Circadian rhythms underlie healthy physiology and are integral to recovery from disease as circadian disruption impairs healing and results in worse long-term outcomes. The field of circadian medicine applies concepts of circadian biology to clinical practice to improve the health and recovery of patients. Recent research has highlighted several applications of circadian medicine to human health. However, circadian medicine also has several applications to animal health. Modern hospital settings result in abnormal patient exposure to light and sound at night, disturbing circadian rhythms, particularly in the intensive care unit. This is also true of veterinary clinical care settings. This thesis investigates the application of circadian medicine in companion and agricultural animals, culminating in the field of circadian veterinary medicine. Additionally, this thesis investigates the potential impact of circadian misalignment on veterinary patients and possible strategies to ameliorate this impact. We show that inappropriate exposure to light at night in veterinary intensive care settings disrupts animal circadian rhythms thereby exacerbating disease and impairing recovery. The use of red light at night presents a possible solution, as demonstrated in our findings that patient rhythms were not impaired under this protocol.