Dermatology 3 Flashcards
where does an otic exam begin? why?
- A thorough examination of the pet for chronic or recurrent otitis begins away from the ear. Examination of other body regions may alert the clinician to the presence of systemic disease.
how to examine the ear?
- The evaluation of the painful ear canal is often the most challenging part of the appointment.
- Examine the pinna for erythema and swelling.
- Check the regional lymph nodes.
- Is there debris in the orifice of the external ear canal?
- What is its character?
- Palpate the auricular cartilage for pain, calcification or thickening, and for the typical “clicking” sound associated with fluid in the canal.
when in an otic exam should we suspect an allergic etiology?
One should be highly suspicious of an allergic etiology if the pinna and vertical ear canal is affected with the horizontal ear canal and deeper structures being relatively spared.
Pinnal-pedal reflex - what does it point to?
82% of dogs with scabies have a positive pinnal pedal reflex; however, 6.2% of pruritic dogs without scabies will also have a pinnal pedal reflex.
what may we have to do before scoping in an inflammed ear?
Before scoping, it may be necessary to treat the ear canal with anti-inflammatory doses of steroids for a week or two in order to relieve swelling and facilitate visualization of the ear canal.
how to clean otoscope cones
Soak cones for 20 minutes in Cetylcide® or 2% chlorhexidine before cleaning, drying and re-using.
In one study where, using sterile technique, two cones from each of 50 hospitals were swabbed and submitted for quantitative culture. Twenty-nine percent were contaminated! (6% with Pseudomonas aeruginosa and 4% with Staphylococcus pseudintermedius, among others).
most common reason for pet to resist otic exam, and how to avoid?
As the cone is advanced, be sure to avoid the luminal fold, the tissue at the junction of the horizontal and
vertical ear canal, as hitting this with the cone head is the most common reason for the pet to object to the exam. Point the cone in a slightly ventral orientation to avoid the luminal fold
Video-otoendoscopy use
more expensive than the hand-held devices but is a useful piece of equipment for a busy practice and almost a must in referral practice (required in ACVD training programs)
images can be saved and printed, allowing clients to see the pathology of the ear canal
Filling the ear canal with saline can further keep the tip of the camera lens from fogging; additionally, small
perforations of the tympanum may sometimes be visualized as air bubbles
Video-otoendoscopy is particularly useful when performing myringotomies, biopsying tumors or treating conditions such as Primary Secretory Otitis Media (common in the King Charles Cavalier Spaniel).
CT or MRI use for otic exam?
- are much more expensive imaging techniques but are much better at evaluating the ear patient than conventional radiography in the diagnosis otitis media/interna.
- CT is particularly useful in evaluation of bony structures
- MRI offers better soft tissue resolution than CT, but bone or calcification doesn’t have the same detail does CT
are most cases of otitis externa immediately curable?
client education?
Clients must be advised that most cases of otitis externa require chronic care. Frequent follow-up to monitor progress and repeat cytology is critical. Once the owner understands the need to control rather that cure and to elucidate the underlying cause for many of these conditions, the management will be far simpler and far less frustrating. The institution of a good management program will often keep the pet comfortable, and keep the owner satisfied with your veterinary service.
Otitis Externa: The three P’s
Primary factors, predisposing factors and perpetuating factors
otitis externa - Primary factors
- are direct causes of the otitis
- They produce inflammation of the ear canal epithelium, and the resultant clinical signs of disease
- Examples of primary factors include otodectic otitis, hypersensitivity (including contact allergy), disorders of cornification (e.g. primary seborrhea, sebaceous adenitis), endocrinopathies (e.g. hypothyroidism), immune disorders (e.g. pemphigus), and foreign bodies such as hair or grass awns (or even cotton swabs!).
Otitis Externa - predisposing factors
- are those that place the animal at risk for developing disease
- Examples of predisposing factors include conformation (pendulous pinnae, stenotic canals), excessive moisture in the ear leading to maceration of tissue (swimming, humidity), obstructive disease (tumours, polyps), systemic disease (pyrexia or other debilitating disease leading to immunosuppression) or inappropriate treatment (use of cotton tipped swabs to clean ears, inappropriate use or choice of topical cleaners, vigorous plucking of hairs from ear canal).
otitis externa - perpetuating factors
- Once the primary causes and predisposing factors work together to change the microenvironment of the ear canal, the perpetuating factors act to prevent rapid resolution of the condition
- Examples include bacteria (especially Staphylococcus pseudintermedius and Pseudomonas spp.), yeast (e.g. Malassezia pachydermatis), otitis media (a large percentage of dogs with chronic or recurrent otitis externa have had or have a ruptured tympanic membrane), and progressive pathological changes such as fibrosis, calcification, glandular hypertrophy or hyperplasia and so forth.
ear canal tumors - malignancy rate in dogs and cats, types
Cats:
◦ 87.5% of ear canal tumours are malignant
> Most common tumor: ceruminous gland adenocarcinoma
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Dogs:
> 60% of ear canal tumors are malignant
