Microsporum canis

Itraconazole

Dogs: 5 mg/kg PO once a day for 7 days, stop for 7 days; repeat pattern 3 times^1,2

Cats: 5 mg/kg PO once a day for 7 days, stop for 7 days; repeat pattern 3 times^1,2

Itraconazole, a fungistatic triazole, inhibits the cytochrome P450 enzyme lanosterol 14α-demethylase, which converts lanosterol to ergosterol.³ Decreases in ergosterol affect membrane permeability. Avoid alkalinizing agents (eg, H₂-blockers, antacids).³ Alanine aminotransferase (ALT) and serum alkaline phosphatase (SAP) levels may rise without liver disease signs, though hepatotoxicity is rare.³

In cats, the oral solution is preferred to capsules.⁴ Generic and compounded itraconazole have not been shown to be bioequivalent to Sporanox.⁵ Generic formulations have shown similar pharmacokinetic data; compounded itraconazole has produced low plasma concentrations in dogs and should be avoided.⁵

Terbinafine

Dogs (Oral): 30-35 mg/kg PO once a day^6,7

Cats (Oral): 20 mg/kg PO once a day^6,8

Dogs, Cats (Topical): Apply to affected areas once or twice a day⁹

Formulation: Topical, oral

Terbinafine, an allylamine antifungal agent, is effective and concentrates well in the skin, is well tolerated, and may be used as an alternative when a toxic reaction develops after administration of other antifungal drugs.^8-12 To date, there have been no efficacy comparison studies between itraconazole and terbinafine.

Fluconazole  

Dogs: 5-10 mg/kg PO twice a day^13-15

Cats: 50 mg/cat PO once a day^14,15

Fluconazole is a fungistatic bistriazole that inhibits cytochrome P450-mediated sterol synthesis.¹ Food and gastric pH do not alter bioavailability; it is well tolerated orally.^14,15

Topical Recommendations

(twice a week)¹⁶

• Lime sulfur (1:16)

• Enilconazole (1:100)

• Accelerated hydrogen peroxide rinse (1:20)

• Climbazole mousse

• Ketoconazole (1%-2%) shampoo

• Miconazole (1%-2%) shampoo

H₂ = histamine receptor H₂