This is an acquired disease that occurs in older dogs of the large and giant breeds, particularly Labrador Retrievers, Golden Retrievers, Irish Setters, St. Bernards, and Great Pyrenees. In Siberian Huskies, Bouviers des Flandres, Bull Terriers, and Dalmatians it occurs as a hereditary defect. In these breeds, dogs with this problem should not be bred.
Laryngeal paralysis results from damage to the nerves that control the movement of the larynx. Trauma and age may be factors. Hypothyroidism may also contribute to this problem.
A classic sign of laryngeal paralysis is a characteristic croupy or “roaring” noise heard as the dog inhales. Initially it appears during or after exercise. Later it occurs at rest. Another sign is progressive weakening of the bark, which ends in a croaky whisper. In time the dog develops noisy breathing, labored breathing, reduced exercise tolerance, and fainting spells. Laryngeal edema may develop and further compromise the airway, causing respiratory collapse and even death.
The diagnosis is made by examining the vocal cords with a laryngoscope. Paralyzed vocal cords come together in the middle instead of remaining well apart. This produces a tight air passage through the larynx.
Treatment: A number of surgical procedures have been used to enlarge the airway. The technique used most often involves removing both the vocal cords and their supporting cartilage. This relieves the obstruction, but the dog is unable to bark. Surgery may also predispose the dog to aspiration pneumonia, so usually medical therapy is tried first (keep dog calm and cool, and have sedatives and corticosteroids on hand).
Choke chain injuries, tight slip collars, or any rope around the neck can fracture the hyoid bone and/or cause compression damage to the nerves of the pharynx and larynx. Other causes of trauma to the larynx include bite wounds and sharp foreign objects such as bones and pins that penetrate the larynx. Dogs with laryngeal injuries often breathe normally at rest but show respiratory distress during exertion.
Treatment: Treatment of laryngeal trauma involves confining and resting the dog and administering anti-inflammatory medications. If the larynx is severely traumatized, a tracheostomy (an operation in which an opening is made through the skin into the trachea to establish a new airway) may be required. Choke chain injuries can be prevented by using a buckle collar, head halter, or chest harness.
This is a late stage in airway obstruction. Pressure changes in the upper airway caused by stenotic nares, an elongated soft palate, laryngeal paralysis, or everted laryngeal saccules stretch the ligaments that support the laryngeal cartilages. These cartilages gradually collapse inward and block the airway. At this stage any change in the dog's need for air can cause acute respiratory insufficiency and cardiac arrest.
Treatment: The first step is to surgically correct predisposing factors. If symptoms persist, the dog may benefit from a permanent tracheostomy.
Laryngitis is inflammation and swelling of the vocal cords and surrounding laryngeal mucosa. The signs are hoarseness and the inability to bark. The most common cause of laryngitis is voice strain caused by excessive barking or coughing. In the absence of these, suspect vocal cord paralysis. Laryngitis can accompany tonsillitis, throat infections, kennel cough, or tumors in the throat.
Treatment: Laryngitis due to excessive barking usually responds to removing the stimulus for the barking. When voice strain is due to prolonged coughing, take your dog to the veterinarian to investigate and eliminate the cause of the coughing.
Debarking and Barking Problems
Some dogs simply seem to enjoy barking. But constant shrill barking can lead to problems with neighbors and a dog being dropped off at the local shelter.
Debarking surgery removes some of the vocal chord tissue. This can be done through the mouth or through the throat. Lasers are sometimes used for this surgery. After debarking, dogs can still bark but it is a quieter, hoarse sound. If the dog develops scar tissue, she may recover the ability to bark normally. Too much scar tissue may interfere with breathing. Postoperative care is important, because any swelling in this area could cause acute breathing problems. You may need to search for a veterinarian experienced with this surgery.
Before doing debarking surgery, you should try behavior training and/or eliminate the cause of the excessive barking. Using a citronella or electronic bark collar may also work. These deliver a negative response when your dog barks, either with a spray of citronella or a mild shock.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.