Respiratory diseases in dogs and cats are one of the most common complicated affections affecting animal health with high morbidity and mortality. The first study aimed to evaluate the clinical, hematological, acute phase proteins (APPs) and radiographic changes during different naturally respiratory affections in dogs and cats. Aimed to isolate and identify the most common associated bacterial agents in pneumonic cases. The affected cases showed inflammatory leukogram, changes in the level of APPs and different radiographic patterns associated with different respiratory affections, The most common isolated pathogens were Klibsiella, E.coli, Pseudomonas and other types. This study revealed that clinical, hematological, biochemical, radiographic examination and bacterial isolation are essential for accurate diagnosis of different respiratory affections in dogs and cats. The second study investigated the role of APPs, Il6 and ultrasonography in the early diagnosis of induced bacterial pneumonia in dogs. The pneumonic dogs showed significant increase in the levels of APPs, Il6 and serum proteins. Ultrasonographic changes in the lung tissues appeared on the 3rd day post induction. This study revealed that ultrasonography, acute phase proteins and Il6 could be used as valuable tools for early prediction and diagnosis of pneumonia in dogs.