Department
2362 Highway 34
Wheatland, WY 82201
1Presentation
prepared by N. J. Silvy
Introduction
Chemical immobilization is the use of drugs to capture or restrain
animals. The term “immobilization” describes the actions of such
drugs which can range from tranquilization to paralysis to general
anesthesia.
Considerations-Questions
► What
is the species, age, sex, and physical condition
of the animals being captured?
► What need to be done with or to the animals while
they are restrained?
► Is physical restraint or chemical immobilization the
better option?
► Is adequate assistance available?
► Is the proper equipment available?
► What is the local geography and landcover like?
► What is the local weather on the capture days?
Characteristics of Ideal
Immobilizing Drug
► Wide
safety margin for a given dosage
► Compatible with other drugs and solutions
► No adverse tissue reaction if administered
intramuscularly
► Short induction time
► Should be reversible (with an antagonist or antidote)
► Chemically stable
► Concentrated to allow small volume dosage (~2–3ml)
► Low cost
► Not a controlled substance
Legal Considerations
►
Conditions for the use of drugs (pharmaceuticals) are
established by the Food and Drug Administration (FDA). Only
4 drugs have been specifically approved by the FDA for use on
certain wild animals: carfentanil for use on cervids; xylazine
for use on elk and fallow, mule, sika, and white-tailed deer;
yohimbine for use on cervids (deer and elk); and ketamine for
use on primates.
►
However, the Animal Medicinal Drug Use Clarification Act of
1994 essentially allowed approved animal and human drugs to
be used “extra label” under certain conditions. In general, those
conditions are the drug: (1) approved by the FDA; (2) used by,
or on the lawful written or oral order of, a licensed veterinarian;
and (3) used within the context of a valid
veterinarian/client/patient relationship.
Additional Legal Considerations
► Additionally, if
the animal could be consumed
by a human, the veterinarian should: (1)
establish a substantially extended withdrawal
time (the time from the date that a drug was
administered to when the animal can safely be
consumed by humans); (2) be able to identify
the treated animals; and (3) assure that
assigned timeframes for withdrawal are met
and no illegal residues occur.
Controlled Substances
A controlled substance means a drug that is identified in 1 of 5
schedules established by the Drug Enforcement Administration
(DEA). Special regulations govern the recording and storage of
these drugs. Act requires an individual to have a special DEA
registration number in order to possess controlled substances.
Biologists have obtained a DEA registration number and have
been able to procure drugs through veterinary product distributors.
However, even though they are in possession of these drugs, they
cannot use them on animals without veterinary supervision. Nonveterinarians can legally administer drugs if a valid
veterinarian/client/patient relationship is established. The
veterinarian does not have to be on site during the actual
immobilization event, but he or she should be involved in the
planning process.
Drug Schedules
Schedule I: This is reserved for experimental and abused drugs
such as heroin, marijuana, and lysergic acid diethylamide (LSD).
No capture drugs are Schedule I.
Schedule II (IIN): This includes most of the opioids used for
animal immobilization, such as etorphine, fentanyl, sufentanil,
and carfentanil and the opioid antagonist, diprenorphine.
Schedule III (IIIN): This contains ketamine and
tiletamine/zolazepam.
Schedule IV: Includes benzodiazepine tranquilizers, such as
diazepam and midazolam, and butorphanol.
Schedule V: This covers small, limited quantities of narcotic
drugs included in preparations with non-narcotic active medicinal
ingredients. No capture drugs are Schedule V.
