Tylan and penicillin won't treat E. coli, and birds with blackhead almost always get a secondary E. coli infection, so for that you would need something like Baytril.I have safeguard 10% suspension liquid goat dewormer and general cure by API and will be getting antibiotic as I only have tylan 50 and penicillin On hand. I have read several threads on here and have found varying opinions on dosing both metronidizole and safeguard.
The Safeguard dose my vet has me use when treating cecal worms is 50 mg/kg, so that's 1.8 ml for an 8 pound bird.
According to one vet i spoke with, the metronidazole dose should not exceed 60 mg/kg.
60 mg/kg for 8 pounds = 218 mg
50 mg/kg for 8 pounds = 181 mg
The AAAP manual says the metronidazole dose is 30 mg/kg, which is 109 mg for an 8 pound bird.
Your API has 250 mg metronidazole and 75 mg praziquantel.
If you can afford it, please go consult with a vet.