benadryl (cetrizine dihydrochloride)

Question
after umpteen visits to our non helpful expensive vets we noticed our dogs allergies have started to flare up again and i remembered reading about benadryl. my vet will not give me the dosage of what to give him as he wants to get the seeing fee of 40 pounds first which i totally am not happy about. poor dog is itching on his back again and has one itchy eye. he weighs 20kgs and i really need to get the dosage right. please help

Answer
One reliable source says up to 2 mg per pound of body weight.  Many others say 1 mg.  What I see here is 25 mg capsules.  If that is what you have, I would try one every 8 hours.  If that gives little relief, try 2 or even 3.  If you have liquid, I wouldn't go over 88 mg and would start with less.  If your liquid has 12.5 mg in 5 ml, I would start with 10 ml.  

I lack enthusiasm for medicating dogs without the vet's directions, but maybe this is a case for an exception.  Note, I guess dogs get higher doses than people.