None! If the packaging doesn't have a dose for dogs, then don't give it to them. Claritin is for human use and for human use only. Over the counter drugs are for people. If your pet is having issues, then go to the vet.
Unless instructed to by a vet, you don't.Benedryl would be best to give a dog if he/she has asthma, shortness of breathe and wheezing.One tablespoon (not completely full) would be the correct dosage...