Scratches (sometimes called grease heel) is a skin infection most commonly found on the back side of the pastern, although other sites are possible. The areas involved may be crusty or moist and oozing. There may be swelling and if severe there may be lameness as well. Most cases will respond to fairly conservative treaments, including clipping the hair (as below), washing with antiseptics (we prefer betadine) and the application of any of a number of topical preparations (we formulate our own "scratches ointment" that works very well). Severe cases may benefit from systemic antibiotics. The areas should be kept clean and dry (a real challenge in Vermont mud season) and if there is swelling leg wraps are recommended.
Hives, as seen here and below, usually occur in response to an individuals immune system over-reaction to some type of allergen. These allergens may be ingested, inhaled, injected (ex: spider or other insect bites) or topical contact. The hives (also called wheals) may cause discomfort and itchiness. There may be few or cover the entire body. In severe cases there may be swelling of the face and eyelids and breathing may be compromised due to swelling of the larynx and lung involvement. Worsening signs and any breathing impairment should be considered emergencies and seen quickly. Treatment of hives generally includes systemic antihistamines,steroids and sometimes anti-inflammatories. Response to treatment is usually fairly rapid and dramatic. Most times the inciting cause of the reaction remains unknown.
Hives
Sarcoids (seen here and below) are the most common equine tumors and may occur in a variety of presentations and sites. About 1/3 of all equine tumors may be sarcoids. Their cause is unknown but there may be a viral origin as well as a hereditary component. Surgical excision is probably the most common treatment although tumor recurrence following surgery is not uncommon (up to 50% in some reports). Cryotherapy (freezing), injection with immunostimulants, topical preparations and laser therapy are all available treatments. These tumors do not metastasize but may get very large at their initail site.
Sarcoids
Squamous cell carcinoma. This tumor is most commonly seen in older horses on non-pigmented (white skin) areas and mucocutaneous junctions such as the vulva and the penis(as seen here and below). They are generally not metastatic but are locally aggressive. Treatment options include surgical excision, radiation, laser therapy and systemic and topical anti- tumor drugs.
Squamous cell on on a vulva
Drainage tract of an ear tooth. An ear tooth (dentigerous cyst) is a congenital abnormality in which the fetal tooth buds, which should migrate to the mouth and form normal teeth, do not migrate appropriately and end up somewhere else (often at the base of the ear or attached to the skull). The body recognizes these abnormal teeth as foreign and tries to reject them by forming a tissue tract to the outside. There may even be "saliva" draining from these tracts. While these ear teeth are not painful and don't seem to bother the horse they will drain until surgically removed.
Large tumor of unknown orign under the tail of an aged Appaloosa
Several small melanomas under the tail. Melanomas are very common in older grey horses (in some reports up to 70% of all grey horses over 12 years of age have some melanomas). They may be found anywhere but by far the most common site is under the tail. Melanomas rarely may be metastatic but they often continue to grow and may eventually obstruct the rectum and anus, as below. Small melanomas may be surgically removed. The anti-ulcer drug, cimetidine, has been commonly used to arrest or reverse tumor growth although there is no good scientifc evidence to support its use as effective.
Melanomas
RAIN ROT
Rain rot (also called dermatophilosis) is caused by the bacteria Dermatophilus congolensis which is a bacteria that lies dormant in the skin. When activated by environmental conditions of moisture, the owner may feel small bumps and scabs along the back and withers (or possibly other areas). Hairs are often stuck together in tufts. The hairs characteristically grow through the scabs, sometimes referred to as the "paint brush" effect. Under the scabs may be pustules, pus, and moisture.
Treatment primarily consists of drying the area because this anaerobic bacterium thrives without oxygen. Removing scabs and clipping the hair away will expose the bacteria to air which helps to resolve the problem. Soaking the hair with antimicrobial shampoo and warm soaks will soften the scabs which may make their removal less painful to the horse. There is no need to prematurely remove the scabs if it is going to cause more irritation.
Antibiotics and anti-inflammatories may be needed for severe cases of rainrot.
Although we have not often seen rainrot's contagious potential in our practice, the possibility exists. Standard disinfection procedures are recommended such as isolating and cleaning grooming tools of affected horses.
Grooming your horse regularly increases the chance of the owner noticing rainrot in its early stages when it is most easitly controlled.
Hives, as seen here and below, usually occur in response to an individuals immune system over-reaction to some type of allergen. These allergens may be ingested, inhaled, injected (ex: spider or other insect bites) or topical contact. The hives (also called wheals) may cause discomfort and itchiness. There may be few or cover the entire body. In severe cases there may be swelling of the face and eyelids and breathing may be compromised due to swelling of the larynx and lung involvement. Worsening signs and any breathing impairment should be considered emergencies and seen quickly. Treatment of hives generally includes systemic antihistamines,steroids and sometimes anti-inflammatories. Response to treatment is usually fairly rapid and dramatic. Most times the inciting cause of the reaction remains unknown.
Hives
Sarcoids (seen here and below) are the most common equine tumors and may occur in a variety of presentations and sites. About 1/3 of all equine tumors may be sarcoids. Their cause is unknown but there may be a viral origin as well as a hereditary component. Surgical excision is probably the most common treatment although tumor recurrence following surgery is not uncommon (up to 50% in some reports). Cryotherapy (freezing), injection with immunostimulants, topical preparations and laser therapy are all available treatments. These tumors do not metastasize but may get very large at their initail site.
Sarcoids
Squamous cell carcinoma. This tumor is most commonly seen in older horses on non-pigmented (white skin) areas and mucocutaneous junctions such as the vulva and the penis(as seen here and below). They are generally not metastatic but are locally aggressive. Treatment options include surgical excision, radiation, laser therapy and systemic and topical anti- tumor drugs.
Squamous cell on on a vulva
Drainage tract of an ear tooth. An ear tooth (dentigerous cyst) is a congenital abnormality in which the fetal tooth buds, which should migrate to the mouth and form normal teeth, do not migrate appropriately and end up somewhere else (often at the base of the ear or attached to the skull). The body recognizes these abnormal teeth as foreign and tries to reject them by forming a tissue tract to the outside. There may even be "saliva" draining from these tracts. While these ear teeth are not painful and don't seem to bother the horse they will drain until surgically removed. 
Large tumor of unknown orign under the tail of an aged Appaloosa
Several small melanomas under the tail. Melanomas are very common in older grey horses (in some reports up to 70% of all grey horses over 12 years of age have some melanomas). They may be found anywhere but by far the most common site is under the tail. Melanomas rarely may be metastatic but they often continue to grow and may eventually obstruct the rectum and anus, as below. Small melanomas may be surgically removed. The anti-ulcer drug, cimetidine, has been commonly used to arrest or reverse tumor growth although there is no good scientifc evidence to support its use as effective.
Melanomas
Rainrot closeup
Rainrot