Page 18 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Dermatology
Peer Reviewed
Management of
Canine Otitis Externa
Otitis externa is a common clinical presentation in dogs. It can be very frustrating for clients when it becomes a recurrent problem. There are many challenges when managing otitis cases including identifying the primary cause for the otitis and owner compliance when administering treatments. This article will discuss the aetiology of otitis including primary, predisposing, secondary and perpetuating factors. It will also discuss a logical clinical approach that is required when approaching these cases, including in house laboratory tests such as cytology and how the findings can influence your treatment choices when managing these cases.
Key words: canine, otitis externa, cytology
Natalie Barnard BVetMed CertVD DipECVD MRCVS
European Specialist in Veterinary Dermatology
After graduating from the Royal Veterinary College in 2001, Natalie then spent two years in general practice before returning to the RVC to undertake a three year residency in veterinary dermatology.
In 2006 she attained her RCVS Certificate in Veterinary Dermatology followed by her European Diploma in Veterinary Dermatology in 2009.
Natalie worked at The Animal Health Trust and Langford Veterinary Services before joining the Highcroft Veterinary Referrals team in December 2018.
Introduction
Otitis externa is a common clinical presentation seen in first opinion practice accounting for approximately 10% of all cases seen (O'Neill
et al. 2014). Otitis causes significant pain and discomfort for our canine patients and when a canine patient has otitis this can have a negative impact on the pet-owner bond, making effective management of this condition especially important. Management of otitis is challenging as it can be fraught with difficulties including owner compliance when administering topical treatment, identifying the primary cause for the otitis and managing client expectations. This article will aim to discuss the aetiology, approach and management of otitis externa.
Aetiology of otitis
Otitis is a complex clinical presentation as many factors can be involved in its development, which can subsequently impact the way we manage this condition. The causes of otitis have been categorized in to four main groups as outlined below:
Primary factors
These are factors that will cause otitis directly and examples include allergic skin disease, ectoparasites, foreign bodies (grass awns), endocrinopathies and tumours. Allergic skin disease is the most common primary cause of otitis externa in dogs (Jaeger et al. 2010).
Secondary factors
These are things that do not cause
problems in a normal ear but lead
to a problem when there are already abnormalities within the ear canal.These are often the factors that we focus on when managing a case of otitis, such as bacteria and yeast.The common organisms that cause otitis in dogs are listed in Table 1. It should also be noted that reactions to medication and overcleaning can also be secondary causes of otitis externa.
Predisposing factors
These are the factors that make it more likely for otitis to develop as they cause changes in the microclimate in the
ear canal. Examples would include the following:
• Conformation of the ear canal; hairy ear canals, pendulous pinna, stenotic external ear canals.
• Excessive moisture: this may be attributable to swimming or grooming, or high humidity in the ear canal due to a pendulous pinna.
• Irritant treatments or over treatment; trauma from excessive cleaning may disrupt the ear’s normal cleaning mechanism.
Perpetuating factors
These are when chronic changes occur to the ear canal which make the case of otitis more challenging to treat. Examples include: otitis media, calcification of the external ear canals, stenotic ear canals, hyperplasia of the ear canals.
In any case of otitis, it is important to remember that a multitude of factors can be present and that unless all are addressed medical management of the case may be challenging.
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