Give 1mg of Benadryl per pound such that if your dog weighs 30 pounds, you should give it 30 mg of Benadryl. Talk your veterinarian - while antihistamines are generally safe, there are the potential for side effects particularly if your dog has chronic organ failure (renal failure, liver failure, congestive heart failure, etc.).
1 Encephalitis is inflammation of the brain. 2  Meningitis is inflammation of the membranes (called meninges) that surround the brain and spinal cord.  Both encephalitis and meningitis can be caused by bacteria or viruses, and rarely a fungus, or be noninfectious.
Signs and symptoms when the brain is affected - meningitis refers to infection on the outer layer of the brain, while encephalitis refers to infection of brain tissue. The signs and symptoms for both meningitis and encephalitis are similar, and may include: A blotchy rash appears on the skin.