I could care less about American Hefeweizen. Make a seperate article, this is about Hefe in general. I'd like to add Granville Island Breweries to the list, but lo and behold, it's a list of American brands, and GIB is Canadian. Go figure.
The standard dosage for oral Benadryl is 1 mg per pound of body weight, given 2-3 times a day. Most drug store diphenhydramine tablets are 25 mg, which is the size used for a 25 pound dog. Always double check the dosage before giving an over the counter medication. In addition, many formulations are combined with other medications such as Tylenol so make sure Benadryl tablets contain only diphenhydramine.
Even though it is true benadryl can be given to dogs, you should ask a veterinarian to get the correct dosage. If you are sure your dog has allergies your dog should be seen by a veterinarian to find out the cause of the allergies. You may either need to adjust your dogs diet or environment to correct these allergies.