I always advise that you should never use medications which are not specifically designed for the specific animal you want to treat – as a rule, you should not use human medications on cats or dogs, or cat medications on dogs, or vice versa. I often respond to questions like this with another question: Would you give your child a medication intended for your dog because you had it in the house and the symptoms appear to be the same?

However, Benadryl is in fact an unusual case, because while it is not approved specifically for use in animals by the FDA (Food and Drug Administration), it can be legally prescribed by veterinarians for use in animals. That said, even in such as case, I recommend only using Benadryl after consultation with your veterinarian, since it can interact with other drugs, and can cause side effects including lethargy and vomiting. In addition, Benadryl should never be used in animals suffering from lung or heart disease, thyroid disease, high blood pressure and prostate enlargement. Your veterinarian will normally prescribe Benadryl at approximately 1mg per pound two or three times per day, which equates to about 65mg per dose for your specific dog.