Bartonella henselae causes cat scratch disease in humans but can also cause chronic illness in cats themselves, with implications for both feline welfare and the human-cat relationship.
Most cats infected with Bartonella show no clinical signs, but some develop genuine illness including prolonged fever, lymphadenopathy, and eye inflammation that causes discomfort. The welfare impact on individual cats varies widely. Of greater welfare concern is the human response to diagnosis — some owners choose euthanasia of asymptomatic cats after a human household member contracts cat scratch disease, despite the fact that rigorous flea control eliminates most transmission risk. Educating owners about the modest and manageable risk of Bartonella, and the effectiveness of flea prevention, preserves both cat welfare and the human-animal bond by preventing unnecessary relinquishment or euthanasia of healthy animals.