These microscopic mites burrow under the skin and cause severe pain. You may notice scratching, biting, hair loss, and in serious cases, seizures. Severe infestations can be life threatening. If you suspect one of your guinea pigs have mange mites, treat them all (they can be carriers while not showing signs) as soon as possible. Ivermectin is the treatment of choice. Multiple doses are necessary because ivermectin does not kill the eggs. Read more about ivermectin.