Anesthetic:
suppresses sensory stimuli such as pain, feeling of heat or cold; local
or systemic effect.
Inhalant anesthetics (gases) or noninhalant anesthetics applied
by injection.
Analgesics:
primarily suppressing pain, central effect (for instance morphine)
Tranquilizer:
calming down the animal, no anesthesia
Muscle
relaxants = paralytic drugs: effect only on muscles, usually applied
in combination of diminished doses of anesthetics to prevent seizures (Example:
curare)
Ryder, 1978, tested
drugs used for animals by trying the effects on himself; after an experimental
dose of the tranquilizer Chlorpromazine for instance he was lying
on his bed, believing that for an observer he might look tranquil and content,
but he was just miserable. Ryder for instance regards muscle-relaxing drugs
paralyzing without diminishing consciousness as inhumane, causing terror
and trauma in the animal. He also notes considerable species differences
in a variety of drugs, warning that a drug humane in one species may be
inhumane in another one. 83
Anesthesia in lorises and pottos
Anesthesia in lorises is apparently difficult
32.
In a field study on slow lorises, in 5 of 12 cases (seven attempts with
Tiletamine/Zolazapam,
four attempts with Ketaminhydrochloride) the effect of anesthesia
was insufficient, the animals were only slightly benumbed or fully awake.
Males apparently needed a higher dosage, independent from the anesthetic
agent 80. Pottos, too, are "notoriously
difficult to anesthetize for surgical treatment", probably due to their
low basal metabolic rate 81.
Anestesia with Ketamine may cause an increase
of body temperature for up to 10C 67.
For anesthesia for taking of blood samples, use only of Ketaminhydrochloride
is recommended because additional tranquilizers can influence the result
2.
Anesthetic agents and dosages
used:
Ketamine
(from
Ketaset, Fort Dodge Laboratories Inc., Fort Dodge, lowa, 50501 USA) 61,
used
in slender lorises and lesser slow lorises (effect not documented)
61,
in slow lorises: dosage 10-25 mg/kg
61.
Imalgène 500 (Ketaminhydrochloride from Rhône
Mérieux, Lyon, France) 80,
used in slow lorises (N. c. coucang) in the field; none of the
treated animals showed signs of health problems during or after anesthesia.
Slower onset of effect than in Tiletamine/Zolazapam. Maximum dosage of
30 mg/kg recommended (Bonath, pers. comm., quoted in 80).
A dosage of 12.5 mg/kg led to slightly slower movements in one male and
one female and full anestesia for the reported interval 21 to 40 minutes
in one female. A dosage of about 22 mg/kg in another female caused full
anesthesia for the reported interval 0 - 20 minutes. A slightly higher
dosage than recommended by Bonath in two males had an insufficient effect,
only leading to slower reactions, a third male showed a satisfactory effect
for the reported interval 0 - 20 minutes 80.
Tiletamine/Zolazapam(from
Telazol, Fort Dodge Laboratories Inc., Fort Dodge, Iowa, 50501 USA) 61,
used in Loris (effect not documented); dosage in lesser slow lorises:
5 - 28 mg/kg ("a wide range of dosages have been used but 8-12 mg/kg, is
the average dose used. Slow recoveries are associated with the higher dosages").
Dosage in slow lorises: 4-14 mg/kg 61.
Provides better relaxation than ketamine 61.
Zoletil 50 (Tiletamine/Zolazapam from Fa. Virbac, Carros, France),
used in slow lorises (N. c. coucang) in the field; none of the
treated animals showed signs of health problems during or after anesthesia.
Onset of effect clearly earlier than in Ketaminhydrochloride
Maximum dosage of 30 mg/kg recommended (Bonath, pers. comm., quoted
in 80), one attempt in a male with a lower
dosage of 12,5 mg/kg led to no visible effect, three females treated with
the same dosage showed a full effect for about 40 to more than 120 minutes
80.
Isoflurane(from
Aerrane, Ohmeda PPD Inc., Liberty Comer, New Jersey, 07938 USA) 61,
used in slender lorises, lesser slow lorises and slow lorises (no information
about dosage or effect) 61.
Recommendation for Loris
:
Xylazine (Rompun®, Bayer,
Leverkusen) in combination with ketaminhydrochloride (for instance
Ketamin
10%, WDT, Garbsen) 63.
Advantage: good suppression of pain
and good muscle relaxation by a low dose, dosage can be increased up to
satisfactory effect, the effect of xylazin can be abolished with Yohimbin.
(This, however, may lead to muscle seizures because the effect of ketamine
is not diminished).
Disadvantage: the injected dose cannot be adapted to needed dosage
as in gas anesthesia. Duration: about 1-2 hours (energy loss / cooling
down must be considered).
So far little practical experience, one
test in Loris with a dosage of 1 ml (50 mg) ketaminhydrochloride
and 25 mg xylazine per kg bodyweight 63,
one anesthesia in a N. pygmaeus successful 85.
Inhalation anesthesia with Methoxyfluorane (Methofane®,
Janssen-Cilag), may be better than Halothane or Isoflurane
because it is less toxic for the liver and less easily overdosed. Not yet
tested in Loris, only in rats and mice.
Advantage: dosage well adaptable, quick recovery (as in any inhalation
anesthesia). Anestesia without catching and handling is possible.
Disadvantage: detrimental to the liver.
Tranquilizers
Tranquilizers may reduce psychic stress and
have a muscle-relaxing effect; during transport, muscle-relaxation and
slower reactions caused by tranquilizers may cause problems because the
animals cannot react properly on shaking of the transport box, protecting
themselves from lesions84. Better effect
by beta-blockers (animal calmer, but reflexes not impaired).
Diazepam
(Valium) is an anxiolytic
and muscle-relaxing drug. Slender lorises usually take it without problems
when injected into a cricket or mixed with milk formula. At Ruhr-University
consumption of one drop of Valiquid 0,3 By Hoffmann-La Roche (1
ml = 30 drops contain 10 mg Diazepam) led to careless-looking behaviour
and, in some cases, play behaviour, with higher dosage equilibrium problems
occured. An effect of Valium lasting from 3 to 12 hours in primates
was recorded 82.
Two
very old, weak lorises who got Diazepam in milk formula before being
euthanized drank a little and immediately fell asleep 15.
Given before introduction of an excited male to a female, Valium
in two cases led to normal, peaceful behaviour, in other cases, however,
aggressive behaviour occurred even under a dosage causing equilibrium problems;
therefore, animals should only be introduced to each other when showing
no signs of excitement.
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