Mites – Rabbit

Burrowing Mites

Sarcoptes scabei and Noetedres cati are known to parasitise rabbits especially overseas. Lesions are distributed mainly over the head especially at the base of the ears and occasionally over the body. Harrenstien et al (1995) describe tan, crusty lesions on the rabbit's face and outer pinnae and state that these mites are zoonotic. Both produce an intense pruritus. Diagnosis is by microscopic identification of the organism.

Treatment

Soll (1989) stated that two injections of ivermectin seven days apart were effective in eradicating sarcoptic infestation and that two injections (dose unspecified) eradicated Notoedres infestation. But selamectin (Stronghold®; Pfizer) may be a better therapy as it is used in cases of psoroptiasis in which a single dose applied topically for percutaneous absorption is known to be effective.

Non-Burrowing Mites

Cheyletiella parasitovorax

This mite produces mild to severe dry seborrhoeic lesions in rabbits, usually along the back from the neck to the scut, although severe infestations can spread to the belly and the vent.

There are many treatments:

• sulphide (Seleen®; Ceva Animal Health) removes the dander on which mites feed but does not act as an acaride. The environment should be thoroughly disinfested (10% boiling washing soda).
• ivermectin (Xeno 450; Genitrix) percutaneously, or Panomec (Merial) SC or IM, repeated fortnightly.
• 0.01% amitraz once a week for up to six weeks.
• Selamectin (Stronghold®; Pfizer) – ask the manufacturer’s veterinary advisers.

Refer the owner to the family physician for advice, as owner infestation is common.

Leporacarus gibbus

This mite is another superficial mite of pet rabbits which is not particularly pruritic, but frequently leads to parasitism of other pets in the same household. Treatment, and recurrence, is the same as with Cheyletiella spp.

Trombicula (harvest mites)

These may be found in rabbits. The larval form is parasitic.

Psoroptiasis

Otitis externa is frequently seen in pet rabbits and is due to infestation of the ears with the mite, Psoroptes cuniculi, and frequently secondarily infected with bacteria. Affected rabbits are presented with much dry, scaly matter in one or both ears, in which the mite can be seen on microscopy after in vitro clearance with potassium hydroxide. Affected ears give off a bad odour (Okerman 1994).

Chronic pruritic seborroeic otitis is usually associated with yeasts (Candida sp) whereas purulent otitis, especially where the discharge is tacky and sticky, may show E. coli and Pseudomonas sp on culture.

There is a significant increase in the incidence of psoroptiasis in amputees due to the inability of being able to perform aural hygiene satisfactorily (Rees Davies 2005).

Treatment of psoroptiasis in rabbits: DO NOT TOUCH! VERY PAINFUL!

• Ivermectin: repeat treatments every 15-17 days. Note that the vents can also be affected, in both sexes, especially in the lateral clefts. (Scaliness of the vents must be differentiated from treponemiasis in which the scaliness is not nearly so pronounced and in which no mites are detected by microscopy). Burke (1992) says that drops of 1% ivermectin may be applied to each ear as a routine even if the mites are not seen and seems to reserve systemic use of ivermectin for severe cases. Selamectin (Stronghold®; Pfizer) at a single dose administered percutaneously is also effective.