Types of Drugs Used:
Tranquilizers
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Usually will not cause immobilization by themselves
Increase effectiveness of other agents
Nearly always used in combination with other agents
Examples
►Phenothiazine derivatives (readily available )
 Promazine (Sparine®)
 Acetylpromazine (PromAce®)
 Chlorpromazine (Thorazine®)
►Droperidol (Innovar-vet® )
►Haloperidol
Types of Drugs Used: Sedatives
 Can induce immobilization by themselves (depending on
species)
 Can be used in combination with other agents
 Produces hypnotic-like state
 Manipulation of sedated animal may produce arousal
 Examples
►Diazepam (Valium®)
►Xylazine (Rompun®)
 Wide safety margin but may not effect
immobilization
 Reversible with yohimbine (Antagonil®)
 Readily available
Types of Drugs Used:
Neuromuscular Paralytic Agents






►
Narrow safety margin
Under dosage produces no effect
Over dosage produces apnea (stops breathing)
Not reversible
Fairly readily available
Examples
►Nicotine sulfate (extraordinarily narrow margin of
safety)
►Succinylcholine chloride (Sucostrin®, Anectine®)
Types of Drugs Used: Dissociative
Anesthetics
 Ketamine hydrochloride (Ketaset®, Vetalar®)
► Wide margin of safety
► Used with a wide variety of animals
► Often used with xylazine or
acetylpromazine
► Produces catatonia-like immobilization
► Reversible with tolazoline (Priscoline®)
► Readily available
► May need large volumes for some species
 Tiletamine and zolazepam (Telazol®)
► Zolazepam is a tranquilizer, so no others
needed
► Wide margin of safety
► Used with a wide variety of animals
► Federal permit required; Schedule III
controlled substance; must be under the
authority of licensed veterinarian
 Phencyclidine hydrochloride
(Sernylan®)
► Wide margin of safety
► Was the agent of choice for large
carnivores (e.g., Ursus spp.)
► Can be combined with
tranquilizers
► Not readily available; Schedule
II controlled substance; must be
under the authority of licensed
veterinarian
► Compound also known as PCP
or "angel-dust"
► Human abuse potential
Types of Drugs Used: Narcotic
Anesthetics
 Not readily available, controlled substances
 Significant risk to humans
 Used on a wide variety of animals, especially
ungulates
 Can be used with other agents
 Reversible with naloxone (Naline®) or specific
antagonists
 Examples
► Etorphine (M-99®)
 Readily reversible with diprenorphine (M50/50®)
 May require larger volumes in megaherbivores
 Often used with xylazine
 Available with acepromazine as Large and
Small Animal Immobilon®
 Schedule II controlled substance; must be
under the authority of licensed veterinarian
Fentanyl
 Often combined with droperidol
(Innovar-Vet®)
 Readily reversible with naloxone
 Schedule II controlled substance;
must be under the authority of
licensed veterinarian
►
Carfentanil citrate (Wildnil®)
 Works well on the largest animals
 Readily reversible with naloxone
 Schedule II controlled substance;
must be under the authority of
licensed veterinarian
 Extremely dangerous for humans
if accidentally exposed
Dose Calculations
►
►
Several factors influence dose needed
 Animal species
 Mass
 Age
 Sex
 Psychological state
 Condition
Calculation
 Estimate animal mass
 Doses listed in mg of drug per kg body mass in reference
books
 Syringes loaded as ml drug, so mg/ml required
Formula for Calculating Volume
►
The formula is:
► Volume of Drug Administered =
►
Body Weight x Dosage
Drug Concentration
►
►
For example, consider immobilizing an animal that weighs 80 kg (176 lb) with drug
“X”. The recommended dosage of drug X for this animal is 5 mg/kg. The
concentration of drug X is 100 mg/ml. First, calculate the total mg needed for this
animal by multiplying the animal’s weight (80 kg) by the recommended drug dosage
(5 mg/kg):
►
►
Milligrams of drug X needed = 80 kg x 5 mg/kg = 400 mg
►
►
Then calculate the volume of drug solution to withdraw from the bottle by dividing
the total mg (400 mg) by its concentration (100 mg/ml):
Delivery Systems: Non-gun
► Hand-held
► Push
► Blow



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
syringe
pole or pole syringe (easily made)
gun
Limited size of dart
Limited delivery volume
Limited range, but accurate with practice
Reduced danger of impact trauma as compared to
air- and combustion-powered guns
Can be readily manufactured by user
Delivery Systems: Capture Guns
Air-powered gun
Pistol or rifle
Variable power on demand (manual bleed-off, etc.)
Can handle larger darts than blow gun
Longer range than blow gun
Can be accurate with practice
Impact trauma not severe if proper technique used,
but still potentially dangerous
Combustion-powered gun
Pistol or rifle
Variable powder charges available
Can handle large darts (6–10 inches)
Poor range with largest darts; extended range with
smaller darts
Accurate ;can be equipped with telescopic sights
Higher potential for impact trauma than previous
delivery systems
Dart Placement
The preferred areas for
intramuscular injection
are the large muscles
of the hindquarters or
the shoulder. In elk
and many other
ungulates, the area in
the rump where the
light hair meets the
darker hair is a good
aiming point.
