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.
Definition. Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hyper-sensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis.