Order: Astigmata (Sarcoptiformes)
As well as the Order Astigmata, the Subclass Acari consists of the Order Ixodida containing the hard ticks (Family Ixodidae) and soft ticks (Family Argasidae), and several other Orders (Mesostigmata, Prostigmata and Orbatidae) containing the parasitic and free-living mites. Other members of the Order Astigmata of importance in veterinary medicine include Otodectes, Psoroptes and Sarcoptes.
In Canada, Chorioptes mites are found on cattle, horses and occasionally sheep. There is uncertainty if the mites on these various hosts are members of a single species, or whether each type of host has its own species. Even if they are all the same, transmission between host species seems not to be significant.
Host range and geographic distribution
Chorioptic Mange in Sheep
Chorioptes mites have been recovered occasionally from sheep in Canada. Lesions are most common on the lower limbs and feet, and sometimes occur on the scrotum, which may lead to temporary infertility.
Chorioptic Mange in Goats
Characteristics of Chorioptes in goats are as for sheep, except that apparently scrotal infestations have been less commonly observed.
Life cycle - direct
Life Cycle: Chorioptes bovis
Pathology and clinical signs
Treatment and control
There are several endectocide products approved in Canada that are effective for chorioptic mange in cattle: eprinomectin (EPRINEX), doramectin (DECTOMAX), ivermectin (VARIOUS) and moxidectin (CYDECTIN). Only the topical (pour-on) preparations are effective for Chorioptes. When using these products, it is essential to take note of milk withdrawal and slaughter delay requirements, if any.
Additional information on the products mentioned is available from the Compendium of Veterinary Products (Twelfth Edition, 2011), or from the manufacturers.
Effective control of Chorioptes bovis and chorioptic mange depends on the rapid isolation and treatment of infested animals, together with treatment of all contacts and, where possible, adjusting management practices to minimize transmission. This may include leaving areas housing infested animals empty for several weeks. Laboratory work, together with anecdotal evidence from the field, suggest that under favourable Chorioptes mites can survive and remain infective in the environment for days and perhaps for weeks.