Self assessment test: Selecting ear drops for dogs with otitis externa

Abstract

Ross Bond graduated fromGlasgow Veterinary School in 1985 and then spent five years in veterinary practice. He joined the Royal Veterinary College in 1990, where he is currently a senior lecturer and head of the dermatology service. He is a Diplomate of the European College of Veterinary Dermatology and an RCVS-recognised specialist in veterinary dermatology.Otitis externa is one of the most common conditions presenting in canine practice. Ear disease often reflects a combination of predisposing, primary, perpetuating and secondary factors. While the animal health industry has provided veterinary surgeons with a wide array of safe, effective and licensed topical products, simply dispensing ear drops will not satisfactorily resolve otitis externa in a significant proportion of cases. Veterinary use of antimicrobial drugs is currently under intense scrutiny, prompting the BVA to produce an eight-point plan on responsible use. This article discusses the use of antimicrobial products in canine otitis externa in relation to these guidelines, with emphasis on rational product selection and minimising antimicrobial use where appropriate. doi:10.1136/inp.e4891 Provenance: Commissioned and peer-reviewed mal health has prompted the British Veterinary Association (BVA), British Small Animal Veterinary Association and Veterinary Medicines Directorate each to produce their own guidelines and information on responsible antimicrobial use in veterinary practice. The present review considers otic product selection in relation to the points proposed in the BVA's eight-point plan, where relevant to the topical treatment of otitis externa. Work with clients to avoid the need for antimicrobialsMicrobial infection within the canine external ear canal often reflects proliferation of normal components of the skin microbiota (commonly Staphylococcus pseudintermedius or Malassezia pachydermatis) or invasion by environmental opportunistic Gram-negative bacteria such as Pseudomonas aeruginosa. Since ear infection is considered to be a 'secondary factor' in otitis externa that reflects the Otitis externa is one of the most common presentations in canine practice. In a survey of 3707 small animal consultations observed by veterinary students during clinical extramural studies (EMS) in general practice in the UK, otitis externa was diagnosed in 123 out of 559 dogs (22 per cent) with skin disease (Hill and others 2006). Eighty-eight of these received antibiotic-containing ear drops, although the proportion that received systemic therapy for otitis was not reported. Discussions with final year veterinary students about their experiences during EMS indicate that the rationale for selecting one otic product over another is often not clear to them (and perhaps not to the attending veterinary surgeon either). The survey by Hill and others (2006) indicates that product selection in skin disease is routinely empirical; out of 795 small animal dermatological consultations (including 151 cases of otitis), otoscopic examination was conducted in 90 cases...

Dermatology in Dogs and Cats

“…Factors that help to perpetuate otitis are bacterial infection (Staphylococcus pseudintermedius, Pseudomonas aeruginosa), yeast infection (M. pachydermatis) and complications of otitis media, as ear canal narrowness due to hyperplasia and calcification of the cartilage structures [151,153,154].…”

“…Gram positive bacterial infections can be treated with topical steroidal antibiotics (fusidic acid) and topical fluoroquinolones (marbofloxacin and orbifloxacin). Gram negative infections could also be treated with fluoroquinolones or with topical cationic polipeptides (polymyxin B) and aminoglycosides (neomycin, framycetin, gentamicin) [154]. Aminoglycosides are contraindicated in cases of tympanic membrane rupture due to their ototoxicity [150].…”

“…Aminoglycosides are contraindicated in cases of tympanic membrane rupture due to their ototoxicity [150]. Malassezia species are usually susceptible to azoles (clotrimazol and myconazol) and polyene macrolides (nistatin) [154].…”

“…Chronic or recurrent cases should be treated for, at least 4 weeks, and systemic anti-inflammatory drugs are recommended in association to the topical therapy (prednisone or prednisolone 0.5 mg/kg q12h) [158]. Glucocorticoids efficiently control the inflammation and may prevent or reverse tissue hyperplasia and canal stenosis [154].Therapy should be discontinued only when cytology is negative for microorganisms, if there is no ear canal edema and if the epithelium has a normal appearance [158].…”

A randomized placebo-controlled trial of the efficacy and safety of a terbinafine, florfenicol and betamethasone topical ear formulation in dogs for the treatment of bacterial and/or fungal otitis externa

“…Although it is considered good practice to evaluate results of ear cytology and microbial cultures, which, unfortunately, can yield discordant results [9], the selection of a topical ear formulation in general practice appears more often influenced by subjectivity, prescription habits, and commercial aspects of product supply [7]. …”