Amantadine Hydrochloride is a medicine used to treat pain in dogs and cats caused by arthritis, cancer, chronic conditions, neuropathy, de-claw surgery, etc. It works best when used with other pain relievers. In addition, Amantadine can also be prescribed as an antiviral agent. Amantadine is available in both capsules and tablets and is sold per capsule/tablet. Amantadine requires a prescription from your veterinarian.