Laryngeal Disease in Dogs and Cats: An Update

Question 1

What are the possible causes of aquired laryngeal paralysis in dog? And what is the most common cause?

Answer 1

Congenital:
- Genetic trait
- Laryngeal paralysis: polyneuropathy complex

Accidental trauma
- Cervical penetrating wounds
- Strangulating trauma
- Iatrogenic surgical trauma
- Cranial thoracic surgery
- Correction of patent ductus arteriosus/vascular ring anomaly
Thyroidectomy/parathyroidectomy
- Tracheal surgery
- Ventral slot surgery

Cervical/intrathoracic neoplasia
- Lymphoma
- Thymoma
- Thyroid carcinoma/ ectopic thyroid carcinoma

Neuromuscular disease
- Geriatric-onset laryngeal paralysis polyneuropathy syndrome
- Endocrinopathy (hypothyroidism, hypoadrenocorticism)
- Immune mediated
- Infectious
- Myasthenia gravis
- Polymyopathy
- Systemic lupus erythematosus
- Toxins (lead, organophosphates)

Most common: progressive generalized neuropathy

Question 2

What dogs (breed and age ) are mostly affected?

Answer 2

> 9 years, large-breed and giant-breed dogs.
Congenital form: Bouvier des Flandres, Siberian huskies, bull terriers, and whitecoated German shepherd dogs.
Hereditary predisposition: Siberian husky dogs, Alaskan malamutes, and crosses of those
two breeds
For the more frequently encountered acquired laryngeal paralysis, the Labrador retriever is the most common breed reported; golden retrievers, Saint Bernards, Newfoundlands,
Irish setters, and Brittany spaniels are also overrepresented

Question 3

What breeds are most commonly affected by Laryngeal paralysis polyneuropathy
disease complexes?

Answer 3

Dalmatians, Rottweilers,
Leonberger dogs, Pyrenean mountain dogs, and American Staffordshire terriers.

Question 4

What is the primary function of the cricoarytenoideus dorsalis muscle in dogs?

Answer 4

Enlarges the glottis during inspiration

Question 5

What is the recommended anesthetic agent for evaluating laryngeal function in dogs, according to recent studies?

Answer 5

Alfaxalone

Question 6

Which of the following surgical techniques is considered the treatment of choice for laryngeal paralysis in severely affected dogs?

A) Bilateral arytenoid lateralization
B) Unilateral arytenoid lateralization
C) Partial laryngectomy
D) Permanent tracheostomy

Answer 6

B) Unilateral arytenoid lateralization

Question 7

T/F: The larynx of the cat differs from that of the dog because the arytenoid cartilage lacks cuneiform and corniculate processes.

Answer 7

T

Question 8

T/F: Thyroid supplementation can resolve clinical signs associated with laryngeal paralysis in dogs.

Answer 8

False. While hypothyroidism is commonly concurrent with acquired laryngeal paralysis, a direct causal link has not been established. Thyroid supplementation can help with systemic effects like weight loss but does not address the underlying neuropathy that causes laryngeal paralysis, making it insufficient to resolve the primary clinical signs.

Question 9

T/F: Aspiration pneumonia is a common complication in dogs both before and after surgical intervention for laryngeal paralysis.

Answer 9

T

Question 10

T/F: Laryngeal collapse is most commonly associated with brachycephalic obstructive airway syndrome in dogs.

Answer 10

T

Question 11

T/F: The majority of cats with unilateral laryngeal paralysis do not require surgical intervention.

Answer 11

False (Cats with unilateral dysfunction can have significant clinical signs and may require surgical intervention.)

Question 12

Discuss the significance of the caudal laryngeal nerve in the pathophysiology of laryngeal paralysis in dogs.

Answer 12

The caudal laryngeal nerve, a terminal segment of the recurrent laryngeal nerve, is responsible for innervating all intrinsic muscles of the larynx except the cricothyroid muscle. Damage to this nerve leads to laryngeal paralysis, where the arytenoid cartilages and vocal folds fail to abduct during inspiration, causing upper airway obstruction and clinical signs such as stridor, respiratory distress, and exercise intolerance.

Question 13

What are the key diagnostic tools used to confirm laryngeal paralysis in dogs, and what challenges might arise during diagnosis?

