Despite its name, ringworm in cats is a fungal infection (not a worm) that causes skin lesions and significant suffering, and is notorious for causing devastating outbreaks in animal shelters.
Ringworm causes uncomfortable skin irritation in affected cats - the lesions are itchy and the required treatment protocol is prolonged and stressful. Lime-sulfur dips, a common treatment, are malodorous and require repeated applications. In shelters, ringworm outbreaks historically triggered mass euthanasia of entire rooms of cats because treatment was considered too resource-intensive. Progressive shelters now manage ringworm through isolation and treatment, but the process requires months of quarantine and regular medical interventions. The zoonotic risk adds urgency but also complexity to management, sometimes resulting in euthanasia of treatable animals.