How ‘Lar Par’ is multifaceted but treatable

Everything you need to know about laryngeal paralysis

We have believed for decades that laryngeal paralysis was an isolated disease. Thanks to several recent discoveries, we now know better.

At least in some dog breeds, “lar par” may be only the tip of the iceberg. It can be part of a generalized neuromuscular syndrome called geriatric onset laryngeal paralysis polyneuropathy, or GOLPP.

Let’s dissect this entity.

  • “Geriatric onset” relates to the fact that most affected dogs—mostly Labradors and other large-breed dogs—are over 10 years old.
  • “Laryngeal paralysis” is a progressive disease that leads to suffocation. A severe cyanotic episode can lead to death.
  • “Polyneuropathy” means multiple nerves are affected, most notably in the larynx (recurrent laryngeal nerves), but also in the esophagus and hind legs.

What to Look for

Some signs of GOLPP are well-known: labored breathing, frequent panting, hoarse voice, gagging, cyanosis, throat clearing, hacking, choking, coughing, stridor, dyspnea and hyperthermia. These dogs basically feel, breathe and sound like Darth Vader after he has run a marathon.

However, other symptoms may be overlooked in geriatric dogs that tend to progressively become exercise intolerant. These patients may mistakenly be diagnosed with arthritis, which incidentally is unproven 99 percent of the time. Signs include hind leg weakness, proprioception deficits, hind leg ataxia and muscle atrophy.

In addition, clients may confuse episodes of regurgitation with vomiting or “coughing up.” Such episodes may be blamed on dysphagia when in fact they may be related to megaesophagus.

In 2010, Bryden Stanley,1 a board-certified veterinary surgeon now at Michigan State University, performed esophagrams by giving barium to dogs affected with lar par. Around 70 percent of the patients had esophageal motility dysfunction at the time of diagnosis.

Dysfunction was more prominent in the cervical and cranial thoracic esophagus. Importantly, the number of dogs affected based on the contrast study was much larger than the prediction would have been based on the history.

Dogs with esophageal dysfunction had a higher risk of aspiration pneumonia. In this particular study, all patients showed evidence of polyneuropathy within one year.

Also in 2010, Kelley Thieman,2 a board-certified veterinary surgeon now at Texas A&M University, showed that lar par is part of a generalized polyneuropathy. Electromyography and histopathology revealed abnormalities in muscles of the hind legs.

What Can Be Done

Does all this mean we should stop treating lar par dogs and euthanize them?

Here are excerpts of Dr. Thieman’s conclusions:

“Although dogs diagnosed with [lar par] may eventually develop clinical signs of a generalized polyneuropathy, we do not believe that this possibility should discourage veterinarians from performing corrective surgery for the [lar par] because the polyneuropathy may be slowly progressive.

“Laryngeal paralysis can be a life-threatening condition, so surgery is warranted in dogs with [lar par]; however, owners need to be informed of the potential long-term prognosis and the possibility for development of additional, slowly progressive, neuromuscular abnormalities.”

The most common current treatment for lar par is the tie back, or unilateral arytenoid lateralization. Some complications can arise from having this procedure performed, including aspiration pneumonia, because of the increased area of the rima glottis postoperatively. Aspiration pneumonia happens in about 10 to 20 percent of patients.

Thorough neurologic evaluation was likely only performed when needed, based on a practitioner’s or surgeon’s suspicion. Signs include flaccid paresis, “buckling,” abnormal gait or ataxia.

One hurdle is that most dogs seen by a surgeon for lar par are in such distress that a thorough neurological exam is often difficult at best. Dogs are logically deemed weak because of severe hypoxia, and the compounding effect of neurological abnormalities in the hind legs may go unnoticed.

More Research

More recently, Lauren Bookbinder, a colleague at the Cornell University College of Veterinary Medicine, followed 90 patients diagnosed with idiopathic lar par.3 Of those, 60 percent were Labrador retrievers.

A pre-op intraoral view of a 13-year-old Springer spaniel diagnosed with laryngeal paralysis.

The most common surgical procedure (94 percent) was unilateral arytenoid lateralization. Owners reported an increase in their dogs’ quality of life within two weeks of surgery.

The presence of any neurologic comorbidities was not significantly associated with survival. About half of the dogs available for follow-up had one or more signs of neurologic co-morbidities, including pelvic limb neurologic abnormalities (32 percent) and esophageal abnormalities (10 percent).

Pelvic limb neurologic abnormalities often preceded the diagnosis of lar par. Esophageal abnormalities ranged from 13 months pre-diagnosis to 17 months post-diagnosis. Over half the dogs that had surgical correction and were available for follow-up showed evidence of neurologic comorbitity.

The presence of neurologic comorbidities was associated with an increased overall complication rate and recurring complication rates in dogs that had surgical correction.

Conclusion

The most recent information about lar par is grim, yet it doesn’t mean these patients’ prognosis is hopeless. The tie back remains a highly successful surgery in the vast majority of patients. The procedure allows them to breathe better shortly, if not immediately, after surgery. It’s a beautiful thing. It is truly one of the most rewarding procedures.

What this means is that we need to objectively educate pet owners so they understand what is happening to their dog and what might happen. From experience, I can say that most clients I interact with are more interested in quality of life than record longevity.

Regardless of the complexity of the lar par or GOLPP, suffocation can be relieved by performing a tie back. Ultimately, the proof is in the surgical pudding: Owners of lar par dogs are some of my most thankful clients.

References

  1. BJ Stanley et al. “Esophageal Dysfunction in Dogs With Idiopathic Laryngeal Paralysis: A Controlled Cohort Study.” Vet Surg. 2010, Vol 39, N 2, p. 139–149.
  2. KM Thieman et al.“Histopathological Confirmation of Polyneuropathy in 11 Dogs With Laryngeal Paralysis.” JAAHA 2010, Vol 46, N3, p. 161-167.
  3. LC Bookbinder et al. “Idiopathic Canine Laryngeal Paralysis as One Sign of a Diffuse Polyneuropathy: An Observational Study of 90 Cases (2007-2013).”. Vet Surg. 2016, Vol. 45, N, 2, p. 254-260.

Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. You may visit his website at www.DrPhilZeltzman.com  and follow him at www.facebook.com/DrZeltzman. Columnists’ opinions do not necessarily reflect those of Veterinary Practice News. 

Nikki Schneck, a veterinary technician near Pottsville, Pa., contributed to this article. 

Originally published in the October 2016 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today! 

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