Later correction:
 
"Long-acting" Penicillin (ie. Procaine Penicillin) is SAFE for chickens, unless perhaps a particular chicken has an allergy to it. (I imagine you need to be aware of egg & meat withdrawal as they might relate to people, though.)
Please forgive my posting incorrect info earlier.
	
		
			
		
		
	
				
			"Long-acting" Penicillin (ie. Procaine Penicillin) is SAFE for chickens, unless perhaps a particular chicken has an allergy to it. (I imagine you need to be aware of egg & meat withdrawal as they might relate to people, though.)
Please forgive my posting incorrect info earlier.
	