Outdoor allergen avoidance and/or reduction

Avoiding offending allergens should always be considered, however due to the airborne nature of outdoor environmental allergens, this may not always be possible. An example of this would be pollens blowing across from plants in a neighbouring field. In these cases, your vet may also recommend treatment or therapy to control the symptoms.

Hints and tips

Pasture management options

  • Move the horse away from standing water, manure piles, compost piles, and sheep or cattle.
  • Restrict access to the edge of woodland, sheltered area (where wind will be reduced) and any marshy, mossy or boggy areas.
  • Stable during the relevant insect’s peak activity time period/s, for Culicoides this is dusk and dawn but for many other biting flies it is the middle of the day.

Horse management options

  • Use fly rugs and/or fly masks impregnated with a repellent such as permethrin covering the horse’s head, neck and tail base, or use a repellent in addition to using a rug
  • Make sure rugs and masks fit well and are free from tears, mud and faecal contamination as this will attract flies or allow them access
  • Ensure fly repellents are true repellents such as permethrin or similar (which stop the insects from approaching and biting) not just insecticides (which may kill after biting occurs).
  • Washes and sprays containing permethrin will need to be reapplied frequently if the horse gets wet or sweaty.
  • Tags and collars which help repel insects are also available can be tied into the mane and tail
  • Apply vitamin E to where permethrin is applied (typically under the mane and tail head) to prevent permethrin-induced paresthesia (burning or prickling sensation)
  • Some biting insects will not bite through layers of oil, so certain oil-based products may help by providing a barrier on the skin

Stable management options

  • Install large fans to circulate air within barns / stables as midges are poor fliers
  • Open windows and doors where possible covering with a fine meshed screen and use fly tape
  • Insecticide sprays released by a timer can be used within enclosed areas
  • Add fish to any ponds / permanent stagnant water to ingest insect ova and larvae
  • Use midge trapping machines in the immediate vicinity of stables or shelters

Meadow Grass

Grows on any soil, from sand to clay – will tolerate dry and damp situations. Plant of cultivated or waste ground. To be found on grassland, roadsides and paths throughout Britain. Has loose heads of flowers and seeds.

Flowering Season: May – September


Cocksfoot/Orchard Grass

A densely tufted grass with a few flowering stems. The pointed leaves, folded at first, open to reveal greyish green blades. Grass of meadows, pastures and roadsides throughout Britain. The leaves are rough edged and flat. Grows from 6 – 54 inches.

Flowering Season: June – September


Meadow Fescue

A tufted, deep-rooted perennial grass. Used in temperate regions of the British Isles for lawns and pastures. Related to the cultivated/garden species of festuca. Grows to 36 inches.

Flowering Season: May – September (peaks in June/July)


Red Top / Bent Grass

A dark green grass with long creeping stems. Common in fields and on roadsides. Creeping Bent Grass is sometimes cultivated for golf courses and amenity sites.

Flowering Season: May – September


Perennial Rye

Tough-stemmed native of waysides, rough ground and pastures. Also one of the most widely used species for re-seeding grasslands for grazing and hay-making. Has distinct well-spaced spikelets. Thrives on damp, rich soils and is found throughout Britain.Grows from 4 – 36 inches.

Flowering Season: May – August


Sweet Vernal

Forms tufts of stiff, smooth, unbranched stems and finely pointed flat leaves. Flower heads are spike-like with short branches. Grass turns from green or purple to yellow. Common on heaths, moors and pastures and in woods throughout the British Isles.Grows from 8 – 40 inches.

Flowering Season: April – July


Timothy Grass

Also called: Meadow; Cat’s Tail. Identifiable by their long silky heads. Some strains of the grass are exceptionally leafy. Thrives in heavy soil and is resistant to cold and drought. Common throughout Britain, it is used for grazing and hay. Can be found wild on roadsides and waste ground.

