ADV- Lesson 3- Respiratory Dysfunction


As an animal inhales, fresh air moves through the nose (or mouth), pharynx, and larynx to the trachea. The trachea carries the air to the bronchi, which in turn supply the lungs. Air exchange occurs in the alveoli and the used air follows the opposite path of new air: passing into the bronchi, into the trachea, through the larynx and pharynx, and finally exiting through the nose or mouth. Breathing is relatively simple and is accomplished by the actions of the rib muscles (intercostals) and the movement of a great internal muscle called the diaphragm.

The diaphragm muscle separates the chest, containing the heart and lungs, from the abdomen, which holds the intestines, stomach, liver, bladder, etc. As this muscle moves toward the abdomen, it creates a negative pressure and pulls fresh air and oxygen into the lungs, causing the dog to breathe in (inhale). The chest cavity surrounding the lungs is a vacuum, thus allowing the lungs to inflate easily when the dog inhales. When the muscle moves forward (towards the animal’s head), it causes the lungs to compress and force air out (exhale), thus ridding the body of used air. Foster DVM, Race. “Respiratory System: Anatomy & Function in Dogs.” Pet Education. N.p., n.d. Web. 23 Jan. 2017.

There are many reasons an animal may have difficulty breathing such as shock, allergic reactions, collapsed lung, pneumonia, and choking. When an animal’s breathing is labored, it takes much more effort for them to inhale and exhale. The animal’s breathing patterns may change, and you might notice symptoms such as gasping, wheezing, or struggling to draw in air. Cats that are open-mouth breathing, or animals with blue mucous membranes need to be rushed to a veterinary clinic immediately. An animal that is having difficulty breathing should never be muzzled as it could cause them to go into respiratory arrest and stop breathing.

Respiratory arrest is the cessation of breathing due to the failure of the lungs to function effectively. Apnea is the cessation of breathing. Prolonged apnea refers to an animal who has stopped breathing for a long period of time. If the heart muscle contraction is intact, the condition is known as respiratory arrest. An abrupt stop of pulmonary gas exchange lasting for more than five minutes may damage vital organs, especially the brain, possibly permanently. Lack of oxygen to the brain causes loss of consciousness. Brain injury is likely if respiratory arrest goes untreated for more than three minutes, and death is almost certain if left untreated for more than five minutes.

The gums in the animal’s mouth should be pink as seen in the top picture below. The shade of pink can vary but in general, you are looking for a pink color. This means that there is normal blood flow to the tissues with adequate oxygenation. When the gum color becomes pale (as in the bottom picture), white or blue it usually means there is not enough blood and/or oxygen getting to the body.

Below is a list of respiratory dysfunctions:

  • Agonal Breathing- sometimes referred to as the “Death Rattle” are sounds often produced by an animal who is near death. The rattle noise is caused by secretions accumulating in the throat and upper portions of the chest
  • Orthopnea- breathing with the neck extended and elbows abducted to maximally open the airways
  • Push- pronounced expiratory effort is associated with severe lower airway disease such as feline asthma. Characterized by increased expiratory effort
  • Tachypnea (distressed)- very short, shallow inspiratory periods and evidence of distress
  • Tachypnea (panting)- increased respiratory rate that is not associated with distress
  • Stridor- a high-pitched breath sound resulting from turbulent air flow in the larynx or lower in the bronchial tree. It should not be confused with stertor which is a noise originating in the pharynx. Stridor is a physical sign which is caused by a narrowed or obstructed airway.
  • Stertor- a respiratory sound characterized by heavy snoring or gasping. It is caused by partial obstruction of airway above the level of the larynx and by vibrations of tissue of the naso-pharynx, pharynx or soft palate.
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