Guinea pigs are prone to specific medical conditions including dental disease, bladder stones, and vitamin C deficiency that cause chronic suffering when undetected or untreated.
Guinea pig welfare failures are overwhelmingly preventable: scurvy from vitamin C deficiency is entirely owner-prevented through appropriate daily feeding; dental disease is partly diet-related and partly genetic but detectable through veterinary examination; bladder stones are manageable when detected before obstruction. The welfare harm from these conditions — chronic pain, progressive weight loss, inability to eat — is substantial and silent. Annual veterinary checks with examiners experienced in small herbivores catch conditions that owners cannot detect through casual observation.