Flowering Season: May – September (peaks June/July)


Hints & Tips:

  • Try to exercise your horse on well-cut tracks and paths, or include road work where feasible, to reduce exposure to long flowering grasses and weeds
  • Keep paddocks and areas around arenas and stabling weed free
  • Regularly groom and bathe/rinse your horse, especially after exposure to long grass and /or on high pollen count days, this will help to physically remove some of the pollens on their hair
  • When your horse’s condition flares up make a note of where you have been and what they could have been exposed to. Keeping an allergy diary will help you to see any patterns over time.
  • Keep your horse stabled if possible when grass is being cut, crops are being harvested in the area and when the pollen count is high
  • Keep up to date with your local pollen reports by checking weather reports
  • Consider using a face mask or nose net when your horse is turned out
  • Be aware that species related to the named allergens may also prove problematic for your horse
The information supplied is intended for guidance only.

Daisy/Ox Eye

Member of the Daisy and Chrysanthemum families. Also called: Dog Daisy, Horse Daisy, Moon Daisy, Moonpenny, Marguerite. This is the most abundant and successful of all the flowering families. The Ox-Eye daisy has flowering stems up to 2 feet high which appear from rosettes of rounded and toothed leaves on very long stalks. The Ox-Eye daisy occurs throughout Britain and is common by roadsides, in meadows and cultivated fields.

Flowering Season: June – August


Member of the daisy family. Also called: Jack-piss-the-bed, Pissy beds, Pittley beds, Tiddlebeds, Dog’s Posy, Old man’s Clock, Peasant’s Clock, Swine’s Snout. Flowerheads are carried singly on unbranched and leafless stems which contain a sticky white juice. Common throughout Britain. The Lesser Dandelion grows in dry places; the Marsh and Broad-leaved marsh dandelion are common in wet places.

Flowering Season: March – October


Lamb’s Quarters

Member of the Goosefoot family. Also called: Muckweed, John O’the Nile, White Goosefoot. Toothed lower leaves, upper leaves often untoothed. There are fifteen types of Goosefoot growing in the British Isles including cultivated spinach and sugar beet. Very common on waste and cultivated land throughout the British Isles.

Flowering Season: July – September



Member of the Dock family. A tall dock, identifiable by its wavy, curled leaf-edges. Common throughout Britain in waste areas, waysides and cultivated land. Grows up to 3 feet.

Flowering Season: June – September




Member of the Plantain family. Also called: Fighting cocks, Short bobs, Soldiers and Sailors, Black Jacks, Hard-heads, Carl Doddies, Fireweed, Fireleaf. Flower stalk is deeply furrowed and leaves are erect and ribbed with 3 to 6 veins. Related to garden plantain or hosta. Common plant of roadsides and meadows. Grows 6 inches to 2 feet.

Flowering Season: April – September



Member of the Daisy family. Also called: Gipsy’s Tobacco, Muggar, Council Weed, Bollan Bane, Bollan Feaill. Perennial with an aromatic scent. Leaves are dark green on top and covered with white hairs underneath. Related to the garden plant, Wormwood. Common in waste places and hedgerows throughout the British Isles. Grows 2 – 3 feet.

Flowering Season: July – September


Red Clover

Straggling hairy plant. Leaves at the base of the stalk are large ending in long points. Bees are attracted by the strong sweet scent, and cross-pollinate the flowers. Red Clover is cultivated in the UK but also grows wild in grassy places. Grows up to 2 feet.

Flowering Season: May – October


Stinging Nettle

Member of the nettle family. Also called: Devil’s Plaything, Hokey-pokey, Jinny Nettle. Angular, upright stems. Stems and leaves are covered in stinging hairs. Common and widespread perennial weed. Natural habitat is fertile, muddy, slightly disturbed ground – especially amongst the lush foliage found in silt-rich river valleys and woodland glades. Grows 3 feet or more.

Flowering Season: June – September



Member of the Aster family. Also called: Bursages, Burrobrushes. The Common Ragweed has hairy stems and light green, lacy, leaves. The flowers are yellow/green, small and grow in clusters at the top of the plant up to 6 inches long. The Ragweed was most common in North America but is now found in the UK. Can be found by agricultural fields, urban landscapes, roadsides and near riverbanks. Can grow up to 5 feet.

Flowering Season: August – October

Oil Seed Rape 

Rapeseed (Brassica napus), also known as rape, oilseed rape, rapa, rappi, rapaseed is an annual or biennial herb which can grow up to 1.5m. The flowers are 4 petalled (typically cruciferous), bright yellow and approximately 2cm across. The leaves are greyish and the upper ones clasp the stem. Seeds are in a single row in cylindrical pods, which have distinctive beaks. The pollen of Oil-seed Rape is a potent allergen, which can cause serious allergic reactions in people and horses.

