Laryngeal Paralysis

TL;DR. Laryngeal paralysis is a serious but manageable airway condition in dogs and cats where the vocal folds fail to open during breathing, causing a harsh breathing sound, exercise intolerance, and potential respiratory distress.

The larynx acts as a gatekeeper, opening wide during inhalation and closing during swallowing.

What is it?

Laryngeal paralysis is a dysfunction of the upper airway that primarily affects dogs, though it is also occasionally diagnosed in cats. To understand this condition, it helps to understand the anatomy of your pet's throat. The larynx, often called the voice box, sits at the entrance to the windpipe (trachea). It is made up of several cartilages, including the paired arytenoid cartilages, and the vocal folds.

Normally, when your pet takes a breath, muscles pull these cartilages and vocal folds outward (a process called abduction). This opens the airway wide to let air flow freely into the lungs. When your pet swallows food or water, the larynx closes tightly to prevent anything from entering the lungs.

In a pet with laryngeal paralysis, the nerves that control these opening muscles—specifically the recurrent laryngeal nerves—stop functioning properly. As a result, the cartilages and vocal folds fail to open when your pet inhales. Instead of pulling apart, they remain relaxed and floppy, partially blocking the airway. When your pet tries to breathe in deeply, the rush of air can actually suck the floppy cartilages further inward, severely restricting airflow.

As a leading veterinary critical care reference explains:

"Laryngeal paralysis is the result of recurrent laryngeal nerve dysfunction that impairs arytenoid cartilage abduction during inspiration, leading to respiratory stridor and distress."

In many older dogs, this nerve dysfunction is not an isolated problem. It is often the first noticeable sign of a progressive, body-wide nerve disorder known as Laryngeal Paralysis-Polyneuropathy Complex, or Geriatric Onset Laryngeal Paralysis and Polyneuropathy (GOLPP). Over time, this complex can affect other nerves, leading to hind-limb weakness, muscle loss, and swallowing difficulties.

While this condition is most commonly diagnosed in dogs, cats can also suffer from laryngeal paralysis. Because feline cases are less common, much of the veterinary guidance for cats is extrapolated from canine protocols. Cats present unique diagnostic challenges, as they are masters at hiding respiratory discomfort until they are in severe distress.

Causes & risk factors

Laryngeal paralysis is categorized based on how and when it develops. The most common form is acquired and idiopathic, meaning it develops later in life for unknown reasons. This form is typically seen in middle-aged to older large and giant breed dogs.

Other causes and risk factors include:

• Congenital or hereditary factors: Some dogs are born with the condition or carry a genetic predisposition. In these cases, signs usually appear much earlier in life.
• Trauma: Direct injury to the neck can damage the recurrent laryngeal nerves. This can occur from bite wounds, accidents, or even severe pulling on a collar.
• Tumors: Masses in the neck or chest cavity can press on or invade the recurrent laryngeal nerves, disrupting their function.
• Generalized polyneuropathy: As part of a broader nervous system disorder, nerve degeneration occurs throughout the body.

Heavy panting and exercise intolerance are common early signs of laryngeal dysfunction.

Signs to watch for

Symptoms of laryngeal paralysis often start mild and progress slowly over months or even years. Because the onset is gradual, owners sometimes mistake the early signs for normal aging or slowing down.

Cardinal Signs (Most Common and Distinctive)

• Stridor: A harsh, high-pitched, or raspy breathing sound, especially when inhaling. This is often described as a "roaring" sound.
• Respiratory distress: Labored breathing, rapid breathing, or struggling to catch a breath, particularly during warm weather or exercise.

Common Signs

• Voice change: A change in the sound of your pet's bark or meow. It may sound hoarse, raspy, or lose its volume.
• Exercise intolerance: Tiring quickly during walks or play, or refusing to exercise.

Occasional Signs

• Coughing or gagging: Especially while eating or drinking.
• Regurgitation or vomiting: Bringing up food or fluid shortly after eating.
• Hypersalivation: Excessive drooling due to the effort required to breathe and swallow.
• Cyanosis: Gums or tongue turning blue or purple, indicating a lack of oxygen.
• Collapse: Fainting or falling over due to oxygen deprivation.
• Aspiration pneumonia: A serious lung infection caused by food, water, or saliva accidentally entering the airway.

A laryngoscopy allows your vet to directly observe if the vocal folds fail to open during inhalation.

How vets diagnose it

Your vet will start with a thorough physical examination and laryngeal auscultation. By placing a stethoscope directly over your pet's throat, the vet can listen for the characteristic stridor of upper airway obstruction.

To confirm a diagnosis, your vet must perform a laryngoscopy, which is the gold standard diagnostic test. This procedure requires light anesthesia. Your vet will administer a sedative that keeps your pet relaxed but still breathing on their own. Using a laryngoscope (a tool with a light and a blade to hold the tongue down), the vet will look directly down your pet's throat to observe the vocal folds and arytenoid cartilages. They will watch to see if the cartilages pull open when your pet inhales. If the cartilages remain motionless or move inward during inhalation, laryngeal paralysis is confirmed.

Because other conditions can mimic or complicate laryngeal paralysis, your vet will recommend additional tests:

• Thoracic and cervical radiographs (X-rays): These are essential to rule out other causes of breathing trouble, such as tumors in the chest or neck, and to check for concurrent complications like aspiration pneumonia or megaesophagus (an enlarged, poorly functioning esophagus).
• Thyroid status evaluation: Your vet will run blood tests (such as a T4 or TSH stimulation test) to check for hypothyroidism, as hormone deficiencies can sometimes contribute to nerve and muscle weakness.
• Swallowing studies: If your pet is gagging or regurgitating, a contrast swallowing study can help evaluate their ability to swallow safely.
• Advanced imaging: In some cases, computed tomography (CT) or transnasal flexible endoscopy may be recommended to get a highly detailed view of the airway.
• Laryngeal ultrasound: This non-invasive imaging tool is increasingly used to evaluate cartilage movement without the need for deep sedation.

