Malignant Ovine Theileriosis caused by T. lestoquardi is the lethal disease that causes high morbidity and mortality worldwide. The disease is diagnosed by clinical signs and pathological findings together with morphological demonstration of the parasite in lymph node biopsy and blood smears. To date, little is known about the pathogenesis of T. lestoquardi infection and the different tissue and organs alterations. T. lestoquardi infections are accompanied by severe pulmonary involvements. Serious tissue destructions and pulmonary oedema, suggest that emphysema and interstitial pneumonia may lead to respiratory failure and could provides direct evidence for death. I am proposing that lungs appear to be the preferred site for T. lestoquardi invasion. Consequently, I could speculate that, T. lestoquardi is a respiratory disease. My findings may assist in filling the gaps in our knowledge about the disease pathogenesis and could have application significance in diagnosis and developing strategies for therapeutic attack on the parasite. These results could contribute to raise awareness among veterinary authorities regarding the pathognomonic lesion for early and differential diagnosis.