Flowering Season: April – September (but road side plants can last through to December.)


Small tree with furrowed brownish-black bark and short branches. Smooth twigs bear stalked buds and young leaves may be sticky. Fully developed leaves are dark green – almost hairless with flat or slightly notched tips. Catkins or tags appear in autumn and develop in spring before the leaves. Grows in damp woodland and by streams throughout Britain.

Flowering Season: February – April



Small tree with rough black bark near the base of the trunk and thin smooth white peeling bark above. Branches are drooping and bear hairless twigs and light green leaves with very pointed tips. Yellow catkins appear in autumn but do not open until the following spring. Common in woods and on heaths, but not chalky soils. Prevalent in the South and South East.

Flowering Season: April – May



Tall tree with a grooved grey trunk. Recognisable in winter by its hard black buds on smooth grey twigs, and in summer by leaves divided into several pairs of leaves. Groups of purple flowers appear before the leaves and soon turn green. Common in hedges and woods, especially damp areas on chalky soil in the North and West.

Flowering Season: April – May



A familiar, many-stemmed tree grown throughout Britain. Long yellow catkins appear in February and March. Common in hedgerows and shrub layers of lowland oakwoods. Can release pollen as early as January.

Flowering Season: January – April



Large tree with smooth grey bark, straight trunk and spreading branches. Brown winter buds are very long with pointed tips. Light-green leaves are fringed with long silky hairs when young. Long-stalked flowers. Casts a dense shade and will have little undergrowth. Native of the South-East but can be found throughout Britain.

Flowering Season: April – May



Found in damp places. Leaves are lance-shaped. Deciduous tree with simple leaves and small erect catkins. There are a wide range of wild and cultivated willows throughout the UK.

Flowering Season: March – May


Horse Chestnut

Large tree with sticky buds and palm-like leaves. Covered in clusters of either pink or white flowers in spring.After pollination, seeds appear encased in a prickly green shell which grow and release shiny brown seeds in the autumn, known as conkers.

Flowering Season: May – June


Scots Pine

Tall tree, “fir” shape when young, though older trees often have spreading of branches. Bark of mature trees is reddish, with bare patches where branches have fallen off. Twisted needle-like leaves are in pairs on short shoots along the twigs. Scots Pine, which is the only native Pine, is common in Scotland and parts of Southern England and is frequently planted in other parts of Britain.

Flowering Season: May – June



Large tree with rough, furrowed brown bark, crooked branches and knobbly twigs. Hairless leaves are short-stalked but the acorns (fruit) are on long stalks. Common in hedges and woods throughout Britain.

Flowering Season: April – May



Member of the Ash family. Almost evergreen shrub. Slender branches and very short hairs on young shoots. Masses of flowers with a strong unpleasant scent, followed by black berries in autumn. Common hedging plant in woods, hedges throughout the UK, and scrub land in the South of England where it is one of the characteristic shrubs of chalky soils.

Flowering Season: June – July



The sycamore is a deciduous broadleaf tree native to central, eastern and southern Europe. It can grow to 35 metres and live for 500 years. The bark is dark pink-grey and smooth when young, but becomes cracked and develops small plates with age. Twigs are pink-brown and hairless. Its leaves have five lobes and its flowers are small, green-yellow and hang in spikes. After pollination by wind and insects, female flowers develop into distinctive winged fruits known as samaras.

Source: http://www.arkive.org/sycamore/acer-pseudoplatanus

Flowering Season: April – September

Hints & Tips

  • Avoid areas with a high concentration of the named allergen e.g. beech woods.
  • Avoid exercising your horse on routes that pass by or through wooded areas.
  • Turn horses out away from wooded areas if possible
  • If there are trees in your horse’s paddock consider fencing the area to limit contact with the tree and fallen leaves
  • Keep hedges bordering paddocks well cut to avoid flowering.
  • Be aware that the pollen calendar is seasonal but often earlier than grasses or weeds although is dependent on species
  • Be aware that species related to the names allergens may also prove problematic for your horse. e.g. Privet is related to the ash family.
The information supplied is intended for guidance only.