Cheyletiellosis in rabbits is common. Treatment using ivermectin, selamectin, or moxidectin has been described, but no clinical studies have been published to support their use. This study examined the medical records of 53 rabbits with confirmed cheyletiellosis. The rabbits were divided into 3 groups: group 1 (n = 11) received ivermectin injections (mean dose, 253 µg/kg SC; range, 200 to 476 µg/kg) 2 to 3 times with a mean interval of 11 days; group 2 rabbits (n = 27) received an initial ivermectin injection (mean dose, 1044  µg/kg SC; range, 618 to 2185 µg/mg) followed by oral ivermectin (mean dose, 1324 µg/kg; range, 616 to 2732 µg/kg) given by the owners 3 to 6 times at 10-day intervals; group 3 rabbits (n = 15) received selamectin spot-on applications of 6.2 to 20.0 mg/kg, 1 to 3 times, at intervals of 2 to 4 weeks. Follow-up time was 4 months to 4.5 years. Group 1 results showed 9/11 rabbits (81.8%) achieved remission (free of clinical signs during the entire follow-up period), with 1 rabbit relapsing (free from clinical signs for more than 3.5 months, but showing signs again during follow-up), and 1 treatment failure. In group 2, 14/27 rabbits (51.9%) achieved remission, relapse was seen in 7 rabbits, and treatment failure occurred in 6 rabbits. In group 3, 12/15 (80.8%) achieved remission, 2 relapsed, and 1 treatment failed. There was no statistical difference among the treatment groups. All protocols were considered sufficiently effective and safe in treating cheyletiellosis in rabbits.

COMMENTARY: Cheyletiella does not seem to be very species-specific (including transiently affecting humans) and can live off the host in the environment for up to 10 days, so eradication of this mite is important. Recommendations for various treatments can be found in the literature and online, but as greater emphasis is placed on evidence-based medicine, it is good to have some clinical back-up of treatment efficacy. While this article is a good start, further prospective clinical trials with controls would be helpful. It would also be interesting to see whether a relationship exists (and if so to what degree) between immunosuppression and treatment failure, as has been suggested. It should also be noted that treatment of cheyletiellosis with selamectin in rabbits is still off-label in the United States.

Treatment of rabbit cheyletiellosis with selamectin or ivermectin: A retrospective case study. Mellgren M, Bergvall K. ACTA VET SCAND 50:1, 2008.