Ear mite infections in rabbits are relatively common, and may be seen at this time of year as a result of immunosuppression and stress following a long, cold, wet and windy winter.
Posted: 14 May 2018
The Psoroptes cuniculi mite is a non-burrowing mite that feeds on blood and serum. It has a life cycle of around 21 days, with eggs hatching after just 4 days. Many thousands of ear mites can affect the external ear canal and pinna, creating hyperkeratosis and a thick, dry, red/brown crust. Intense erythema develops as a result of the inflammation caused by the mucus and faeces from the mite. This in turn causes pruritis and head shaking, which is both painful and debilitating. It’s more common for just one ear to be affected and may be seen as a rabbit with a ‘dropped ear’, but in severely immuno-compromised animals, the infection can become more widespread affecting both ears, the neck, thorax, abdomen and perianal region.
Whilst it may be tempting to try and remove the thick crust, it’s generally not recommended as the procedure is very painful and will just expose a large area of bleeding, inflammed tissue.
Secondary bacterial and fungal infections are common if the problem is left untreated, so an early diagnosis and prompt action is recommended.
Middle ear disease secondary to a bacterial infection of the deep ear canal and rupture of the tympanic membrane can occur, in which case you’d normally expect to see a head tilt and loss of balance.
Clinical signs and visualisation of the mite with an otoscope will confirm your suspicions. It measures as much as 0.7mm in length and can even be seen with the naked eye. Skin scrapes and microscopic examination of the crusts will usually reveal the mite, larvae or eggs. KOH and liquid paraffin on the slide will help to break down the keratin and slow the mite movement down. If you get a chance show your client the mite under the microscope and it will convince that treatment is essential.
There are several reported effective treatments available in the UK, however we must stress you always follow the cascade to ensure compliance. The avermectins seem to be particularly effective, but are non-ovicidal and hence require repeated doses. Some examples of treatments used include;