Hyperekplexia is a neurological disorder. The disorder is characterized by prominent startle responses triggered by noise or touch. Symptoms include: prominent startle reflex, puppies who are unable to stand and have a rigid extended posture, tremor (early on), cyanosis while feeding, smaller and lighter puppies, consolidated and hemorrhagic lungs and dilated esophagus. Age of onset from birth, with affected puppies exhibiting clinical signs 5 to 7 days after birth. The symptoms appear to cease when the animals are sleeping or are relaxed. Some of the abnormalities appear more severe in male puppies than in the female.