In order to verify the radiographic quality, the distribution according to breed, age and sex, and the frequencies of lung radiographic patterns, thoracic films of 79 dogs suspected of lung diseases attended at the Veterinary Teaching Hospital in the Department of Veterinary Medicine, Viçosa Federal University, Brazil, in the year of 2007, were analyzed. The films were analyzed according the technical quality that consists of views produced, position and exposition quality. The lung patterns were classified in interstitial, alveolar, bronchial, vascular or mixed according the anatomic structures affected. Regarding the breed, mongrel dogs (53.44%) and Pinschers (16.43%) were the most frequent breeds suspected of lung diseases. The females (68.35%) as well as dogs over seven years old (68.35%) were the most studied. It were produced 231 films of the 79 dogs, in about 84.81% of the cases the dogs were studied in ventrodorsal and right and left views. The inadequacy of the positions were observed in 65.80% of the films because of rotation of the thorax. Adequate exposition was obtained in 62.22% of the films, but 32.88% were overexposed. In 39.25% of the studies there were no radiographic founds. Mixed pattern was found in 31.65% cases; 17.72% were bronchial pattern; 6.32% were interstitial pattern and 5.06% were alveolar pattern. There was no vascular pattern. The high frequency of mongrel dogs could be related with their high local population and because they are less confined than other dogs of pure breed, being more exposed to climatic changes and contagious diseases. The most frequent isolate lung pattern was bronchial pattern, mainly because calcification of bronchial walls and can be related with aged dogs. The expressive number of females and films with no radiographic founds can be related with the high incidence of lung metastases search in cases of mammary cancer. The results of this study showed that the films had technical fails, mainly with concern the positioning, that must be improved to avoid erroneous interpretation.