Ear canker is caused by the ear mite Psoroptes cuniculi, a common parasite of rabbits worldwide. Head shaking, ear flapping, and scratching at the ears are common signs. Twisting of the head (torticollis) and spasms of the eye muscles may be seen.
Affected rabbits lose flesh, fail to produce, and succumb to secondary infections, which frequently damage the inner ear and may reach the CNS. Mites irritate the lining of the ear and cause serum and thick crusts to accumulate. With the rabbit well restrained or under general anesthesia, the brown crumbly exudate should be removed with cotton soaked in dilute hydrogen peroxide. The ear should be treated with any of the miticides approved for use in dogs and cats, or even with light mineral oil alone. Those products containing a cerumenolytic agent ( wax dissolving) are particularly useful in removing the heavy, crusty material.
The medication should be applied within the ear and down the side of the head and neck as well. Application should be repeated every other day for 6-10 days; additional treatments may be necessary. Hutches must be carefully cleaned and disinfected. Incidence is much lower when rabbits are housed in wire cages than in solid cages. The mite is readily transmitted by direct contact.
Ivermectin has been reported to be effective in treating ear mites.