Get Your Dog Care Questions Answered by Experts
I would use benadryl instead of claritin. It is safer for dogs. My vet recommends 1 mg per lb of body weight given every 8-12 hours as needed.
If you need something to use long term, you should talk with your vet about a prescription anti-histamine.
Let me know if you still have questions.
Unless the dog has been given a large dose, it should not knock him out. Keep in mind that you are dosing it based on his weight and most adult medications are based on age, so the dose for pets is more accurate.
Chlortrimeton can also be used effectively but your vet will have to give you the dosage on that one.
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