Common Drugs and Their Antagonists
Drug classification
Drug name
Antagonist
______________________________________________________________________________
Paralytic
Succinycholine
None
Tranquilizer/Sedative
Acepromazine
None
Tranquilizer/Sedative
Diazepam
Flumazenil
Tranquilizer/Sedative
Midazolam
Flumazenil
Tranquilizer/Sedative
Azaperone
None
Tranquilizer/Sedative
Xylazine
Yohimbine, tolazoline,
atipamezole
Tranquilizer/Sedative
Medetomidine
Atipamezole
Cyclohexane
Ketamine
None
Cyclohexane
Tiletamine (in Telazol®)
None
Opioid
Carfentanil
Naltrexone, naloxone
Opioid
Thiafentanil
Naltrexone, naloxone
Opioid
Sufentanil
Naltrexone, naloxone
Opioid
Butorphanol
Naltrexone, naloxone
Opioid
Etorphine
Naltrexone, naloxone,
diprenorphine
Moose immobilized with only opioids (carfentanil, thiafentanil,
etorphine) invariably remain sternal with head up. The addition
of a tranquilizer increases the probability of pneumonia because
moose have a tendency to roll over and aspirate rumen contents.
Resources (web sites) for Supplies
Animal Care Equipment and Services,
Inc.
www.animal-care.com
(Dart guns, darts, blow pipes, other
animal capture equipment)
Dan-Inject
http://www.daninjectdartguns.com/
(Dart guns, darts, blow pipes)
Palmer Chemical & Equipment Co., Inc.
www.palmercap-chur.com
(Dart guns, darts)
Pneu Dart, Inc.
www.pneudart.com
(Dart guns, darts, blow pipes)
Telinject USA, Inc.
www.telinject.com
(Dart guns, darts, blow pipes)
Wildlife Pharmaceuticals, Inc.
www.wildpharm.com
(North American supplier of capture
drugs)
Recommended Dosages for Ungulates
Species
Immobilizing dosage
Antagonist
_______________________________________________________________________________________________
Bison
0.005 mg/kg carfentanil plus 0.07 mg/kg xylazine
0.5 mg/kg plus 1 mg/kg tolazoline
Caribou
2.5 mg/kg ketamine plus 0.25 mg/kg medetomidine 1.25 mg/kg atipamezole
Deer, mule
4.4 mg/kg Telazol® plus 2.2 mg/kg xylazine
2 mg/kg tolazoline
Deer, white-tailed
4.4 mg/kg Telazol® plus 2.2 mg/kg xylazine
2 mg/kg tolazoline
Moose
0.01 mg/kg carfentanil
1 mg/kg naltrexone
Mountain goat
0.035 mg/kg carfentanil
3.5 mg/kg naltrexone
Pronghorn
0.05 mg/kg carfentanil plus 1 mg/kg xylazine
5 mg/kg naltrexone plus 2 mg/kg
tolazoline
Bighorn
0.05 mg/kg carfentanil plus 0.2 mg/kg xylazine
5 mg/kg naltrexone plus 2 mg/kg
tolazoline
Recommended Dosages for Mustelids
Species
Immobilization dosages
____________________________________________________
Ferret
35 mg/kg ketamine plus 0.2 mg/kg diazepam
Fisher
Marten
Mink
Otter
Skunk
Weasel
10 mg/kg Telazol®
18 mg/kg ketamine plus 2 mg/kg xylazine
15 mg/kg Telazol®
4 mg/kg Telazol®
10 mg/kg Telazol®
5 mg/kg ketamine plus 0.1 mg/kg medetomidine
Recommended Dosages for Other
Small Mammals
Species
Immobilization dosages
____________________________________________________
Badger
4.4 mg/kg Telazol®
Beaver
10 mg/kg ketamine plus 1 mg/kg xylazine
Marmot
80 mg/kg ketamine plus 10 mg/kg xylazine
Muskrat
50 mg/kg ketamine plus 5 mg/kg xylazine
Opossum
10 mg/kg ketamine plus 2 mg/kg xylazine
Porcupine
5 mg/kg ketamine plus 2 mg/kg xylazine
Rabbit
30 mg/kg ketamine plus 6 mg/kg xylazine
Squirrel
10 mg/kg Telazol®
SUMMARY
► Drugs
and the equipment used to administer them have
become more sophisticated, efficacious, and safe over the
past half century.
► Today,
capture drugs should be part of every wildlife
management professional’s armamentarium.
► Although
capture drugs should be used judiciously, they
should always be considered as a primary solution to
problems where animal and human safety is uppermost.