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Laryngeal Paralysis

VetBooks.ir ABOUT THE DIAGNOSIS breed and age of the dog, and the history (forming a “presumptive
Laryngeal paralysis is often suspected based on symptoms, the
diagnosis”). The condition is definitively confirmed with a procedure
Laryngeal paralysis is a condition that affects dogs and, rarely, cats.
The larynx is commonly called the voice box because it contains called laryngoscopy. For laryngoscopy, a dog is lightly sedated.
the vocal cords. It is situated in the neck near the beginning of the Either through direct visualization or using an endoscope (small
windpipe (trachea), which carries air to and from the lungs during tube that has a camera attached to its end), the movement of
breathing. As air moves over the vocal cords, sound or voice is the cartilages is observed as the dog breathes; limited movement
produced. The opening of the larynx consists, in part, of two “gates.” indicates laryngeal paralysis. Ultrasound examination of the larynx
These gates are cartilage plates that are told by nerves when to or fluoroscopic moving picture X-rays are novel approaches that
open or close. When a dog swallows, the cartilages close tightly can also help to diagnose this disease.
to prevent food and water from entering the lungs. On the other Your veterinarian may take x-rays of your dog’s neck and chest
hand, these cartilage gates should open fully to allow an animal to to help determine if pneumonia or any other respiratory problems
breathe in (inhale). They open to a lesser degree when breathing may be occurring simultaneously. Blood samples may be taken at
out air (exhale). several points in time to help to determine if the thyroid and adrenal
In a dog with laryngeal paralysis, one or both of the cartilages (the glands are functioning properly.
“gates”) responsible for opening and closing the larynx are unable
to open properly. Early on in the process when there is still some LIVING WITH THE DIAGNOSIS
movement, the only change may be noisy breathing or a change Laryngeal paralysis is a progressively worsening, potentially serious
in the bark or meow. As paralysis worsens, breathing can become condition. When a dog suffers a sudden breathing crisis as a result
labored with little air able to enter the lungs. This will cause the dog of this condition, it is an emergency. In such situations of respiratory
to tire easily on exercise, make loud noises that sound like wheezes distress, try to keep the dog as calm as possible. If the dog has
when breathing in (called stridor), or even develop distress trying become severely overheated, cool damp cloths can be placed
to breath. In the worst-case scenario, this can lead to collapse on the footpads and belly. If outside, an overheated dog can be
and death. Often these symptoms are worse after exercise or in hosed down with cool water. Do not place an overheated dog
hot weather. This problem most commonly occurs in large breed, in an ice bath because this causes the body temperature to fall
adult dogs, with the age of first symptoms typically being between too quickly, which can cause other serious problems. If there is
6 and 12 years of age. While any dog breed (or even cat) can be labored breathing beyond normal panting, take your dog to your
affected, the Labrador retriever is the single most often affected veterinarian or the closest emergency clinic immediately, before a
breed. Rarely, in some breeds such as the Bouvier des Flandres, life-threatening crisis develops.
the condition can be present at birth (congenital). Once the diagnosis of laryngeal paralysis is confirmed, it is
The cause of laryngeal paralysis is usually unknown (idiopathic). important to keep the dog out of situations that cause excite-
Other diseases have been linked to this condition, although a true ment. Do not allow the dog to become overheated; dogs regulate
cause-and-effect relationship has not yet been proven. These their temperature through breathing, so laryngeal paralysis makes
diseases include hypothyroidism (decreased thyroid gland activity) them very prone to overheating or heat stroke. For dogs with
and hyperadrenocorticism (Cushing’s disease, which is an increased moderate or severe laryngeal paralysis, a surgical procedure can
amount of certain hormones responsible for metabolism). A rare be performed that props the paralyzed larynx in a partially open
cause of laryngeal paralysis is the presence of a tumor near the position and prevents episodes of respiratory distress from recurring.
nerve(s) that control(s) the movement of the cartilages or nerve Unfortunately, the surgery doesn’t “fix” the larynx, it just ties open
injury from trauma. Very often, dogs with laryngeal paralysis have one of the closed gates.
or will develop dysfunction in other nerves in the body (called
polyneuropathy). Nerve dysfunction elsewhere in the body can TREATMENT
cause other signs, such as weakness in the rear legs. Sudden breathing difficulties caused by laryngeal paralysis require
Outward symptoms of laryngeal paralysis include the development immediate intervention. Ironically, the harder the pet works to
of breathing problems when a dog exercises, becomes excited, or breathe, the less air will flow through the larynx. For this reason,
if the dog becomes overheated. A characteristic wheezing sound the veterinarian may give a sedative to help the dog calm down
during exertion is very suggestive of laryngeal paralysis, and you may and not try so hard to work at breathing. An antiinflammatory (e.g.,
help your veterinarian and your dog enormously by videorecording a corticosteroid injection) can be given to help control swelling in
this (including audio)—or conversely, capturing a video recording of the throat. In some cases, a veterinarian will need to temporarily
normal breathing sounds during exercise, making laryngeal paralysis insert a tube into the windpipe, through which the dog can breathe
much less likely—for your next veterinary visit; be sure to include (tracheostomy) and prevent suffocation.
audio so the veterinarian can hear the sound of breathing, but avoid Long-term treatment involves a surgical procedure. In this pro-
overexerting your dog beyond his/her usual routine, as excessive cedure, part of the laryngeal cartilage that does not open properly
activity could be dangerous. Dogs with laryngeal paralysis often will is sutured into a permanently open position (tieback procedure).
gag or cough when eating or drinking. Because movements of the This surgery is often performed by a veterinary surgical specialist.
larynx are uncoordinated in dogs with laryngeal paralysis, food can Many factors must be considered before a dog can undergo this
slip through to the lungs and cause pneumonia (aspiration). With surgery; not all dogs with laryngeal paralysis are candidates for
laryngeal paralysis, a dog’s voice can change, and a change in this surgery. Your veterinarian can discuss this option with you.
the sound of the bark is often one of the early markers of laryngeal Importantly, this surgical procedure increases the risk of a dog
paralysis. accidentally inhaling food into the trachea and lungs, a process

From Cohn and Côté: Clinical Veterinary Advisor, 4th edition. Copyright © 2020 by Elsevier Inc. All rights reserved.