Startle disease or hyperekplexia is an inherited neurologic disorder affecting Irish Wolfhounds. Affected pups typically present between 5-7 days of age with rigid limbs and tremors when handled. Symptoms stop when puppies are relaxed or sleeping. Affected pups are unable to stand and are smaller than normal littermates. They may stop breathing and turn blue while suckling. Due to poor quality of life, affected pups are often euthanized within the first few months of life.