Flies
– why should your horse put up with them?
Flies
are not only a major irritation to horses, causing them to become stressed and
uncomfortable during the warmer weather but they also increase the risk of the
spread of disease. ‘A good fly control programme is highly advisable during the
summer, to help keep your horse happy and healthy’, says Zoetis vet Wendy
Talbot.
Ectoparasite
is the term used to describe parasites that affect animals externally, and horses
are prone to attack from many species, including house flies, horse flies,
black flies, blow flies, bot flies, mosquitoes, midges, lice, ticks and mites.
They can cause dermatitis, pruritic (itchy) conditions, lumps and skin lesions.
They can also cause conjunctivitis, headshaking contamination of wounds and
have the potential to spread other diseases. Biting midges, Cullicoides spp. can be a
particular bugbear as they are the cause of sweet itch. Mosquitoes are also well known biting pests. Over 30
species have been recorded in the UK, including those with the potential to
spread diseases such as West Nile Virus, a fatal disease that is luckily not
found in the UK at present.1,2 Flies
may also carry other parasites that can infect the horse such as Habronema spp. and Onchocerca cervicalis, which can affect the skin and in extreme
cases the eye.
Knowing the type of fly that is causing a problem can
be useful in deciding how best to control it. In general most flies thrive and
breed in warm, moist conditions such as on dung, rotting bedding or spilt feed
material. From these unsavoury places they can spread bacteria to the horse,
especially to vulnerable areas such as the eye and wounds.
The most effective way to control flies is with a
double-pronged approach of good management and a proven fly repellent or
insecticide. Frequent removal of droppings from the pasture and stable will
reduce fly breeding grounds, while keeping the muck heap well away from stables
and paddocks and keeping stables meticulously clean will reduce the risk of
flies bothering the horse. Fly rugs and facemasks are essential for many horses
in the summer and applying a fly repellent or insecticide to the rug can make
it even more effective.
As an owner it can be very difficult to choose which
fly product will work best for you. A repellent aims to make the horse less
attractive to the fly. An insecticide aims to kill the fly as soon as possible
after contact with no biting needed and can remain effective for up to four
weeks against some ectoparasites. For maximum effectiveness treatment should be
started before the fly season has begun, to control breeding, and continued at
regular intervals throughout the season.
The fact that insecticides have a medicinal function
by killing the insects, means they require a licence from the Veterinary
Medicines Directorate, to ensure their responsible, safe and effective use. Speak
to your vet or SQP about the most effective prescription insecticide available
for your horse.
“We would never put up with fly infestations so why
should our horses?” said Wendy Talbot. “If one product does not seem to work
well for your horse, consider a different formulation or ingredient. With a
repellent ensure that it has an HSE number or that it has been authorised by
the UK.”
