At the clinic I work at, we tell family they can give dogs 1-2mg per lb, so one 25mg tablet, up to 2 tablets, every 8 hours for itching. If it is an allergic reaction, she should be seen by a vet in half a shake to make sure she does not need an injection. But whether shes just itchy, use the Benadryl until you can make an appointment to have her see by a vet.
I would go at once to the Benadryl (be sure to spell it right) website and see what the manufacturer suggests as the right dosage for my dog. I would also weigh my dog again to be sure that I would neither over- nor under-dose my pet. You could also ask your vet if Benadryl would be of any help to your dog and what dose s/he would recommend.
Please remember that antihistamines can effect a dog (or person) to become sleepy, but this effect wears off eventually.
However much the vet prescribed.
The dosage is 1/2 - 2 mg. per pound of body weight every 8 hours,so you could safely give the dog one 25 mg. tablet or medication. This is for Benadryl in the US. If you're in the UK or elsewhere ,Benadryl contains a different ingredient and you cannot give it to dogs.
Answers: My vet once advised me to do one mL of Children's Benedryl per 1 lb of body weight. You can actually be in motion online and find a chart that tells you the specifics.
-and don't pay attention to all these population who say you should rush your dog to the vet anytime he/she sneezes or throws up. You wouldn't rush your baby to the ER everytime it got a runny antenna would you? Benedryl is fine for dogs. You can find more info online.
May I ask for what? It would depend on what you're using it for, so I'll know how much to say..