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Selamectin versus ivermectin for Cheyletiellosis in pet rabbits

Clinical Scenario

You examine Flopsy, a 2 year old female entire Dwarf Lop rabbit with a skin problem. You diagnose Cheyletiellosis and explain to Flopsy’s owner that you will need to start a course of ivermectin injections to treat the mite infestation. Flopsy’s owner is keen to avoid injections if possible, as Flopsy gets quite distressed by trips to the practice, so she asks whether there are alternative treatments available. You remember reading about using a topical spot-on for treatment of mite infestations in rabbits, and wonder whether there is any evidence that this treatment will be as effective as the ivermectin injections…

3-Part Question (PICO)

In [rabbits with Cheyletiellosis] does the use of [a topical selamectin treatment compared with injectable ivermectin] result in [a better rate of treatment success]?

 

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

rabbit.mp. OR rabbits.mp. OR lapine.mp. OR oryctolagus.mp. OR exp Rabbits/

AND

cheyletiella.mp. OR cheyletiellosis.mp. OR fur mites.mp. OR walking dandruff.mp. OR exp Mite Infestations/

AND

selamectin.mp. OR Stronghold.mp. OR Revolution.mp. OR ivermectin.mp. OR Ivomec.mp. OR exp ivermectin/

CAB Abstracts 1910 to Present using the OVID interface

rabbit.mp. OR rabbits.mp. OR lapine.mp. OR oryctolagus.mp. OR exp rabbits/ OR exp oryctolagus cuniculus/

AND

cheyletiella.mp. OR cheyletiellosis.mp. OR fur mites.mp. OR walking dandruff.mp. OR exp cheyletiella/

AND

selamectin.mp. OR Stronghold.mp. OR Revolution.mp. OR ivermectin.mp. OR Ivomec.mp. OR exp selamectin/ OR exp ivermectin/

Search Outcome

MEDLINE

  • 41 papers found in MEDLINE search
  • 40 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from MEDLINE

CAB Abstracts

  • 14 papers found in CAB search
  • 13 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from CAB

Total relevant papers

1 relevant papers from both MEDLINE and CAB Abstracts

Summary of Evidence

Mellgren and Bergvall (2008) Sweden

Title:

Treatment of rabbit cheyletiellosis with selamectin or ivermectin: a retrospective case study.

Patient group:

53 rabbits with microscopically confirmed Cheyletiella infestation presented to two small animal clinics in Sweden. Rabbits were grouped in 3 categories based on their clinical records. Group 1 received ivermectin injections only, Group 2 received ivermectin injections and topical ivermectin and Group 3 received topical selamectin.

Study Type:

Retrospective case series

Outcomes:
  • Response to treatment as assessed by re-examination by the vet or telephone follow-up with owner. Rabbits were graded as in remission (no relapse during follow-up period); relapse (resolution of clinical signs more than 3.5 months after treatment but showing signs again during follow-up time); treatment failure (clinical signs did not resolve or recurred within 3.5 months of treatment)
Key Results:
  • The number of rabbits in remission were 9/11 (Group 1), 14/27 (Group 2) and 12/15 (Group 3)
  • The number of rabbits with a relapse were 1/11 (Group 1), 7/27 (Group 2) and 2/15 (Group 3)
  • The number of rabbits with treatment failure were 1/11 (Group 1), 5/27 (Group 2) and 1/15 (Group 3)
  • There was no statistically significant difference in response to treatment between the three groups (p=0.09)
Study Weaknesses:
  • The study was a retrospective case series which is not ideal for assessing treatment efficacy
  • No sample size calculation was carried out and the numbers of rabbits in each group was small therefore the study is likely to be underpowered
  • The study was reliant on clinical records which were not collected primarily for the study and so it is possible that important information was missing
  • Outcome was assessed following re-examination by the veterinary surgeon for some rabbits, but in other cases was assessed only via a telephone call with the owner. Less animals in Group 3 were assessed by the veterinary surgeon compared with Group 1 and Group 2, which may have affected the results
  • Two different clinics contributed cases to the study.  All but one case in Groups 2 and 3 came from one clinic, and all cases in Group 1 came from the other clinic.  This may have affected the results.
  • The dosage and frequency of treatments varied within groups 
  • No detail was given about the Chi-square analysis, and the p-value cut off used was not stated
Attachment:
Evidence appraisalEvidence appraisal

Comments

The study was a retrospective case series utilising clinical records of rabbits in two different clinics and is therefore not an ideal study design to examine treatment efficacy. Most rabbits in the two groups of interest (Group 1 and Group 3) had a good response to treatment, suggesting both treatments may be fairly efficacious. However, ideally an adequately-powered randomised controlled trial should be conducted to determine which of these treatments is most effective. In the meantime, veterinary surgeons should take into account their own clinical experience, client preferences and local licensing regulations when deciding on the most appropriate treatment.

Bottom line

Based on the available evidence, selamectin and ivermectin both appear to be equally effective in treating Cheyletiellosis in pet rabbits

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

Mellgren M, Bergvall K, (2008). Treatment of rabbit cheyletiellosis with selamectin or ivermectin: a retrospective case study. Acta Veterinaria Scandinavica 50: 1.

About this BET

First author:
Natalie Robinson
Second author:
Marnie Brennan
Institution:

University of Nottingham

Search last performed:
2015-12-14 16:44:59
Original publication date:
2015-12-23 16:44:59
Last updated:
2015-12-23 16:44:59
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