this is in general and your vet is the one to decided on the dose
Dosing Information
Medication should never be administered without first consulting your veterinarian.
The usual dose is 2.5 mg per pound ( 2.5 mg/kg) one to two times per day for dogs orally. The dose for cats is 2.5 to 5 mg per pound (5 to 10 mg/kg) every 12 to 24 hours. It is common for fungal infections to require several weeks of treatment.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.
found on here
http://www.petplace.com/drug-library/itraconazole-sporanox/page1.aspxwilson3