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Sweet itch, also known as insect bite hypersensitivity (IBH), is the most common allergic skin disease in horses. It manifests as chronically recurring seasonal allergic dermatitis.
After a long list of suspicious triggers in the past, including fungi, parasite larvae in the stomach, parasites in the skin, diet, climate, unsanitary conditions, kidney, liver or spleen dysfunction, too little exercise or food allergies, the Triggers identified and scientifically confirmed: proteins from the salivary gland that are produced during insect bites of the genus Culicoides spp . be transmitted. Culicoides spp. übertragen werden.
Insect saliva is a complex mixture that is released with its salivary gland proteins during an insect sting to prevent blood clotting. To date, more than 700 species of mosquitoes of the genus Culicoides have been described, of which about 130 are bloodsucking
Summer eczema is typically described as a classic type I allergy.
Although sweet itch is the best studied and characterized allergic disease in horses, treatment options are still poor and far from satisfactory. That is why we make it our task to put an end to the suffering by developing a vaccine that treats summer eczema therapeutically and prevent it prophylactically.
Clinical signs are severe itching, which leads to severe scratching of the base of the tail, mane, withers and stomach. This leads to hair breakage, lichen formation on the skin and crust formation. Affected lesions are characterized by thickening of the upper three layers of the skin, stratum corneum, epidermis, and dermis combined with fibrosis. In addition, there is evidence of acute inflammation, characterized by edema and inflammatory cell accumulation, located in perivascular clusters in deeper parts of the dermis.
Affected horses suffer from bald to bleeding wounds and sometimes even skin ulcers, which are caused by the severe itching, throughout the summer season. Mites, bacteria, or fungi can cause secondary infections in these lesions. This additionally promotes the infiltration of inflammatory cells into the affected lesions and accelerates the inflammation.
Since no mosquitoes of the genus Culicoides Culicoides have been found in Iceland so far , exported Icelandic horses are particularly susceptible and a disease prevalence of more than 50% has been observed for exports to Europe. The prevalence of summer eczema increases significantly with age. Horses introduced between the ages of seven and 15 have an extremely high risk of 96%. They usually develop eczema in their third or fourth season outside of Iceland.
Basically all races can suffer from sweet itch. In addition to Icelandic horses, it was mainly described for quarter horses, thoroughbreds, Arabs, warm-blooded horses, draft horses, Frisians, Shire horses and various pony breeds. Around 10% of horses worldwide are affected by sweet itch, while the incidence of diseases with the geographical distribution of Culicoides spp . related. Culicoides spp. zusammenhängt.
Although sweet itch is the best studied and characterized allergic disease in horses, treatment options are still poor and far from satisfactory. That is why we make it our task to put an end to the suffering by developing a vaccine that treats summer eczema therapeutically and prevent it prophylactically.
Recurrent urticaria, also known as nettle rash or hives, is a very common dermatological disease in the horse. The skin changes appear suddenly and can go away within a day. In some cases, however, the lesions persist for a long time.
The pathophysiology of urticaria in horses is very complex and has not yet been fully understood. Urticaria is a clinical symptom with a variety of possible causes. Both immunological and non-immunological triggers can lead to degranulation of mast cells and basophilic granulocytes, which results in the release of vasoactive and inflammatory mediators. This leads to increased permeability of the blood vessels, inflammation and loss of protein in the skin, which ultimately causes the typical skin changes
Immunological hypersensitivity reactions to injected (medication, insect bites), ingested with food or inhaled antigens occur most frequently. Physical triggers such as heat, cold or pressure are less often the cause of urticaria. However, increased exposure and unexplained idiopathic triggers can also lead to urticaria.
Typical symptoms are sudden edematous wheals on the skin and / or the mucous membrane. These wheals are mostly flat, steeply sloping nodes of various diameters that appear symmetrically on both sides of the neck, body and upper limbs. But they can also appear in the form of circular or serpentine-like wheals, linear, oozing or, if several wheals converge, as so-called “giant wheals”. They vary in size from about 0.5 cm to 15 cm. The wheals are typically easy to indent and the fingerprint remains in the skin for a few seconds. Itching can accompany it, while hair loss is atypical and only occurs with weeping wheals. Wheals,
Of all domesticated animals, urticaria is the most common in horses. All age groups can be affected, but horses 1-10 years of age are most commonly affected. There is no known gender predisposition. Thoroughbreds and Arabs are more likely to show urticaria due to inhaled antigens.
In horses, it is very difficult to differentiate between acute and chronic urticaria. Recurrent urticaria in humans is when the urticaria occurs at least twice a week for 6 weeks. In horses, the occurrence of urticaria at least twice or the recurrence of urticaria after cortisone therapy was recently defined as recurrent urticaria
Although most horses with urticaria respond very well to the use of cortisone or antihistamines, if the cause of the urticaria cannot be eliminated, they will often relapse once therapy is stopped.
The two inflammatory diseases of the lower respiratory tract "Recurrent Airway Obstruction" (RAO) and "Inflammatory Airway Disease" (IAD) have many similarities with human asthma. Therefore, the term equine asthma was recently introduced for these two diseases, in which the IAD represents the mild to moderate and the RAO the severe form of the disease.
Various influences, such as environmental factors, the attitude, the season and also preventive medical treatments contribute to the development of equine asthma. Horses that are kept in stalls with poor ventilation are exposed to high levels of dust particles, endotoxins, fungal spores, mold spores and harmful gases. Inhaling these allergens activates the immune system and causes inflammation of the lower airways. Since dry hay and straw can contain very large amounts of dust and mold spores, feeding them dry hay and straw is the greatest risk factor for the development or worsening of equine asthma. Another form of equine asthma is summer pasture associated obstructive pulmonary disease (SPAOPD), caused by allergens like pollen in spring and summer. The involvement of viral or bacterial infections in the development of equine asthma has not yet been clarified and there is still no scientific evidence of this.
Equine asthma causes inflammation and narrowing of the lower airways with increased mucus production. This leads to a structural remodeling and obstruction of the airways, which in the advanced stage can lead to an irreversible loss of lung capacity. Horses with IAD often show only mild clinical symptoms such as decreased performance or occasional coughing. The horses usually do not show any difficult breathing at rest. In contrast, horses with an RAO are much more severely affected. They show difficult breathing at rest (abdominal pressure), often cough in the stable and under exertion and show a clear performance weakness. Horses with an RAO often have whitish to yellowish nasal discharge. Body temperature can be increased during an acute asthma attack.
Lower respiratory tract diseases are the most common cause of underperformance in sport horses. Inflammatory diseases of the lower respiratory tract affect approximately 10-20% of all adult horses. The frequency and severity of the disease increase with age and housing.
Horses of all ages can get an IAD. However, younger horses are often affected. Whereas RAO only occurs in older horses (> 7 years).
The RAO develops over several years, which leads to an irreversible remodeling of the airways. In contrast, IAD can be completely reversible again. Not all horses that develop IAD inevitably get an RAO over time, but horses with an IAD are at increased risk of developing an RAO in the future
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