Download An improved method for restraining rabbits for examination of

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INVESTIGATIVE OPHTHALMOLOGY b VISUAL SCIENCE / October 1984
Key words: polymorphonuclear neutrophil, corneal epithelium, ulceration, wound healing, collagenolysis, electron
microscopy
From the Cornea Unit, Eye Research Institute of Retina Foundation* and the Department of Ophthalmology,! Harvard Medical
School, Boston, Massachusetts. Supported in part by NIH grants
EY-05718 (MDW), EY-03967 (KRK), EY-03306 (IKG), and the
Heed Ophthalmic Foundation (MDW). Submitted for publication:
April 9, 1984. Reprint requests: Dr. M. D. Wagoner, Eye Research
Institute of Retina Foundation, 20 Staniford St., Boston, MA
02114.
References
1. Cavanagh HD, Pihlaja D, Thoft RA, and Dohlman CH: The
pathogenesis and treatment of persistent epithelial defects.
Trans Am Acad Ophthalmol Otolaryngol 81:754, 1976.
2. Kenyon KR: Decision-making in the therapy of external eye
disease: Noninfected corneal ulcers. Ophthalmology 89:44,
1982.
3. Sendele DD, Kenyon KR, Wolf G, and Hanninen LA: Epithelial
abrasion precipitates stromal ulceration in the vitamin Adeficient rat cornea. Invest Ophthalmol Vis Sci 23:64, 1982.
4. Rivkin I, Rosenblatt J, and Becker EL: The role of cyclic AMP
in the chemotactic responsiveness and spontaneous motility of
rabbit peritoneal neutrophils. The inhibition of neutrophil
movement and the elevation of cyclic AMP levels by catecholamines, prostaglandins, theophylline and cholera toxin. J Immunol 115:1126, 1975.
Vol. 25
5. Gipson IK and Anderson RA: Effect of lectins on migration
of the corneal epithelium. Invest Ophthalmol Vis Sci 19:341,
1980.
6. Snedecor GW and Cochran WG: Statistical Methods, seventh
edition. Iowa State University Press. Ames, Iowa, 1980, pp.
144-145.
7. Pfister RR: The healing of corneal epithelial abrasions in the
rabbit: A scanning electron microscopic study. Invest Ophthalmol 14:468, 1975.
8. Berman M: Collagenase and corneal ulceration. In Collagenase
in Normal and Pathological Connective Tissues, Woolley DE
and Evansorf JM, editors. Chichester, England, John Wiley &
Sons, 1980, pp. 141-174.
9. Kenyon KR, Berman M, Rose J, and Gage J: Prevention of
stromal ulceration in the alkali-burned rabbit cornea by gluedon contact lens. Evidence for therole of polymorphonuclear
leukocytes in collagen degradation. Invest Ophthalmol Vis Sci
18:570, 1979.
10. Pfister RR, Nicolaro ML, and Paterson CA: Sodium citrate
reduces the incidence of corneal ulcerations and perforations
in extreme alkali-burned eyes—acetylcysteine and ascorbate
have no favorable effect. Invest Ophthalmol Vis Sci 21:486,
1981.
11. Gipson IK, Riddle CV, Kiorpes TC, and Spurr SJ: Lectin
binding to cell surfaces: Comparisons between normal and
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12. Fujikawa LS, Foster CS, Harrist TJ, Lanigan JM, and Colvin
RB: Fibronectin in healing rabbit corneal wounds. Lab Invest
45:120, 1981.
An Improved Method for Restroining Robbits for Exominotion of the Eye
Dovid M. Maurice and Tej Singh
Rabbits are strapped to a specially shaped platform with
their legs dangling over the sides. This system of restraint
allows freer access to the eyes for examination than other
methods and prevents the animal from injuring itself by
kicking. The animals appear to be quite relaxed and show
no signs of harm on release. Invest Ophthalmol Vis Sci
25:1220-1221, 1984
When the rabbit's eye has to be observed in the
slit lamp or a minor diagnostic procedure such as
applanation tonometry must be performed, it is necessary to immobilize the animal and to prevent
evasive movements of the head as far as possible.
The animal may be put under general anesthesia or
be tranquilized heavily, but this can upset the normal
metabolism, particularly if the observations or measurements have to be frequent or prolonged. Mechanical restraint is generally preferred for those procedures
that are painless but can alarm the animal. The same
is true for entering an ear vein with a needle and for
minor ocular interventions under local anesthesia.
