Untreated pain in cats can lead to several long-term consequences. Chronic pain can cause behavioral changes, such as increased aggression, anxiety, or depression. Cats may also suffer from reduced mobility, leading to muscle atrophy and decreased quality of life. Persistent pain can negatively impact their appetite, resulting in weight loss and malnutrition. Additionally, untreated pain may cause cats to avoid using the litter box, leading to hygiene issues and potential secondary infections. Over time, chronic pain can significantly diminish a cat's overall health and well-being.