Laryngeal Paralysis in Dogs

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Laryngeal Paralysis in Dogs | Jean Dodds, DVM

Wheezing? Raspy? Rattling noise? Panting more heavily than usual? Loud panting? Pitch or volume changes to your dog’s bark? Oftentimes, we attribute these stridor and other sounds to old age, allergies, or heat. It could be one of these conditions. The problem is we may become accustomed to the slow progression of changes that actually reflect laryngeal paralysis, which can become life-threatening.

Laryngeal paralysis is a neuropathy (nerve damage or pathology), which is the usually due to degeneration of the junction between the nerves and muscles. In this instance, the larynx (aka voice box) is affected. Not only does the larynx help with vocalization, but it also protects the trachea from food aspiration and assists with breathing. As the nerve-muscle connection deteriorates, the muscles are not receiving messages from the nerves to contract upon inhalation and relax during exhalation. The muscles become progressively paralyzed. Think of a paraplegic: damage occurs to the spinal cord nerves so the muscles cannot receive messages to move. Now, this is not to mislead you; trauma can cause laryngeal paralysis but other conditions can do so as well.

Laryngeal paralysis is either congenital (hereditary) or acquired. The hereditary form presents early in life, generally before two years of age. 

We know that certain Bouvier des Flandres dogs have have an autosomal dominant trait that causes laryngeal paralysis. 

Increased incidence in Dalmatians, Siberian Huskies, Bull Terriers and Rottweilers has also been reported, but the inherited gene(s) responsible has not yet been identified. 

Typically, these companion dogs have loss of full body coordination (ataxia) and should not be used for breeding. It would be difficult for affected females to survive the stress of whelping, plus the risk of passing along the disorder to some of her offspring.

Acquired Laryngeal Paralysis

Any dog can develop the acquired form, but it mostly affects males of larger breeds such as Newfoundlands, Labrador Retrievers, Golden Retrievers, Irish Setters and St. Bernards.

Acquired laryngeal paralysis is typically a later-stage, secondary condition from a primary disease such as hypothyroidism, cancer, vagus nerve anomaly, hypoadrenocorticism (Addison’s Disease), or other immune-mediated diseases. Idiopathic (of unknown cause) laryngeal paralysis can be diagnosed as well, but that usually means that the veterinarian has not identified the primary condition or it has not yet shown up clinically.  

The late stage signs of acquired laryngeal paralysis will usually be the subtle changes in breathing noted previously that could take months or more to develop. Pet caregivers should be attuned to other changes before dyspnea (labored breathing) or severe respiratory distress sets in – such as a dog gagging or choking during eating or drinking. Other early symptoms of laryngeal paralysis include diminishing endurance and exercise intolerance, which are also side effects of hypothyroidism.

While many veterinarians and researchers recognize that hypothyroidism is often present with laryngeal paralysis, they may believe that the correlation between the two is inconsistent. However, we know that the thyroid gland plays a part in nerve health, as it does for all metabolic and tissue pathways. So, “inconsistency” may mean two things:

1. If hypothyroidism is diagnosed at the same time as laryngeal paralysis, other medicinal or surgical interventions may be used concurrently with thyroid medication. So, we may not know how much the thyroid medication alone could be contributing to prevent or reverse further nerve damage.

2. Another scenario pertains if hypothyroidism is diagnosed but laryngeal paralysis is not, as studies have not been conducted about how much thyroid medication is protecting against or minimizing further deterioration of the nerves.  

Diagnosing Laryngeal Paralysis

Even though the late stage signs are evident upon presentation, the early signs may suggest another condition such as megaesophagus. So, veterinarians need to figure out which condition it is because the treatment protocols and approaches are quite different. The available diagnostic tools include x-ray, bronchoscopy (endoscopy), laryngoscopy, and fluoroscopy. Fluoroscopy is a continuous moving x-ray using a fluoroscope that presents a movie of the air moving in and out of the lungs. The fluoroscopy technology is expensive and new so you may need to go to a veterinary school or specialist clinic to have it done.

Treating Laryngeal Paralysis

Medications are available to manage laryngeal paralysis. If the condition is severe, classified as idiopathic, or medications are ineffective, a surgical procedure called a “tieback” (arytenoid lateralization) is an option. However, postsurgical complications such as aspiration of fluids into the lungs could arise.

Other practical management techniques for all stages of laryngeal paralysis include:

  • Using harnesses and avoiding collars
  • Maintaining a healthy weight
  • Avoiding exercise in warm and humid conditions

W. Jean Dodds, DVM
Hemopet / NutriScan
11561 Salinaz Avenue
Garden Grove, CA 92843

References

Monnet, Eric, DVM. “Managing Laryngeal Paralysis (Proceedings).” DVM360, 01 Aug. 2011. Web. 25 Sept. 2016. http://veterinarycalendar.dvm360.com/managing-laryngeal-paralysis-proceedings.

Monnet, Eric, DVM. “Laryngeal Paralysis (Proceedings).” DVM360, 01 Oct. 2011. Web. 25 Sept. 2016. http://veterinarycalendar.dvm360.com/laryngeal-paralysis-proceedings-2.

Waldron, Don R., DVM. “Laryngeal Paralysis in Dogs and Cats (Proceedings).” DVM360, 01 Nov. 2009. Web. 25 Sept. 2016. http://veterinarycalendar.dvm360.com/laryngeal-paralysis-dogs-and-cats-proceedings-0

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