College of Veterinary Medicine

Small Animal DX & Therapeutic Techniques

Otoscopic Examination of the Dog & Cat


Equipment

components
handle
magnifying heads
cones
assembled otoscopes
instruments

ear_otoscope.JPG (27912 bytes) An otoscope consists of 3 parts:
  • a handle which contains the power for the light source
  • a head which contains the light bulb and magnifying lens
  • a cone which is inserted into the ear canel

The handle may contain removable batteries or may be rechargable.  Some handles are recharged by placing in a charger stand (the bottom of the handle pictured has a contact plate on the bottom which "connects" with the charger) or the bottom of the handle may unscrew revealing prongs to plug into an electrical outlet. The handle connects with the otoscope head by lining up notchs on both pieces, then rotating to "lock" the two pieces together.

The power is turned on to the handle by depressing and then rotating the small red button.

As the power begins to diminish, the intensity of the light will decrease, then the light goes out altogether. Keep the handles fully charged for maximum illumination.

Head 1 may be used both for examination and instrumentation in the ear canel. Head 2 has a larger magnification lens but the lens must be flipped out of the way in order to pass instruments through the otoscope, therefore this head is best used to view, rather than to instrument. Head 3 has two magnifying lens and is used when two individuals want to have the same view of the ear canel (student or pet owner).

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Magnifying heads

ear_head1.JPG (15482 bytes) ear_head2.JPG (15754 bytes)
Head 1 ( see assembled otoscope)
This head may be used both for examination and instrumentation in the ear canel but does not provide as great of magnification as does head 2. I prefer to examine the ear first with head 2, then change to head 1 if I need to pass an instrument into the ear canel.

Head 2  ( see assembled otoscope)
This head provides a greater degree of magnification than head 1. The entire magnifying lens can be piveted off the opening of the otoscope but then all magnification is lost. The lens tends to fog with condensation as it warms to the temperature of the animals ear. "AntiFog" eyeglass preparations can be applied to the lens or more simply, breathe on the lens to warm it before inserting in the ear canel.
ear_head3.JPG (20410 bytes) Head 3  ( see assembled otoscope)
This head is used when two individuals want to have the same view of the ear canel. It is used in a teaching setting or to show owners the ear canel of their pet. Because the light has to travel a greater distance before illuminating the ear canel (notice how long this head is compared to heads 1 and 2) the intensity of the light available to illuminate the ear canel is diminshed. Therefore use a one lens head to examine the ear canel before changing to the dual lens head.

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Ear cones

Ear cones are made of rigid plastic. They are available in different lengths and diameters. Use the largest cone that can be passed into the ear canel for best visualization. The diameter of the ear canel tapers as it approaches the tympanic membrane.  You may need to use more than one size cone to examine different depths of the ear canel. If you need to pass an instrument into the ear canel the cone tip must be wide enough to accomedate the instrument.

ear_cones.JPG (15126 bytes)

ear_cone_tip.JPG (16824 bytes)

The photograph below shows the narrowest tip of the cone (the end that is passed into the ear canel. Notice the rough edges of the wide, short cone on the left. This cone has been cut to use as a vaginal speculum to place a urinary catheter in a female dog.  This modified cone is too short to be of much use in examining ears. Check ear cones periodically to assure that the tips are smooth and not chipped or frayed (or intentionally modified). Damaged cones can be damaging to the ear canel.
Cones should be cleaned of wax and debris after use and cleaned with or stored in an antiseptic cleaning solution.

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Assembled otoscopes

ear_otoscpe_head1cone.JPG (13674 bytes)

Assembled otoscope using head 1.

ear_otoscope_head.2_cone.JPG (14958 bytes)

Assembled otoscope using head 2

ear_scope_head3cone.JPG (16820 bytes)

Assembled otoscope using head 3

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Instruments

ear_tools.JPG (16514 bytes) There are several types of instruments that can be used in the ear canel. Alligator forceps and an ear loop are the two I find most useful. The forceps are used to grasp and remove  formed debris from the ear canel such as foxtails or firm "chunks" of ear wax.

The loop has a "loop" of fine gauge wire at the tip. It is very useful to scrape debris from the ear canel, especially debris that is not well formed which breaks up when grasped with a forceps.

A plastic "tom cat" urinary catheter is another useful tool used during ear cleaning.

ear_scppe_instr.JPG (16729 bytes) Before placing the otoscope into the ear canel confirm that the instrument(s) you plan to use are of sufficient length to protrude beyond the tip of the ear cone and that the jaws of the alligator forceps can be opened.  Make note of the distance the instrument protrudes beyond the tip of the ear cone when the instrument is inserted into the cone as far as it can go. One often has a poor sense of depth perception when viewing a narrow canel like the ear canel. Knowing how far the instruments protrude beyond the tip of the ear cone can help reduce the chance of iatrogenic trauma to the ear drum.

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proceed to demonstration of examination

otoscopic exam main | otoscopic exam procedures | Diagnostic Techniques Laboratory
 


Revised February 02, 2009     |     Printer Friendly Version

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Last Edited: Feb 02, 2009 4:05 PM   

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