Ear mites are tiny, wingless, external parasites that live in the ears of horses and cause psoroptic mange. They are round with eight legs and are sometimes visible to the naked eye. They do not burrow into the horse but rather feed on the skin’s secretions.

Ear mites favor cool, humid environments. They are more likely to infect horses that have a pre-existing health condition, are immunosuppressed, or are otherwise stressed.

Mites are directly contagious between infected animals and spread easily between horses living in close contact. The ear mite can survive for a long time in the environment without a host, so transmission is equally likely through contact with infected equipment or premises.

The main symptom of ear mites in horses is itchiness of the ears, which can vary from mild to intense. Depending on severity, other symptoms may include crusty, swollen, smelly ears, damaged skin, extensive scabbing in the ear canal, brown discharge, and hair loss.

Diagnosis is typically based on physical and otoscopic examination and sometimes skin scrapings or swabs. Treatments include topical or oral parasiticides.

Prevention is possible with consistent grooming, adequate hygiene, and appropriate biosecurity and quarantine measures when a case is identified and when introducing new horses to the herd.

Ear Mites in Horses

Ear mites are wingless, light colored, parasitic arachnids from the family Psoroptes that live in the ears of horses and other animals and cause psoroptic mange. [1][2][3] An infestation of ear mites is called otoacariasis. [1]

The ear mite is tiny, measuring 0.4 to 0.8 mm from head to tail. [1][4] It is considerably larger than its cousins, the Chorioptes and Sarcoptes mites, as it can sometimes be seen by the naked eye. [1]

The ear mite has piercing mouth parts, with a round abdomen and eight legs, two sets of which point backwards from the body and two sets of which point forwards. [2] Females are differentiated from males by which set of legs carry the suckers they use to adhere to their host. [2]

Unlike other external parasites, such as lice or ticks, ear mites do not burrow into the skin but rather feed on skin secretions. [1]

Ear mites are not host-specific, which means that they can move from one type of animal to another. [1]

Psoroptes Mites

Previously, different types of Psoroptes mites were categorized as different biological classes based on which area of the body they infest. This classification has now been revised and all of the subspecies are now considered a single genus. [2]

The different genera of mites making up Psorpotes are all genetically consistent with each other, but typically live on different parts of the body. [1][2]

The species of mite that is usually found in the ears is P. cuniculi (also known as P. Hippotis). [3]

P. (equi) ovis is more likely to be found on the mane, axillae (the area that corresponds with the armpits on a human), base of the tail, or between the hind legs. [2] In extreme cases, these mites may spread over the horse’s back and sides. [4]

It is also possible for ear mites to live on other parts of the body if the ears are heavily infested. Conversely, body mites can make their way to the ears in rare cases. [1]

Ear Mite Life Cycle

The ear mite’s life cycle takes 10 to 16 days and has four stages: adult, egg, larva, and nymph. [2] All stages occur on the host (i.e. horse). [1][2]

The female lays eggs in the skin debris and they hatch within 2 or 3 days. [5] Egg production increases in winter as ear mites prefer cool, moist conditions and horses are typically kept together in close quarters at this time of year. [2][6]

How are Ear Mites Transmitted?

Ear mites do not fly and therefore cannot travel far. [1] They are transmitted through direct contact with an infected animal or indirectly by contact with infected premises or equipment such as blankets, brushes, buckets, tack, and grooming equipment. [1][6]

The survival time of a mite that is off its host is generally about 2 to 3 weeks but varies depending on the temperature and humidity of the local environment. [1] High humidity and low temperatures favour long survival times. [1]

Protected areas such as the corners of stalls, bedding, or organic debris are cool and hold onto moisture which can result in extended off-host survival times. [1] In very favorable conditions, ear mites can live without a host for up to 84 days. [1]

Ear mites are not host-specific, therefore horses can acquire an infection through contact with other animals such as goats, rabbi