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, irritating gas, or foreign objects. It can also be caused by trauma, excessive meowing, or a tumor of the larynx. Laryngitis may accompany infectious rhinotracheitis and calicivirus infection in cats. Fluid buildup and swelling (edema) of the mucous membranes is often a key part of laryngitis; if severe, the upper airway may be obstructed. Edema of the larynx can also result from allergic reactions, placement of a breathing tube during anesthesia, or surgery in the area.
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. 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. Vocal changes may be evident. Bad breath and difficult, noisy breathing may be evident, and the cat 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 over-exercised or stressed, or if a mass, lesion, or swelling is severely obstructing the larynx.
The veterinarian can make a tentative diagnosis based on the clinical signs and physical examination of the cat. A definitive diagnosis requires examination of the larynx with an endoscope; in cats, 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. Identification and treatment of the underlying cause is essential. Corticosteroids may be prescribed to reduce swelling caused by inflammation. Diuretics may be used to relieve fluid buildup in the larynx and lungs. Antibiotics may also be necessary. Control of pain with medication, especially in cats, allows the animal to eat and thus speeds recovery. Humidifying the air, feeding soft foods, and confining the cat to a clean area may also help.
Laryngeal paralysis, a disorder of the upper airway, is rare in cats. The condition occurs when the cartilages of the larynx do not open and close normally during respiration.
Signs include a dry cough, voice changes, and noisy breathing that slowly progresses to obvious difficulty in breathing during stress and exertion, and eventually to collapse. Regurgitation and vomiting may occur. The progression of signs usually takes months or even years before respiratory distress is evident. Your veterinarian will generally need to examine your cat's upper airway with an endoscope (laryngoscopy) to confirm the diagnosis. This procedure is done using light anesthesia.
Initially, treatment is directed at relieving the signs of airway obstruction. Tranquilizers and corticosteroids are temporarily effective in mild cases. Severe obstruction may require the placement of a tube into the trachea (tracheotomy). Surgery to correct the problem is often successful.