Chorioptes equi: Itchy leg mite

General Description: The adult mite is 0.4 mm. long, with an oval body and blunt mouth parts adapted for chewing skin debris and hair. Pretarsi are present.

Life Cycle: Mite life cycle stages are described in the overview. Chorioptes mites puncture the skin to suck lymph fluid. All stages of the life cycle occur around the edges of the oozing lesions. Generation time is 1.5 to 3 weeks, even in winter on heavily coated horses. The female Chorioptes lays up to 50 eggs over a period of 2 weeks. The mites may survive off the host in litter for up to 3 weeks.

Location: Found predominantly on the lower legs and feet, especially on the hind legs. Horses with long hair (feathers) on the fetlocks are particularly susceptible.

Geographical Distribution: Worldwide.

Significance: Infestations are usually not severe but may persist for long periods of time in herds.

Effect on Host: Known as chorioptic mange, or foot and leg mange. Foot mange mites irritate the skin, and the resulting serum ooze dries to crusts and scabs. The itching lesions do not spread rapidly or extensively but often become worse in autumn and winter. Infested horses bite, scratch, and stamp, especially at night.

Diagnostic Information: By identification of mites from skin scrapings.

Control: Treat infested animals, and separate horses from cattle, especially during winter months.

Chorioptes mite– adult