Equine respiratory diseases represent a major health challenge for both young foals and adult horses. Therefore, this study aimed to evaluate and compare the respiratory affections in foal and adult horses with upper and lower respiratory diseases. A total number of 150 horses (30 control and 120 diseased) were subjected to clinical, hematological and biochemical examinations. The affected foals and horses were categorized according to clinical and ultrasonographic examination into upper respiratory tract affections (URT) and upper complicated with lower (UCL) respiratory affections. Blood and serum samples were collected from diseased and control foals and adult horses. The results showed significant decrease (P<0.05) in RBCs, HCT, PLT, albumin, A/G, SOD and CAT activity; with significant increase (P<0.05) in WBCs, neutrophil, SAA, Hp, CRP, IL-6, TP, globulin, MDA in URT subgroups. While the UCL subgroups showed significant decrease in RBCs, Hb, HCT, PLT, albumin, A/G, SOD and CAT activity with significant increase (P< 0.05) in WBCs, neutrophil, lymphocytes, SAA, Hp, CRP, IL-6, TP, globulin and MDA. Moreover, there was significant change in WBCs, neutrophil, lymphocytes, HCT, PLT, SAA, Hp, CRP, IL-6, TP, Albumin, Globulin, A/G, SOD, MDA, and CAT between foals and adult horses. Thus, we concluded that timely intervention is crucial to prevent the progression of upper respiratory affections to lower respiratory complications, which can have more severe consequences on the horse's health. Moreover, early management of respiratory tract diseases in horses is recommended through regular monitoring and veterinary care.