medication -- n. a substance used in treating disease or relieving pain

lungs – n. organs that people and animals use to breathe air

resistant – adj. not affected or harmed by something

lethargic – adj. feeling a lack of energy or a lack of interest in doing things

veterinarian – n. a person who is trained to give medical care and treatment to animals

tremendously – adv. very large or great

optimistic – adj. expecting good things to happen

chronic – adj. continuing or occurring again and again for a long time

expectancy – n. a feeling that something is going to happen

species – n. a group of animals or plants that are similar and can produce young animals or plants

sanctuary – n. a place where animals can be protected in a natural setting