Texas Equine Veterinary Association

www.texasequineva.com • 19 Table 2. Systemic Antibiotherapy for Bacterial Folliculitis in the Horse Drug Dose Ceftiofur 2.2–4.4 mg/kg SC, IM, or IV q 24 h Cephalexin 30 mg/kg PO q 8 h Chloramphenicol 35–50 mg/kg PO q 8 h Enrofloxacin 7.5–10 mg/kg PO q 24 h Horses older than two years old (chondrotoxicity) Reserve when effective based off of antibiogram Can crush small animal tablets or use injectable bovine product PO Withhold alfalfa for 1–2 hours before and 1–2 hours after administration Penicillin 20,000 IU/kg IM q 12h More effective for dermatophilosis when systemic therapy is indicated Trimethoprim- sulfonamide 20–30 mg/kg PO q 12h Author's empiric choice for staphylococcal infection Table 3. Anti-inflammatory Medication for the Horse with Pruritus and/or Urticaria Nonsteroidal anti-inflammatory Dose Chlorpheniramine 0.25–0.5 mg/kg PO q 12 h Doxepin 0.5–0.75 mg/kg PO q 12 h Hydroxyzine 1–2 mg/kg PO q 8-12 h Cetrizine 0.2–0.4mg/kg PO q 12h Pentoxifylline 10–15 mg/kg PO q 12 h Might be a steroid-sparing agent in atopic horses Oclacitinib 0.25mg/kg PO q 24h Steroidal anti-inflammatory Dose Dexamethasone 0.1–0.2 mg/kg PO q 24 h (morning) tapered to 0.01–0.02 mg/kg (or less) PO q 48-72 h Can use injectable dexamethasone PO Not as safe for long-term use Prednisolone 1–2 mg/kg PO q 24 h (morning) tapered to 0.5 mg/kg (or less) PO q 48 h Triamcinolone spray 0.015% Usually 20 to 30ish pump sprays per single application q 12–24 h tapered to the least amount as infrequently as possible Do not be overzealous on the lower limbs as steroids cause cutaneous atrophy prednisolone or dexamethasone is indicated to gain control of itch. Other steroid-sparing treatments, including oral fatty acids and moisturizing/antipruritic shampoos, are prescribed when the horse's history documents recurring and/or chronic pruritic dermatitis and/or urticaria (Table 3). Targeted Control of Long-term Non-insect Allergic Pruritus and/or Urticaria Atopic dermatitis is a clinical diagnosis based on the exclusion of other pruritic flare factors. It can be managed symptomatically with medical treatment (e.g., nonsteroidal anti-inflammatory +/- topical glucocorticoid) when signs are mild and short-lived. However, when symptomatic therapy is not tolerated, signs are severe, and/or disease is recurring (>3–4 months/year), then identifying the allergenic trigger using serum allergy (SAT) or intradermal (IDT) testing is indicated. The purpose of "allergy testing" is to pinpoint candidate allergens to be included in immunotherapy (a.k.a., desensitization or hyposensitization). There is poor correlation between SAT and IDT, because the reactivity measured is applied to different target organs (blood vs. skin). Similarly, lack of correlation between SATs among commercial companies exists because there is no standardization in the field (e.g., source of allergens, epitopes of allergen, and type of assay system); lack of standardization exists for IDT, as well. Fortunately, effective immunotherapy is not based off the test used, but rather correlating the clinical history (e.g., risk of exposure to allergen and seasonality of signs) with test results. Immunotherapy has a reported 60–80% success rate, and in a retrospective study, 84% of owners noted a good response in their allergic horse. Eventually, 59% of horses were managed with sole immunotherapy, while 80% of them required glucocorticoids prior to the use of immunotherapy (Stepnik CT, et al. Vet Dermatol 23: 29–36, 2011). Time to effect may initially be observed in 4-6 months, but appreciable signs of improvement may not be seen for 1 year. Immunotherapy is best viewed as part of the overall "allergy" regimen; it is best used in conjunction symptomatic medical therapy. Currently, there is no information suggesting nonallergen-specific or regional-specific immunotherapy would be effective or ineffective in the horse.

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