VETTECH U 2024 / HOUSTON, TX
OTITIS: INSIDE & OUT (CONT.)
Sponsored by
SATURDAY PM • SEPTEMBER 21
CHANTELLE HANNA, CVT, VTS (DERMATOLOGY) ANIMAL DERMATOLOGY CLINIC-CHARLOTTE
EXAM AND CYTOLOGY A bilateral ear exam should always be performed if the patient is amenable. There are 3 parts to the exam: examining the pinna for evidence of pathology or scarring, palpating the ear canals for symmetry and firmness (but use caution as may elicit a painful response), and lastly perform an otoscopic exam, which will allow you to assess what’s going on in the canal. Even if the patient has a history of unilateral ear disease or the client only reports one ear is affected, always examine both. You should be looking at all physical attributes of the canal, including, but not limited to, erythema, debris, stenosis, masses and hyperplasia. Can you visualize the tympanic membrane (TM)? What does it look like? Is it translucent and healthy or more opaque, white, or scarred? The TM should be flat. A bulging TM suggests there may be an accumulation of fluid or debris in the bulla, often seen with PSOM, in which there is a build- up of glue-like mucus in the bulla. Cytology is a MUST! Infection cannot be assessed by appearance or by odor. “It smells yeasty” is not a substitute for cytology. Always sample both ears. Using a cotton tipped applicator, swab both canals and place the samples on a slide in whatever method you’re comfortable with, either side by side (L and R), or next to frosted edge/slide end. Although heat fixing the slide isn’t necessary, it may help increase stain uptake by melting overly waxy samples. Stain it using Diff-Quik, a Romanowsky stain variant. You can use bibulous paper or a hairdryer to aid in drying. When looking at samples under the microscope, always start with low power using either the 4X or 10X objective, searching for fields that are likely to contain a diagnostic sample, before moving up to oil (100X). Record and quantify the presence of any bacteria (rods and/or cocci), yeast (Malassezia), or inflammation (neutrophils, degenerate neutrophils, nuclear streaming, macrophages, or eosinophils). Depending on the severity of the ear disease, other cells may be seen such as RBCs or lymphocytes. Occasionally, ectoparasites such as Demodex or Otodectes can be seen on
• Previous ear disease: Knowing if there is a previous history of ear disease can help pinpoint the primary factor. A long history of seasonal otitis may suggest an environmental cause. A non- seasonal history may suggest food, as well as environmental allergy as a potential cause. A long history may indicate the likelihood of many predisposing and secondary issues, such as stenosis or mineralization. Sudden-onset ear disease suggests something more along the lines of a foreign body, mass, or other incident. If a pet is adopted at an older age and history is sparse, there may still be signs indicating previous ear disease such as scarred pinnae from old hematomas. • Location and travel history: Certain parts of the country have native grasses that are notorious for producing grass awns that have a knack for becoming aural foreign bodies. If you aren’t in an area where these grasses are endemic, remember to ask if they have traveled to one recently? • Concurrent symptoms: Are there any signs of vestibular disease like loss of balance, facial nerve paralysis, or a head tilt, whether current or historical? This could be indicative of a deeper issue than just otitis externa. In the case of cats, it’s helpful to know if there’s a history of upper respiratory symptoms or evidence of herpes virus, such as runny eyes. These viral diseases can cause inflammation affecting the ear canal that may lead to inflammatory polyps. Finally, you’ll want to know if there are any other signs of allergic disease. Does the pet experience generalized pruritus (itch) or lick their feet? • Ear treatment regimen: Knowing what the client is putting in the ear, either currently or previously, is important for so many reasons. At the minimum, it will give you an idea of what the client feels has worked in the past and what hasn’t. Is the pet having a reaction to a topical ear treatment? Are they cleaning too frequently and causing the canal to stay moist? Are they using cotton swabs and have accidentally created a ceruminolith by pushing cerumen down against the tympanum? Or worse, did they lose the tip of the swab in the ear and it’s become a foreign body?
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