The ribs in the dog (and cat) are arranged in such a manner that most movement, and the inspiratory effect of that movement, is related to cranial displacement of the ribs during inspiration (Figure 1). Breathing takes place around this equilibrium, with most of the energy of breathing expended to increase the thoracic volume above the equilibrium point during inspiration. Between breaths, these opposing forces yield a pleural pressure of -5 cm H 2O at the 8th-9th interspace in an average size dog. Because there is an airtight seal within the pleural space and the lungs are coupled to the chest wall with a viscous fluid, the tendency of the lungs to collapse is countered by the tendency of the ribs to spring out.
The lung volume in a normal animal is maintained by support from the thoracic wall.
The collapse won't stop until the lung volume is quite a bit smaller than the normal functional residual capacity (FRC) in the intact animal. If the chest is opened to the atmosphere the lungs collapse until small airway occlusion prevents further loss of gas. Lungs are a viscoelastic tissue suspended within the pleural cavity. This lecture will present some basic elements of the bellows part of this system, providing a basis for evaluation of respiratory patterns in the dog. However, instruction in these techniques requires tuition from a health profession with expertise in breathing disorders and home training.Īt present, little research is available to support breathing re-training for people with bronchiectasis but clinically it is recognised as an important addition to a comprehensive management plan for this group of patients.Respiration requires an integrated system of control (CNS), movement of a bellows (ribs and associated muscle) to draw air into the lungs, exchange of gas within the lung, and a feedback system (chemoreceptors, stretch receptors) to close the loop. Efficient breathing patterns which enhance the use of the diaphragm and external intercostal muscles improve quality of life for people with chronic respiratory conditions (Burgess et al 2011). This disordered breathing pattern inhibits airway clearance therapies, and increase the risk of lower respiratory exacerbations.Ī poor breathing pattern generally results from repetition and muscle memory and is a common scenario for people with chronic respiratory conditions. This may be due to a chronic cough, which engages the accessory muscles of respiration and reinforces a poor breathing pattern, or to patients adapting their breathing pattern so that the cycle of inspiration and expiration occurs above their sputum to prevent a cough. An upper chest breathing pattern is a common presentation for patients with excess sputum. These mechanisms are dependent on airflow from an efficient breathing pattern. In people with COPD or a suppurative lung disease, the removal of sputum is reliant on annular and slug flow along the bronchi, assisted by functioning cilia. In asthma, it is well demonstrated that hyperventilation is a trigger for some individuals (Hough 2001). These breathing disorders can result from a chronic respiratory condition, such as asthma, chronic obstructive pulmonary disease (COPD), or a suppurative lung disease. Two common breathing pattern disorders are hyperventilation and upper chest breathing, both of which utilise the accessory muscles of respiration. However, breathing dysfunction, characterised by excessive recruitment of accessory muscles of respiration at rest, may increase oxygen consumption by up to thirty percent (Berne & Levy 1998). A good breathing pattern, which uses the diaphragm and external intercostal muscles to breathe in and elastic recoil to breathe out, enables the body to function efficiently with minimal oxygen consumption.