Upper respiratory infections (URI) are a leading cause of suffering and euthanasia in shelter cats, and a source of chronic discomfort in household pets.
URI causes genuine suffering: cats with nasal congestion cannot smell food, leading to anorexia that compounds illness. Oral ulcers from calicivirus are painful, making eating and grooming difficult. In shelters, the combination of crowding, stress, and rapid pathogen transmission creates cycles of infection that are difficult to break without isolation capacity. Chronically infected cats living with FHV-1 may experience repeated painful episodes throughout life, often triggered by rehoming stress, veterinary visits, or the addition of new animals. Untreated secondary bacterial infections escalate to pneumonia. These are preventable welfare harms with known interventions.