As a leading veterinary surgery textbook notes:

"Other causes of respiratory distress such as upper airway obstruction caused by intraluminal or extraluminal (thyroid) neoplasia should be considered and ruled out before laryngeal paralysis is considered the primary cause."

Treatment options

Treatment depends on the severity of your pet's symptoms and whether they are experiencing an acute respiratory crisis.

Emergency Stabilization

If your pet is brought to the clinic in severe respiratory distress, they are in a life-threatening crisis. Your vet will immediately place them in an oxygen cage, administer sedatives to calm their anxiety, and use cooling measures if their body temperature has spiked from heavy panting. In extreme cases, the vet may need to place a breathing tube or perform an emergency tracheostomy to bypass the blocked airway.

Medical Management (First-Line and Second-Line)

For mild cases, or for pets that are not good candidates for surgery, medical and lifestyle management may be used:

• Glucocorticoids (Corticosteroids): These first-line medications help reduce swelling and inflammation in the tissues of the throat, which can temporarily improve airflow.
• Methylphenidate (CNS Stimulant): This first-line central nervous system stimulant is sometimes prescribed to help improve nerve transmission and muscle function in the airway.
• Levothyroxine (Thyroid Hormone Replacement): If thyroid testing reveals your pet has hypothyroidism, this second-line hormone replacement therapy will be prescribed to manage the underlying metabolic disease.
• Lifestyle changes: You must strictly avoid exposing your pet to hot, humid weather. Switch from a neck collar to a chest harness to prevent pressure on the throat. Keep your pet at a healthy weight to reduce the workload on their heart and lungs.

Surgical Management

For moderate to severe cases, surgery is the most effective way to restore a reliable airway. The most common procedure is a unilateral arytenoid lateralization, commonly known as a "tie-back" surgery.

During this procedure, the surgeon makes an incision in the side of the neck and places permanent sutures to secure one of the paralyzed arytenoid cartilages in an open position. This permanently widens the airway. Only one side is tied back; tying both sides open would leave the airway completely unprotected, drastically increasing the risk of life-threatening aspiration pneumonia.

Prognosis

The long-term prognosis for laryngeal paralysis is poor without surgical intervention, as the nerve degeneration is progressive and the airway obstruction will continue to worsen.

With proper surgical treatment, such as a unilateral tie-back, the prognosis for improved breathing and quality of life is good. Most dogs experience immediate relief from respiratory distress and can return to moderate activity. However, owners must understand that surgery does not cure the underlying nerve degeneration (especially in cases of GOLPP), and it introduces a lifelong risk of aspiration pneumonia because the airway can no longer close completely during swallowing.

If your pet has concurrent megaesophagus, the prognosis is poor. Megaesophagus makes regurgitation highly likely, and when combined with a permanently open airway from tie-back surgery, the risk of fatal aspiration pneumonia is exceptionally high.

For feline patients, long-term prognosis data is limited compared to dogs. While surgery can be successful in cats, their smaller airways make the procedure technically demanding, and they require highly diligent post-operative monitoring.

Prevention

Because the most common form of laryngeal paralysis is idiopathic or hereditary, there are no proven ways to prevent the disease from developing. However, you can take steps to protect your pet's airway and manage risks:

• Use a harness: Avoid using neck collars, especially if your dog tends to pull on the leash. A harness distributes pressure across the chest and spares the delicate structures of the neck.
• Breeding selection: Breeders should avoid breeding dogs with a known family history of congenital laryngeal paralysis.
• Early screening: If you own a breed predisposed to the hereditary form, discuss early screening options with your veterinarian.

When to call your vet

Laryngeal paralysis can quickly escalate into a life-threatening emergency, particularly during warm weather or times of stress.

You must seek emergency veterinary care immediately if you notice any of the following signs:

• Your pet is struggling to breathe or panting uncontrollably.
• Your pet's gums or tongue appear blue, purple, or pale gray (cyanosis).
• Your pet collapses or faints.
• Your pet is making a loud, high-pitched rasping sound while breathing that does not stop when they rest.
• Your pet shows signs of aspiration pneumonia, such as a soft cough, fever, lethargy, or loss of appetite after a coughing or gagging episode.

For specific breeds

Several breeds have documented predispositions to laryngeal paralysis, with some inheriting specific congenital forms of the disease:

• Labrador Retrievers and Golden Retrievers: These large sporting breeds are the most commonly affected by the acquired, late-onset form of the disease.
• Bouviers des Flandres: A hereditary form of laryngeal paralysis has been reported in this breed, with clinical signs typically appearing very early, between four and six months of age.
• Dalmatians: Young Dalmatians can suffer from an inherited form of the disease that is closely associated with a generalized polyneuropathy.
• Siberian Huskies and Husky Crosses: A hereditary form of the disease has also been documented in these breeds.
• Leonbergers, Rottweilers, Bull Terriers, and Great Pyrenees: These breeds are also suspected to have genetic predispositions, with symptoms often appearing earlier in life than the typical idiopathic cases seen in other large breeds.

Sources

• Current Techniques in Small Animal Surgery, 5th Edition, pages 409–410.
• Small Animal Critical Care Medicine, 2nd Edition, page 119.