Dermatologic diseases

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  • 1. Disease Brief Description Epidemiology Pathogenesis Clinical Signs Lesions Differential Diagnosis Diagnosis Treatment Control & Prevention Epitheliogenesisimperfecta (aplasia cutis) (aplasia cutis) *A congenital skin deformity. Foals are born with small to extensive areas where skin is missing. Secondary infection is common *The condition is fatal when extensive *One or more hooves may be deformed or absent *Obvious at birth as glistening red,well- demarcated discontinuities in the skin or mucous membranes *Small defects can be surgically corrected Nevus *This term is used for any area where skin is malformed, including abnormally pigmented spots. Some forms of nevi displace the normal structures of the skin, including hair follicles; thus, these patches are hairless *Defect occur in all species *Alopecic, with pigmented ,pitted surfaces *When not extensive, it can be surgically removed; otherwise there is no effective treatment Dermoid sinuses or cysts *These cysts are lined with skin. Exfoliated skin, hair, and glandular debris accumulate in the cysts, which can lead to infection. The cysts are found on the midline of the back and in rare cases are associated with spinal cord deficits *Occur in Thoroughbred horses *They are caused by failure of complete separation of the neural tube from the epidermis during embryogenesis *The lesions may be lateral or bilateral *Can be removed by surgical excision Follicular cysts Periauricular (dentigerous) cysts *Develop by abnormal hair follicle growth and by retention of follicular or glandular products *They may be congenital when the hair follicle does not develop normally *Although they are present at birth, they may not be recognized until adulthood Albinism *Always associated with pink or pale irises and with visual defects and increased risk of skin damage from solar radiation. Albinism is different from extreme white spotting. *Some animals with extreme piebaldism (spotted or blotched with black and white) or dominant white have associated neurologic anomalies or deafness in one or both ears. *Lethal white foal syndrome is one that results from breeding 2 Overo Paints. Vitiligo *Hereditary but not noticeable at birth. Complete remission may occur but is rare. It causes no other health problems. *Mostly seen in Arabian horses (Arabian fading syndrome, pinky syndrome). *There is no accompanying systemic or cutaneus pathology *Affected animals develop bleached splotches of skin that occasionally also affect the hair coat and hooves. *Most lesions are on face ,especially the muzzle or planumnasale or around the eyes *No treatment is available *Treatments used in people with vitiligo are unlikely to help

2. *The onset is usually in young adulthood Most splotches are on the face, especially the bridge of the muzzle or around the eyes. Color loss may wax and wane animals Hereditary equine regional dermal asthenia (HERD) *A condition in which the skin produces abnormal collagen and/or elastin. *Common in Quarter horses and Arabian cross horses. *The condition is often first noticed during training, at the time saddles and tack are first placed on a young horse. *Handling of the skin elicited a painful response and superficial trauma led to skin wounds.The skin was thinner than normal in affected areas,with thickened borders and harder fibrotic masses. The collagen fibrils were thinner and smaller,which created a loose arrangement of collagen within the deep dermis which contains a distinctive horizontal linear zone *Patches or large areas of loose, stretchy, fragile skin *Joint problems *Clinically there were bilateral asymmetrical lesions of the trunk and lumbar regions,where the skin was hyperextensible *Based on visible signs and testing of the collagen structure. *Wounds heal slowly or not completely Epidermolysisbullosa syndromes *These are a group of hereditary congenital defects that affect the attachments between the outer and inner layers of the skin. *Skin trauma results in dermal- epidermal separation and blisters that soon rupture, leaving glistening, flat ulcers. Blisters may be present at birth or develop within the first weeks of life. The most severe blisters are on the lower legs (with sloughing of hooves), mouth, face, and genitals. * Except for the simplex form, most occurrences of the disease are fatal. All 3 forms of epidermolysisbullos a have been reported in Belgian foals. *Most common on the gingivae,palate,lips,t ongue,and feet *Most severe lesions are on feet with sloughing of hooves, claws of footpads and oral mucous membrane and facial and perigenital skin(erosions) Airborne Allergies (Atopy) *While the horse's immune system normally provides protection for the animal, the immune system of some horses overreacts to the presence of one or more airborne allergens. *Airborne allergens can adversely affect the skin. *Allergy testing is also available in some areas. Allergy testing