The larynx is the part of the throat often called the “voice box” in humans. Laryngitis is an inflammation of the larynx. It may result from upper respiratory tract infection or by direct irritation from inhalation of dust, smoke or irritating gas, or foreign objects. It can also be caused by the trauma of a breathing tube placed during surgery or excessive vocalization (barking). Laryngitis may accompany infectious tracheobronchitis and distemper in dogs.
Fluid buildup and swelling of the mucous membranes is often a key part of laryngitis; if severe, the upper airway may be obstructed. Brachycephalic dogs (dogs that have a flattened face with short nasal passages and larynx, such as a Pug), obese dogs, and dogs with paralysis of the larynx, may develop laryngitis through severe panting or respiratory effort during excitement or from being overheated. Swelling of the larynx can also occur due to an allergic reaction.
A cough is often the first noticeable sign of laryngitis. The cough is harsh, dry, and short at first, but becomes soft and moist later and may be very painful. It can be induced by pressure on the larynx, exposure to cold or dusty air, swallowing coarse food or cold water, or attempts to administer medicines. The dog's bark may sound different. Bad breath and difficult, noisy breathing may also be noted, and the animal may stand with its head lowered and mouth open. Swallowing is difficult and painful. Death due to suffocation may occur, especially if the animal is exerted; however, this is rare. When it does occur, it is not the result of laryngitis alone, but rather is due to underlying causes such as paralysis.
Fluid buildup and swelling of the larynx may develop within hours, causing an increased effort to inhale and high-pitched breathing arising from the larynx. The respiratory rate may slow as the animal’s effort to breathe increases. Visible mucous membranes, such as the gums in the mouth, become bluish from lack of oxygen, the pulse rate increases, and body temperature rises. If the swelling obstructs the airways, affected dogs may be unable to cool themselves down in hot weather; a significant rise in temperature is not uncommon. Untreated animals with significant obstruction eventually collapse.
The veterinarian can make a tentative diagnosis based on the clinical signs and physical examination of the dog. A definitive diagnosis requires examination of the larynx with an endoscope; in dogs, anesthesia is usually required during this procedure.
If the larynx is obstructed, an opening will be made in the neck to allow a tracheotomy tube to be placed; this tube enables the animal to breathe while the problem is being corrected. Corticosteroids may be prescribed to reduce swelling and obstruction. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used as an alternative. Diuretic drugs may be used to relieve fluid buildup in the larynx and lungs. Identification and treatment of the primary cause of the laryngitis is essential. Procedures that may be recommended to speed the animal’s recovery and provide comfort include inhalation of humidified air; confinement in a warm, clean environment; feeding of soft or liquid foods; and avoidance of dust. Cough-suppressing medications, pain medications, and antibiotics may also be needed to treat this condition.
Also see professional content regarding laryngitis.