Equine Dermatology

Sabrina Jacobs, DVMPerformance Equine Vets

Aiken, SC

Introduction:

■ Bacterial Folliculitis■ Dermatophytosis (Ringworm)■ Dermatophilosis (Rain Rot)■ Urticaria (Hives)■ Culicoides Gnat Hypersensitivity (Sweet Itch)■ Pemphigus Foliaceous■ Grease Heel Syndrome (Scratches)■ Papillomans■ Sarcoids

Topics to be discussed:

■ Etiology■ Pathogenesis■ Clinical signs■ Diagnosis ■ Treatment

Bacterial Folliculitis

■ Staphylococcus spp.■ Opportunistic Infection■ Crusts, papules, pustules typically in a

circular pattern■ Pruritic (Itchy)■ Methicillin-resistant staph MRSA■ Diagnosis by Culture

Bacterial Folliculitis

Bacterial Folliculitis

Bacterial Folliculitis Treatment

■ Remove Crusts■ Bathe with Chlorhexidine or Malaseb Shampoo

(let sit for 15 minutes)■ Topical Triple Antibiotic or Silver Sulfadiazene

Cream■ Systemic Antibiotics: SMZ (Baytril if resistant)

may be necessary■ Keep dry

Dermatophytosis (Ringworm)

■ Trichophyton equinum and T mentagrophytes are the most often fungal organisms identified

■ Warm/Humid Climates■ Lesions on the limbs and pressure areas■ Scaling, Crusts, Alopecia (sharply demarcated)■ Zoonotic AND Contagious between horses■ Fomites- Tack, Bridles, Halters, Saddle Blankets■ Diagnosis: Special DTM Media (1-4 weeks)

Dermatophytosis

Dermatophytosis

Dermatophytosis Treatment

■ Scabs and crusts should be removed, lesions cleaned well, clip hair (clean clippers to eliminate spread to other horses)

■ Miconazole Shampoo (Malaseb)■ Ketaconazole Shampoo■ Ketaconazole Cream■ Silver Sulfa Diazene Cream■ Systemic Anti-fungals (Griseofulvin) in select cases

Dermatophilosis (Rain Rot)

■ Actinomycete (Bacteria)■ Carrier animal, moist environment, abrasions■ Chronically affected animals are primary source

of infection, moisture releases zoospores■ Mechanical transmission by flies or fomites■ Fall/Winter most common■ Dorsal surfaces affected■ Diagnosis: Cytology, Culture, Biopsy

Dematophilosis

Dermatophilosis

Dermatophilosis Treatment

■ Remove crusts, can be very painful, sedation may be required

■ Clip margins, most important■ Clean skin with chlorhexidine or betadine scrub■ Malaseb shampoo, Lime Sulfur Shampoo■ Systemic Antibiotics SMZ or Penicillin■ Immune Boosters (ie Eqstim)■ Use dilute Clorox for equiment or tack NOT THE

HORSE!■ SSD can be used for deep lesions

Urticaria (Hives)

■ Immune mediated reaction■ Food, inhaled, contact (insect, shavings, blanket),

injection (insect, vaccines, drugs),■ Pitting edema, pruritis (small or large)■ Symptoms not a disease■ List of possible causes, can make the diagnosis

seem ominous■ Serological testing vs Intradermal testing

Urticaria

Urticaria Treatment

■ Depends on case:■ +/- glucocorticoids■ +/- bathing with oatmeal shampoo if

contact■ +/- antihistamines■ +/- NSAIDS (Banamine)■ Can be life threatening

Culicoides Gnat Hypersensitivity

■ Puritis! Puritis! Puritis!■ Breed predisposition: Welsh Ponies, Arabians,

Connemaras, Icelandic Horses, QH, Shires, Andalusian, Friesian

■ Seasonal (June- September)■ Mane, Tail, Ventrum, Face, Legs■ Alopecia, excoriations, open sores, bleeding■ Rule out other diseases (cytology, culture, ect)■ Allergy testing to Prove

Culicoides Gnat Hypersensitivity

Culicoides Gnat Treatment

■ Fatty Acid Supplement (6-8 wks for effect)■ ****Boett Blanket: www.boettusa.com■ Antihistamines■ Allergy Shots■ Garlic?■ Glucocorticoids (Prednisolone)■ Topicals: Oatmeal Shampoo, Aloe, Steroids, Scratches

Meds, Swat ■ Fans, stall before dusk to mid-morning■

Culicoides Gnat Hypersensitivity

Pemphigus Foliaceous■ Autoimmune skin disease■ Autoantibodies are directed against surface proteins of

keratinocytes which results in acantholysis (loss of adhesion)■ Waxing and waning vesiculopustular disorder■ Vesicles, pustules, crusts, alopecia, epidermal collarettes, scaling■ Lesions can begin on head or legs and spread to rest of body■ Depression, poor appetite, weight loss, fever■ Diagnosis: Cytologies, biopsy, Cultures, Skin scrapings■ Treatment: Glucocorticoids■ Prognosis: Poor

■

Pemphigus folliaceous

Grease Heel Syndrome (Scratches)

■ Numerous causes for grease heel exist.■ Infections, allergies, photosensitization,

cannon keratosis, parasitic and idiopathic causes have all been associated with grease heel.

■ Pathogenesis for the idiopathic form is thought to be due to an irritant, moisture or poor hygiene.

Scratches Syndrome■ Dermatitis of the lower legs■ Pruritus and pain may be

present.■ Swelling and erythema that

starts on the posterior aspect of the pastern and spreads dorsally and anteriorly.

■ Lesions progress to include crusting, exudation, lichenification and ulceration.

Scratches Symptoms

■ If lesions are allowed to progress then exuberant granulation and keloids develop (“grapes”).

■ Lesions tend to be more sever in the hind limbs.

■ Some horses only have 1 limb affected.

Scratches Treatment

■ Affected areas should be clipped■ Cleaned twice daily■ Topical medications and steroid

preparations may be beneficial■ Scratches Meds twice daily application■ Most important to keep DRY

Papillomas

■ Papillomas are caused by papovaviruses (DNA). Two different viruses are thought to be involved.

■ The presence of the virus in the skin stimulates epithelial proliferation.

■ Verrucous warts usually occur in young animals; aural plaques are usually seen in older animals.

Papillomas

■ Lesions consist of squamous verrucous papillomas.

■ These lesions are located on the muzzle, genitalia and/or lower limbs.

■ Verrucous warts usually spontaneously regress within 6 months.

Papillomas (Aural Plaques)■ Skin lesions consist of

depigmented papules or plaques which occur in the inner surface of the pinna.

■ The lesions progress to a larger coalescing plaques with adherent scale.

■ No reliable treatment■ Aural plaques do not

spontaneously resolve.■ Application of insecticides to

the area help to prevent irritation of the plaques by feeding flies.

Sarcoids

■ Most common causes of locally aggressive, non-metastatic fibroblastic nodular neoplastic lesions in horses, and they account for 35–90% of dermatological neoplasms

■ Bovine papillomavirus (BPV)■ Areas of trauma or injury or irritation■ Diagnosis: Visual or Biopsy■ Surgical excision alone results in 50% recurrence

Sarcoids

Sarcoids Treatment

■ Chemotherapy injections■ Chemotherapy beads■ Cryotherapy■ Laser removal■ Xxterra (Herbal)■ Aldara (Immune Modifier)■ Acyclovir (Antiviral)

Questions?