Small Animal Dermatology, 3rd edition

702 DISEASES/DISORDERS

administered with niacinamide 250 mg PO for dogs<10 kg and 500 mg PO for dogs

>10 kg.

 Dapsone:
Dogs only
Added to treatment when prednisolone alone is not sufficient and the primary

cause is unknown

Tapering dosage schedule: 1 mg/kg PO TID for 2 weeks; then 1 mg/kg BID for

2 weeks; then 1 mg/kg q24h for 2 weeks; then 1 mg/kg EOD if sufficient to main-

tain control of symptoms.

 Sulfasalazine 20–40 mg/kg PO TID (maximum of 3 g/day); once remission is achieved,

the dose is tapered by giving 10 mg/kg BID for 3 weeks, then 10 mg/kg q24h.

 Azathioprine: 2 mg/kg or 50 mg/m2 PO q24h until remission; then EOD or twice

weekly; not for use in cats.

 Chlorambucil: 0.1–0.2 mg/kg q24h until remission; then EOD or twice weekly.

 Cyclosporine, microemulsion: 5–10 mg/kg q24h until remission; then EOD or twice

weekly.

Precautions/Interactions

 Dapsone and sulfasalazine: not recommended with preexisting renal disease, hepatic

disease, or blood dyscrasias.

 Sulfasalazine: not recommended with preexisting or borderline keratoconjunctivi-

tis sicca; use with caution in cats; may displace highly protein-bound drugs (e.g.,

methotrexate, warfarin, phenylbutazone, thiazide diuretics, salicylates, probenecid,

and phenytoin); bioavailability decreased by antacids; may decrease bioavailability

of folic acid or digoxin; blood levels may be decreased if concurrently administering

ferrous sulfate or other iron salts.

 Pentoxifylline: may increase prothrombin times; may decrease blood pressure.

COMMENTS

 Depending on medication(s) prescribed: CBC and biochemistry: day 7; every 2–4

weeks until remission; then every 3–6 months when on oral medications; monitor

urinalysis with systemic vasculitis.

 Vasculitis may be difficult to treat and the prognosis is guarded if idiopathic.

 Immunosuppressive therapies should always be reduced to the lowest effective ther-

apeutic dose.