Page 20 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Dermatology
Otoscopy
Ideally otoscopy would be performed
in all cases that present with otitis, but
in a dog with a painful ear this is not always possible in a conscious patient
and so consideration should be given
to anaethetising or sedating the patient
if required. Many patients are fearful of otoscopy and having their ear examined. If possible, we should try to make this a pleasant experience for the patient.The use of treats whilst performing otoscopy can be particularly helpful (Barnard and Foster 2017). Otoscopy is used not only to visualize the external ear canal and look for ectoparasites, but also to assess the integrity of the tympanic membrane. However, it is appreciated that assessment of the tympanic membrane may not always be possible in a dog with a painful ear full of discharge. Both ears should
Figure 3: Coccoid bacteria (yellow arrow) and degenerate neutrophils (green arrow) as seen on an ear cytology samples examined using the x100 oil immersion lens.
Although controversial, it is unlikely that systemic anti-microbial agents will reach therapeutic concentrations within the
ear canal, except in specific instances, which is why topical therapy should be the treatment of choice for the majority of otitis cases. In dogs with recurrent episodes of otitis externa, the challenge is identifying the underlying primary causes and managing these in conjunction with treating the infection that is present.
There are four main aims when treating otitis externa in dogs:
1. Identify and treat the infection present
including removing any debris or
discharge (secondary factors)
2. Reduce inflammation and pain 3. Identify the primary cause for the
otitis externa (especially important in
recurrent cases)
4. Prevent a recurrence of otitis externa
be examined for comparison, even if
one ear is unaffected.Always examine
the unaffected ear first if this is the case.
Sometimes cleaning the ear may be useful 1. Identify and treat the infection to enable a more thorough examination, Identification of the type of organism however any cytology samples should be causing the otitis will be achieved
Figure 4: Rod shaped bacteria (yellow arrow) and already discussed.This will enable the Subscribers
Cytology should be performed in all patients that present with otitis to determine the type of organism involved, namely coccoid bacteria (Figure 3),
Only
rod shaped bacteria (Figure 4) or yeast (Figure 5) (Malassezia pachydermatitis). This should ideally be performed prior to examining the ear with an otoscope as it if often better tolerated by the patient. Identifying the type of organism present enables us to make an informed treatment choice and decide whether to send a swab for culture and sensitivity.
Culture and sensitivity
Culture and sensitivity should be performed whenever rods are seen
on cytology samples to identify the specific organism involved. Care needs
to be taken when interpreting the sensitivity results as the majority of
cases will be managed with topical treatment which will be used at much higher concentrations than the MIC’s tested which are based on levels used in systemic treatments (Nuttall 2016). Other indications for sending a swab for culture and sensitivity include:
• Not being able to do in house cytology • No response to appropriate therapy
providing owner compliance has been satisfactory.
Figure 5: Malassezia pachydermatitis (yellow arrow) as seen on a ear cytology sample examined using the x100 oil immersion lens.
Management
of Otitis Externa
Most cases of otitis can be managed effectively with topical therapy by using polypharmacy ear drops (containing
an antibiotic, anti-fungal agent and a steroid) and ear cleaners.Topical therapy is still the mainstay of treatment for managing otitis as you can achieve high therapeutic concentrations in the dogs’ ear canal, providing the owners can administer the treatment successfully.
immersion lens.
the otitis pending any culture results.
As already discussed, topical therapy is
the treatment of choice and this will
be in the form of an ear drop and an
ear cleaner.The majority of topical ear drops contain three main components
an antibiotic, an antifungal and a glucocorticoid.Table 2 shows sensible antimicrobial choices depending on
the cytology findings. It should also be noted that good owner compliance is vital when managing these cases and so the formulation of the product dispensed should also be considered. Long lasting products are now available that can be highly effective at managing certain cases where coccoid bacteria and Malassezia have been identified on cytology samples.
All cases of otitis should be followed up with repeat cytology 10-14 days after starting treatment to ensure that the otitis has resolved, before treatment is discontinued.
Ear cleaners are vital when managing any otitis case as they not only remove debris from the ear but can also change the conditions within the ear canal to make the environment less favourable for the growth of organisms. In addition, the removal of mucopurulent
– manage any perpetuating or predisposing factors
taken before this is performed. using cytology and/or culture as
Cytology
degenerate neutrophils (green arrow) as seen on a veterinarian managing the case to make ear cytology sample examined using the x100 oil sensible antimicrobial choices to manage
Page 18 - VETcpd - Vol 7 - Issue 4