Two forms of restraint are common. The first is to
confine the rabbit in a box with its head protruding
from a closure around the neck. This has several
disadvantages. First, the box blocks slit-lamp observation of much of the eye; second, if the animal is
frightened it will struggle and may injure itself; third,
it can jerk its head away when a needfe is inserted
into an ear vein, which requires reentry into a punctured and bleeding vessel. A more satisfactory procedure is to secure the animal firmly in a bag or
some other cloth wrap. This prevents it harming itself
and allows better access to the eye for observation.
However, it is not easy to wrap the rabbit successfully,
and this can be time-consuming, particularly if the
animal is recalcitrant. Moreover, it still can jerk its
head away on feeling a needle prick. We therefore
have developed a system of restraint that goes a long
way to avoid these disadvantages.
Materials and Methods. The basis of the system is
to make the rabbit lie on a narrow platform with its
legs straddling it. When its paws have no purchase
on a surface, it can only kick into the air, and its
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principal escape mechanism is circumvented. A 6mm-thick aluminum plate was cut to the dimensions
shown in Figure 1. This was supported about 20 cm
above a baseplate on a pillar, which was located
towards the rear (Fig. 2) so that the center column
of a slit lamp could be accommodated under the
head. The animal is held down by a Velcro strap in
the small of the back and another around the shoulders. The head-rest of a slit lamp was removed and
replaced with a platform arranged to bring the eyes
to the level of the optics. The wide part of the
platform supports the belly of the animal. Two side
pieces are attached to prevent the animal from listing
to one side if it is under general anesthesia; these are
not necessary when it is conscious, since it.maintains
its balance, but they do not interfere.
If further restraint is needed, the neck can be tied
down by a cloth ribbon or a narrow Velcro strip, or
a wider strip around the ears can be used to fix the
head.
Animals generally can be mounted on the platform
single-handedly, but this can be difficult if it is
resistant. The process is eased by the use of a loading
hopper. A narrow three-sided box, raised on a stand,
was constructed to accommodate the front extension
of the platform. The rabbit is placed in the top of
the box and is pulled out by the skin of the lower
back and its near legs pushed down to straddle the
narrow part of the platform. The rear strap is then
fixed firmly over the rabbit's back with the other
hand. The platform and the rabbit are then slid out
together until the front legs clear the box when the
second strap is placed in the same way.
Results and Discussion. There is as much freedom
to examine the animal's eyes in the slit lamp with
this method of restraint as is permitted by its anatomy.
It has been adopted in the laboratory for several
months and has been found advantageous by its
users.
The mounting procedure can be carried out successfully on the first attempt by an untrained person.
The rabbit can be secured for observation within 15
sec of lifting it from the cage. The neck does not
D
12.5cm
Fig. 2. Rabbit fixed in restrainer.
need to be tied for the purpose of examination in the
slit lamp. Although the animals rarely move their
heads when left alone, they become disturbed when
they are rotated about a vertical axis in order to
examine both eyes in turn. If this is to be frequent,
or if total stillness is critical, as in some forms of
fluorophotometry, it is convenient to use chlorpromazine as a tranquilizer.
Although the posture of the animal is unnatural,
there is no reason to suppose that it is physically
uncomfortable. The rabbits do not struggle or squirm,
although they can do so if deliberately frightened. On
the contrary, they generally appear to be quite relaxed;
some animals tense their leg muscles before they
become accustomed to the position, but this does not
result in their becoming dislodged. Some rabbits have
been restrained for up to 1 hr. Upon release, they
immediately hopped around in a normal manner, so
evidently there is no undue pressure on the vessels
or nerves of the legs.
We have not had much occasion to use the system
for venepuncture, but if the head is secured, the risk
of jerking away from the syringe seems to be reduced.
The engorgement of the veins can be assisted by
tilting the platform foward so that the animal's head
is below its body.
Key words: animal restraint, eye examination
-rvpiiiaT
l2-5cm
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11cm
Fig. 1. Dimensions of platform base.
14.5c
From the Division of Ophthalmology, Stanford University School
of Medicine, Stanford, California. Supported by NEI grant EY00431. Submitted for publication: February 27, 1984. Reprint
requests: David M. Maurice, Division of Ophthalmology, S030.
Stanford University Medical Center, Stanford, CA 94305.
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