Clinically, domestic pets do not necessarily cause pulmonary nodules. There are many causes of pulmonary nodules, such as pathogenic infections, smoking, environmental pollution, immune factors, etc., and Mycobacterium tuberculosis is the more common clinical cause. There is a theory that people allergic to pet hair can cause lung nodules due to repeated coughing, but there is no large amount of relevant clinical data to prove it. In other words, pulmonary nodules may be caused by smoking, pathogen infection, environmental pollution or autoimmune abnormalities, and are not necessarily related to domestic pets. For the time being, the majority of patients with lung nodules are asymptomatic and are found during physical examinations. Smaller lung nodules are mostly benign, and some of them are tumors. It is recommended to go to the hospital for standardized diagnosis and treatment in time.