Cats with UAD (<i>p</i> < 0.001), neoplasia (<i>p</i> < 0.001), infectious lower airway or pleural space disease (p < 0.001) and CHF (2.31 g/L, IQR: 0.84-2.57 g/L; <i>p</i> = 0.002) showed significantly higher Hp values compared to healthy cats (1.25 g/L, IQR: 0.81-1.83 g/L) (reference range < 1.9 g/L).<h4>Conclusion</h4>SAA and Hp are not suitable for clearly differentiating between different respiratory conditions in cats. The gene discussed is HP; the disease is neoplasm.