Sheep are generally healthy and economical farm creatures, providing wool, meat and milk. They do well in a variety of climates. Sheep flourish on grass, alfalfa and a few grains, and they clean up the pasture in wintertime after cows, as they graze much closer. Most sheep ear problems are related to life on a farm where they are contained, tagged and in close proximity to many other sheep.
Ear Tag Problems
Ear tags identify a sheep's farm of origin as required by the U.S. Department of Agriculture. When an ear tag is applied, the sheep's body tends to respond with an inflammatory reaction resulting in ear lesions. Metal loop tags are known to cause the greatest risk. Some sheep react badly to tag application and try to shake it off, causing their ears to haemorrhage. Older sheep have shown ear damage from tired tags that have torn out. To reduce infection, ear tags need to be applied under hygienic conditions and placed through the ear, avoiding the main blood vessel and cartilage and fitted in consideration of ear growth.
Ear Mites and Canker Ear
Like cats and dogs, sheep are also susceptible to those microscopic parasites known as ear mites. They lodge themselves in the moist soft tissue of the inner ear canal where they lay eggs and irritate their host, which cannot scratch them out. Mites spread from sheep to sheep through bodily contact. When the ear canal becomes packed with dead skin and pus, the advanced condition is known as canker ear. Ear mites can be treated with a topical solution containing pyrethrin, an insecticide derived from chrysanthemum flowers and known to be fast acting on unwanted insects.
Sheep get irritated when their ears are infested with mites. They can shake their heads violently; rub against rough surfaces such as wooden posts and wire fencing in an attempt to rid themselves of the pests. As a result the outer ear flap can become damaged as it bangs against the side of the sheep's head or other objects and forms a hematoma. The outer ear can permanently swell and deform resembling a cauliflower. Scabs and bloody scars often line the base of the ear and the external ear cleft.
Fly strike occurs when flies are attracted by blood, tissue damage or the odour from an ear infection to a sheep's ears where they repeatedly bite. Sheep can easily scrape their ears while trying to burrow under a wire fence to eat neighbouring blackberries, or while foraging amongst twigs in search of clover. Prominent ears like those on the Border Leicester breed type, which has very little fur to cover them, are easy targets for sunburn damage. As flies continue to bite, the irritation, blood and pus attract more flies. The sheep seeks relief by scratching the ear flap, causing further damage to the sensitive area.