Also referred to as Pectus Excavatum (in both humans and animals), this condition is a birth defect that causes animals to be born with deformed chests. This mostly manifests as a flat chest hindering their ability to stand and sometimes the function of organs. While treatable in pets they often die anywhere from two days to four weeks after diagnosis.
Appears?: At birth. It could be visible as the newborn cub art or an altered version with the head down and legs splayed more.
Affects gameplay?: Yes,
Lethal: Yes dies in 1-2 months




Update: This is a disorder related to Riley [piebald] 🍒 (#56451)'s Marfan thread http://www.lioden.com/topic.php?id=304429242985. The concave chest image is the human equivalent of Swimmer syndrome.