A cat's extremely fast respiratory rate may be caused by too hot weather, heat stroke, stress reaction, nervousness, fear, heart disease, respiratory disease, or lung disease; if it is due to the weather, you can help the cat relieve the heat. Cool down to avoid heat stroke in cats; if it is caused by emotions, cats can generally relieve it on their own; if it is not caused by weather or emotions, and the cat suffers from this condition frequently, it is best to send it to a pet hospital for examination.