Chronic proliferative rhinitis (CPR) is a slow and progressive upper respiratory tract disease of sheep with a poor prognosis for affected animals if treatment is not applied in time. It was initially described for the first time in the USA in 1992 (Meehan et al., 1992). It causes a proliferative inflammation of the ventral nasal turbinate with uni or bilateral affection that may totally obstruct the nasal cavity, causing severe inspiratory dyspnea, snoring, and seromucous nasal secretion. When the inflammation progresses, the proliferative tissue appears through the nares. Salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) has been associated with the disease. This microorganism is host-adapted to sheep and is found in the tonsils and nasal secretions of healthy sheep. The etiopathogenesis that causes this inflammatory process to develop in some animals is still unknown. However, in affected animals, the responsible microorganism is located inside the nasal epithelial cells and macrophages, not in the nasal secretions.