Fur and Ear mites
By Robin Rysavy, DMA, in consultation with Noella Allan, DVM
A common problem often seen in rabbits is the presence of Psoroptes cuniculi (ear mites). These tiny parasites, a member of the arachnid family (includes spiders and scorpions), can cause intense suffering and illness if left untreated. Their life span is
approximately 21 days. Psoroptes cuniculi are non-burrowing, and chew and pierce the skin in the ear canal. Sometimes a rabbit caretaker will notice the accumulation of multiple layers of a thin, brown flaky crust on the inside ear of a rabbit. This crust is generally composed of mites, mites feces, skin cells, and inflammatory cells. Often a secondary bacterial infection will develop, which can extend to the middle and inner ear causing torticollis (head tilt) and ataxia (staggering or jerky, uncontrolled movements). In addition, with a severe infestation, the mites may extend to the head, neck, and other parts of the body. These mites cause intense itching, and often rabbits will scratch and shake their heads, which can lead to further trauma of the affected area.
Diagnosis is made by a rabbit veterinarian examining some of the debris from the ear canal under a microscope. Also these mites (and/or mite movement) can usually be seen with the naked eye through an otoscope.
The treatment most effective is a series of three to four subcutaneous injections of ivermectin at a dose of 400ug/kg, given at 2 week intervals. Ivermectin does not kill the mites eggs, but when used repeatedly at the apporpriate intervals and dosage, it will kill the new generations of mites as they hatch. All rabbits in the household should be treated (even if they are asymptomatic), as these mites are easily spread through direct contact with the affected rabbit, ear debris, or bedding. Psoroptes cuniculi can live for up to 21 days off the host, and will usually contaminate the environment as well when the layers of crusts in the ear dislodge. Therefore the area should be thoroughly cleaned.
Some of the newer topical parasite products such as Revolution claim to be effective against mites, but with the topical treatment, we did not see as good a "kill" as with the ivermectin. Any
secondary ear infection should be immediately treated with the appropriate antibiotic (systemic and topical). | |
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