identify the specific allergens *Avoiding the allergen, if possible *Corticosteroids to control the inflammatory reaction. If a horse is allergic to dust in the environment *Feeding the horse hay lage or some 3. other feed with little dust may also help. *Conversely, if the horse has seasonal pollen allergies, it can be kept inside during the months when pollen is normally present. Food Allergies *Although documented cases are rare. For example, there are reports that certain types of grains or hay have caused hives in horses. In some cases, the food allergies were associated with high-protein food concentrates. - - *Trial or elimination diet *Strict avoidance of the food. ECTOPARASITES Parasite Brief Description Epidemiology Pathogenesis Clinical Signs Lesions Differential Diagnosis Diagnosis Treatment Control & Prevention The biting midges, no-see- ums, or punkies belong to the family Ceratopogondiae. *Culicoid hypersensitivity in Canada *Queensland itch in Australia *Kasen in Japan *Sweat itch *Sweet itch *Summer dermatitis *Culicoides spp are vicious biters and can cause intense irritation and annoyance. In large numbers, they can cause livestock to be nervous and interrupt their feeding patterns. These gnats tend to feed on the dorsal or ventral areas of the host; feeding site preference depends on the species of biting gnat. *They fly only in the warm months of the year and are most active before and during dusk. They feed often on the mane, tail, and belly of horses. *These flies also serve as the IH for Onchocercacervi calis; the microfilariae of this nematode are found in the skin of horses. *These flies also transmit the bluetongue virus in sheep and cattle. *Horses often become allergic to the bites, scratching and rubbing these areas, causing alopecia, excoriations, and thickening of the skin *Onchocerciasis *Nonseasonalderma tosis that is similar to sweet itch but usually is less pruritic and affects the head, neck, and belly. *Most often collected in the field and not found on the animals *Identification is probably best left to an entomologist. *Larvae may be attacked in their breeding grounds. Extension entomology personnel should be contacted for the latest approved recommendations. *Permethrin for the spraying of stables and horseboxes. *Topical insecticides such as pyrethrins (eg, cypermethrin or cyfluthrin), especially in pour-on formulations, may also be used to control these adult pests in large animals. *Black flies *Black flies feed on all classes of livestock, wildlife, birds, and people. *Distributed throughout the world in areas where conditions permit development of the immature forms. *Larvae nearly -Because of their tiny,serrated mouthparts, female black flies inflict painful bites.The ears,neck,head, and abdomen of cattle are favorite feeding 4. always are found in swiftly flowing, well- aerated water; shallow mountain torrents are favored breeding places. *They are particularly abundant in the north temperate and subarctic zones, but many species are found in the subtropics and tropics where factors other than seasonal temperatures affect their developmental and abundance patterns. sites Buffalo flies, Haematobiairritansexigua *The buffalo fly is a primary pest of cattle and water buffalo but occasionally feeds on horses, sheep, or wildlife. *It is distributed throughout northern Australia and New Guinea and is found in parts of southern, southeastern, and eastern Asia as well as Oceania; it is not found in New Zealand. * Its life cycle is similar to that of the horn fly; the adult leaves the host long enough to oviposit on fresh manure, where development occurs. The life cycle may take as few as 710 days, depending on weather conditions. *Buffalo flies irritate and annoy animals, usually biting about the shoulders and withers. Bite wounds may provide a site for screwworm (Chrysomyiabezzian a) infection. During hot weather, the flies move to shaded parts of the body. Affected animals suffer blood loss and are irritated by the flies; feed efficiency and production may be affected adversely. *It can be identified by their dark color, size (approximately half that of a stable fly), and bayonet- like proboscis that protrudes forward from the head. *Insecticides should be avoided in the treatment of buffalo fly populations. Many of the chemicals used to treat these flies result in meat residues. Buffalo flies have developed resistance to the synthetic pyrethroids and to some of the organophosphates. 5. The eye gnats or the eye flies (Hippelates spp) *They are very small (1.52.5 mm long) flies that frequently congregate around the eyes as well as mucous and sebaceous secretions, pus, and blood. They gather in deep shade, such as among densely planted shrubs or in the shade of a dwelling *In the desert and foothill regions of southern California, adult Hippelates flies are present throughout the year; they are annoying from April through November. During the peak months, they are noticeable in th