Auscultation of the lung Auscultation of the lung by the stethoscope. *Compositions of the stethoscope: 1-chest piece 2-Ear piece 3-Rubber tubs *Auscultation area of the lung(triangle of auscultation). 1- Anterior line The area of the thorax extend from Posterior angle of the scapula to olecranon process of the ulna. 2- Dorsal line The situation at the Posterior angle of the scapula to the point of second last intercostal space. 3-Venteral line Starts from olecranon process of the ulna until the distance before the final between the ribs (point of second last intercostal space ) categorically ninth of the middle of the cows rib and rib (eleven or twelfth in the middle of the horses) because the total number of ribs in cows differs in horses, as in cows 13 a pair, while in horses 18 pair) Therefore, this line tends to straight in cows relatively sharp curve in horses.
Notes 1-The chest piece of the stethoscope should be held firmly against the thorax to minimize the crackling sounds caused by friction against hair of the animal s coat. 2- The chest piece should be applied in the intercostal space region to reduce the muffled (silent sound) of the lung, as error of the auscultation. 3-The stethoscope should be applied to each point on the chest wall for the duration of at least one complete respiratory cycle, it is advisable to compare obviously diseases areas with those that are healthy, because this makes it easier to identify any lung abnormality. 4-Comparing corresponding portions of lung on both sides, in the same animals, or in different animals of the same species with similar physical characters, may assist in recognizing relatively minor abnormalities. 5-The respiratory sounds may be masked by the thickness of the chest wall and by presence of subcutaneous oedema or emphysema involving the thoracic region. Intrinsic (Normal) Respiratory sounds The normal respiratory sounds consist of the vesicular sound and the bronchial sound. A- The vesicular respiratory sound. The vesicular murmur resembles the sound produced when the letter (V) is whispered softly in a drawn-out manner. Its presence indicates that the lung contains air and that the alveoli are patent, since it originates from the air vortices that are formed where the terminal bronchioles open into the alveoli. This sound is normally heard throughout the respiratory area, except in the part where it is masked by the bronchial sound. The vesicular murmur is more clearly heard during inspiration, during expiration it may changes its character and resemble the sound of the letter (F). In large animals, when resting the rate of air movement is reduced so that even the inspiratory vesicular sound is submerged.in the dog and cat and in all young animals, the vesicular murmur is readily heard.
*Normal and abnormal breath sounds audible on the lungs (vesicular area). 1- Normal breath sounds Soft blowing sounds, longer and louder on inspiration than on expiration, audible over the trachea and lungs that means normal respiratory tract. 2- Increased audibility of breath sounds Mild to moderate increase in loudness of breath sounds audible on inspiration and expiration over the trachea and lungs e.g any factor that increases respiratory rate or depth of respirations, including fever, excitement, exercise, high environmental temperatures, lung disease. Harsh loud breath sounds are audible over the lungs with any disease resulting in collapse or filling of alveoli a n d leaving bronchial lumina open; pulmonary consolidation and atelectasis. 3-Decreased audibility of breath sounds Decreased audibility of breath sounds on inspiration and/or expiration over the lungs. e.g. Obese animal, pleural effusion, space-occupying mass of lung or pleural cavity, pneumothorax, diaphragmatic hernia, occlusive (lung) airway disease as in bronchial lumen filled with exudate. 4- Crackles Short duration, interrupted, nonmusical breath sounds. Coarse crackles are loud a n d most commonly heard over large airways i n animals with pulmonary disease and may be heard during inspiration and expiration. Fine crackles are of short duration, less intense and higher pitched. e.g Coarse crackles are caused by a i r bubbling through, and causing vibrations in, secretions in large airways. Fine crackles are caused by sudden explosive popping open of a series of airways closed during expiration. May be detected in early or late inspiration. Suggest the presence of secretions and exudate in airways and edematous bronchial mucosa as in exudative bronchopneumonia, tracheobronchitis, aspiration pneumonia and obstructive pulmonary disease. Loud crackles may be audible in animals with interstitial pulmonary emphysema. 5-Wheezes
Continuous musical-type squeaking and whistling sounds audible over the lungs. e.g: Narrowing of large airways; expiratory polyphonic wheezing common in equine reactive airway disease bronchopneumonia, any species; inspiratory monophonic wheezing occurs when upper extrathoracic airways are constricted, such as in laryngeal disease. 6- Pleuritic friction sounds 'Sandpapery' sound; grating; sound close to the surface; on inspiration and expiration; tend to be jerky and not influenced by coughing. E.g: Pleuritis; diminish or disappear with pleural effusion. B- Bronchial respiratory sound This is blowing in character and resembles a long drawn-out guttural (CH) which commences and terminates abruptly.normally it is always audible over the larynx and trachea. * Normal and abnormal breath sounds audible on the larynx and trachea (Bronchial area). 1- Stridor A harsh, high-pitched sound on inspiration audible with or without stethoscope over the larynx and trachea. E.g: Obstruction of upper airways, especially the larynx (due to edema, laryngitis, paralysis of vocal cord); prime example is calf diphtheria or retropharyngeal abscessation in strangles in horses or tracheal collapse in horses. 2- Stertor Snoring sound (low-pitched, coarse and raspy) audible without a stethoscope on inspiration and expiration over the pharyngeal and laryngeal areas. e.g: Partial obstruction of the upper respiratory tract commonly due to abnormalities of soft palate and nasopharynx. 3- Expiratory grunting Loud grunting on expiration, which is usually forced against a closed glottis with sudden release, audible on auscultation of the thorax, over the trachea and often audible without the aid of a stethoscope.
e.g: Severe diffuse pulmonary emphysema; pleuropneumonia and pericarditis; extensive consolidation; in acute pleurisy and peritonitis; a groan indicating pain may occur. 4- Transmitted upper respiratory tract breath sounds Abnormal tracheal breath sounds (crackles and wheezes) audible by auscultation over the extrathoracic trachea during inspiration. E.g: Indicates presence of abnormalities of the upper respiratory tract (larynx, nasopharynx, nasal cavities and upper trachea) resulting in accumulation of respiratory secretions causing constriction of airways. Laryngitis is an excellent example. *Extraneous sounds heard on auscultation of respiratory tract 1- Crepitations in subcutaneous tissues. Loud superficial crackling sounds induced by movement of stethoscope over the skin. e.g: Subcutaneous emphysema from pulmonary emphysema in cattle; trauma to any part of respiratory tract that results in penetration of airway, allowing accumulation of air subcutaneously; gas-forming bacteria in subcutaneous tissues. 2- Peristaltic sounds. Gurgling, grating, rumbling, squishing sounds audible over the lungs. e.g: Gastrointestinal sounds transmitted from the abdomen: ruminal sounds in cattle; stomach and intestinal sounds in horse. Does not indicate diaphragmatic hernia unless other evidence such as an absence of breath sounds is present. Important note -Frictional sound associated with respiratory cycle indicted pleurisy disease. -Frictional sound associated with heart rate indicated pericarditis. Dr. Salah.M.Al-kaabi Preventive & Internal Medicine Vet. Collage