Home    Cattery            Staff            Contact             News      Exotics           Links    Information
                                                                           

HARVEST MITE INFESTATIONS

What is a harvest mite?

The harvest mite (Trombicula autumnalis) is a mite the larval stage of which causes considerable discomfort to cats and dogs during the late summer and autumn.  The mite is widely distributed in the British Isles but is particularly abundant in chalky areas and gardens where soft fruit is grown.

The six legged larval stage is the only stage which attacks warm blooded animals.  All other stages live in the environment and are not parasitic.  The larvae congregate on small clods of earth or on vegetation.  They are active during the day and particularly in dry sunny weather.  When a warm blooded animal comes into contact with the larvae they swarm onto it and attach onto skin particularly in sparsely haired thin skinned areas.  The larvae feed for 2 to 3 days and they drop off onto the ground to complete the life cycle.  The larval mite is orange and only just visible to the naked eye.

What effect do harvest mites have on cats?

The six legged larval mite attaches to the skin of cats to feed.  It fixes onto the skin by small hooked fangs and then injects fluid into the skin which liquefies cells.  The resulting liquefied food is sucked back by the mite.  The fluid injected by the mite is very irritant.  Irritation causes the cat to scratch, bite and lick which may result in extensive self-inflicted injury.  The resulting skin lesions vary from crusted spots to areas of hairloss to raw moist bleeding areas.

In cats mites are most commonly found on the ear flaps, on the sparsely haired area in front of the ears and between the toes but they can be found almost anywhere on the body.

Individual cats vary greatly in their sensitivity to mites.  Extreme sensitivity probably reflects the development of an allergy to the mite or its products and affected cats will cause severe self-inflicted damage to themselves.

How are harvest mite infestations diagnosed?

Sudden onset of intense irritation in July or August would make one suspicious that harvest mites might be involved although other ectoparasites and some forms of allergic skin disease can cause similar symptoms.

Your vet can make the diagnosis by identifying the mite.  Congregations of mites may be seen as intensely orange spots on the skin.  If fewer mites are present they may be seen on microscopic examination of a superficial skin scraping.

Diagnosis can be difficult if cats are presented some time after the problem started as by then the cat may have licked or scratched off all the mites.

How can I get rid of harvest mites from my cat?

Your vet will give you appropriate treatment.  There are no products licensed for the treatment of harvest mites in cats and dogs.  Insecticides licensed for on-animal flea control will effectively kill harvest mites provided that they reach the skin and not just the fur.  This is more readily achieved with a foam or pump-on liquid than with an aerosol spray or powder.  The problem is that unless the product has excellent residual action as soon as the cat returns to the infested environment it will collect more mites.  To avoid this the cat can be restricted to indoors during the mite season.  Fortunately there are now flea control products available with good residual action which may be able to prevent or considerably reduce reinfestation.  Such products should be applied to the cat during the harvest mite season (July to October) at the highest frequency suggested in the instructions.

What can be done to stop my cat itching?

In most cases treatment for the mites will rapidly make the cat feel more comfortable.  In cats which are very sensitive to mites additional treatment with anti-inflammatory therapy and occasionally physical restraints such as Elizabethan collars may be necessary to prevent further self-trauma.

Do harvest mites affect people?

People can be affected by harvest mites.  These are not caught from cats or dogs but from infested outdoor environments.  People's ankles become affected by walking through infested vegetation but more generalised lesions can follow sitting or lying in infested areas.  A typical human skin reaction consist of an intensely irritant rash.  Specific treatment is usually unnecessary.  Avoidance of infested environments is the best way of preventing the problem.