As we know, rabbits have large ears! These ears have several critical roles including, hearing, thermoregulation and providing a source of lovely veins for catheterization!
Check out our post on venepuncture and catheterization here!
Huge ears!
Image source http://www.menageriefarm.xyz/rabbit-breed-info.html
As our bunny friends have huge ears, it’s no surprise they can be a huge problem! The large external ear (pinna) narrows down into a very narrow (stenotic) ear canal, which can be especially pronounced in lop eared rabbits. The ear canal is made of three cartilages – auricular, annular and scutiform cartilages. The auricular cartilage (the whole large ear!) is much bigger than the small straw like tube structure that is the annular cartilage, which is a few centimeters long at most. Due to this size mismatch, the ear canal collapses slightly and is narrowed. Which also helps trap cerumen, debris and moisture down near the tympanic membrane.
By using an otoscope (or in some cases endoscopy during a general anaesthetic), you can possibly visualise the narrow canal, with yellow cerumen possibly trapped near the ear base. It’s important to attempt to differentiate this cerumen and debris from purulent exudate with cytology and even culture and sensitivity tests!
Rabbits can have incidental otitis externa, or much like dogs, can present to your clinic with head shaking and scratching at the ears. Occasionally you may see pruritus or crusting of the ear with Otodectes “ear mite” infections.
Management of Otitis Externa
Medicine
The recommended treatment of otitis externa, depends on the causative agent. Most commonly this is:
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Otodectes cuniculi (Psoroptes cuniculi ) ” Ear Mite” – We aren’t here to argue scientific names, but ear mite may appear as either!
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Bacteria
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Ear mites
You can see more about ear mites here!
Parasiticides safe for use in rabbits include –
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Ivermectin
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Selamectin (Revolution)
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Imidacloprid/moxidectin (Advocate)
For doses, check out our rabbit formulary for vets at exoticsvets.com/rabbit-formulary/
You will need a password, and to be a vet! If you need the password, email us at exoticsvets@gmail.com
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Bacteria
Common bacteria involved in otitis externa in rabbits include:
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Staphylococcus aureus
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Pasteurella multocida
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Pseudomonas aeruginosa
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Bordetella bronchiseptica
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Escherichia coli
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Proteus mirabilis
Before treatment, culture and sensitivity should ideally be performed on cerumen and exudate in the ear canal.
If this is not possible, then bacterial infections require treatment with a broad spectrum antibiotic, with anaerobic coverage. Options include:
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Penicillin – best choice, not oral!
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Enrofloxacin
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Cephalexin – not oral!
For doses, check out our rabbit formulary for vets at exoticsvets.com/rabbit-formulary/
You will need a password, and to be a vet! If you need the password, email us at exoticsvets@gmail.com
Topical ear ointments or drops are generally not recommended in rabbits due to stenotic ear canals, especially in lop eared rabbits. The moisture of these solutions can get trapped in the ear, creating the ideal warm moist environment for infections, and slowly can cause ear maceration.
Otitis externa can be a source of pain for rabbits, and it may be necessary to include a combination of meloxicam and opioids to keep your bunny patient comfortable and make a complete recovery!
Unfortunately, due to the anatomy of rabbit ears, and the chronic nature of otitis externa in rabbits, often the only option is…
Surgery
Here is often where i’d recommend the enthusiastic or general practitioner veterinarian take steps towards resolving the problem. However, the best advice here is referral.
If you have chronic non resolving otitis externa with medical management, then your only option is surgery. Due to the close proximity of the facial nerve and also rabbits predisposition to problems with pain, then i’d HIGHLY recommend referral to an experienced rabbit practitioner or surgeon.
If you have one at your disposal, or want to recommend options to your client and bunny patient- here are the surgical options for chronic non resolving otitis externa.
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Partial ear canal ablation – PECA
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Total ear canal ablation – TECA
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Lateral Bulla Osteotomy / or Ventral Bulla Osteotomy – to prevent or currently treat Otitis media and Otitis interna
Hop home points!
If you are presented with a rabbit with Otitis externa, do your best to provide analgesia, keeping your bunny patient comfortable, and treat the source of the infection!
If you are unable to resolve the otitis medically, or if the infection is too chronic, then referral for surgery is your bunny’s best option!
Hop to it!
References
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Mancinelli, E & Angela ML, ‘Management of Otitis in Rabbits’, Journal Of Exotic Pet Medicine, 2017, 26, pp. 63-73.
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Chow, E et al. ‘Total ear canal ablation and lateral bulla osteotomy for treatment of otitis externa and media in a rabbit’, Journal Of The American Veterinary Medical Association, 2011. 239, 2, pp. 228-232
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Csomos, R et al. ‘Surgical Management of Ear Diseases in Rabbits’, The Veterinary Clinics Of North America. Exotic Animal Practice, 2016. 19, 1, pp. 189-204.
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MRC. Rabbit Clinical Manual. Melbourne Rabbit Clinic. 2018.
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Skinner, G. The diagnosis and medical management of ear infections in rabbits. UPAV Newsletter. 2018.
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