Answer 13

Key diagnostic tools include physical examination, neurologic examination, thoracic radiographs, and laryngeal examination under light anesthesia. Challenges during diagnosis can include paradoxical arytenoid movement, where the arytenoids move inward during inspiration due to negative intraglottic pressure, potentially leading to false-negative results.

Question 14

Explain the relationship between laryngeal paralysis and generalized polyneuropathy in geriatric dogs.

Answer 14

Laryngeal paralysis in geriatric dogs is often an early sign of a progressive generalized polyneuropathy. This condition affects multiple peripheral nerves, leading to a gradual decline in motor function, including the muscles that control the larynx. Over time, these dogs may develop additional neurologic signs, reflecting the systemic nature of the disease.

Question 15

Describe the clinical presentation and management options for laryngeal masses in cats.

Answer 15

Laryngeal masses in cats can present with significant respiratory distress, noisy breathing, and potentially obstructive symptoms. Management options depend on the nature of the mass and may include surgical resection, debulking, steroid therapy, and in some cases, permanent tracheostomy. Prognosis varies depending on the type and extent of the mass.

Question 16

What factors influence the decision to perform surgery for laryngeal paralysis in dogs, and what are the potential postoperative complications?

Answer 16

The decision to perform surgery is influenced by the severity of clinical signs, quality of life, and presence of bilateral laryngeal paralysis. Unilateral arytenoid lateralization is often the surgery of choice. Potential postoperative complications include aspiration pneumonia, persistent respiratory distress, and progression of underlying neurologic disease, all of which can significantly impact long-term outcomes.

Question 17

What is the most common complication associated with temporary tracheostomy in dogs with laryngeal paralysis?

Answer 17

Mucus production and tube clogging

Question 18

In the management of laryngeal paralysis, which of the following is NOT a risk factor for developing postoperative aspiration pneumonia?

A) Preexisting aspiration pneumonia
B) Postoperative megaesophagus
C) Administration of opioid analgesics before discharge
D) Concurrent neoplastic disease

Answer 18

A) Preexisting aspiration pneumonia (Recent studies suggest that preexisting aspiration pneumonia was not associated with an increased risk of developing postoperative aspiration pneumonia

Question 19

What is the primary clinical sign of early laryngeal paralysis in dogs?

A) Acute respiratory distress
B) Severe coughing and gagging
C) Voice change
D) Dysphagia

Answer 19

C) Voice change

Question 20

Which imaging modality is mentioned as helpful in diagnosing laryngeal paralysis without the need for heavy sedation or general anesthesia?

A) Computed Tomography (CT)
B) Magnetic Resonance Imaging (MRI)
C) Thoracic Radiography
D) Ultrasonography (Echolaryngography)

Answer 20

A) Computed Tomography (CT)

Question 21

T/F: Bilateral arytenoid lateralization is sometimes recommended in dogs to reduce the risk of aspiration pneumonia.

Answer 21

F: Bilateral arytenoid lateralization is not recommended due to unacceptable morbidity.

Question 22

T/F: In dogs with laryngeal paralysis, esophagography should be routinely performed to assess for esophageal dysfunction.

Answer 22

F: Esophagography should be considered but weighed against the risk of barium aspiration.

Question 23

T/F: Laryngeal collapse can occur as a result of chronic upper airway obstruction associated with brachycephalic obstructive airway syndrome.

Answer 23

T

Question 24

Describe the pathophysiology leading to laryngeal collapse in brachycephalic breeds and how it differs from laryngeal paralysis.

Answer 24

Laryngeal collapse occurs due to chronic upper airway obstruction, leading to increased airway resistance and negative intraglottic pressure. Over time, this causes cartilage fatigue and degeneration, resulting in collapse. Unlike laryngeal paralysis, which involves a loss of nerve function leading to immobility of the arytenoids, laryngeal collapse is a structural failure due to chronic stress on the laryngeal cartilages.

Question 25

What is the clinical utility and what the limitations of using doxapram HCl during laryngoscopy for diagnosing laryngeal paralysis.

Answer 25

Doxapram HCl is used to increase respiratory rate and effort during laryngoscopy, enhancing the ability to observe laryngeal motion. While it improves the diagnostic accuracy, there are limitations such as the risk of inducing paradoxical arytenoid movement, which could lead to a false-negative diagnosis.