Canine Reverse Sneezing Study Guide

Overview and Clinical Importance

Reverse sneezing, also known as paroxysmal respiration or inspiratory paroxysmal respiration, is a relatively common respiratory event in dogs characterized by rapid, forceful inhalation through the nose producing a distinctive snorting or honking sound. Unlike a regular sneeze where air is forcefully expelled through the nose, reverse sneezing involves the rapid inhalation of air, creating what appears to be labored breathing.

This condition is triggered by irritation of the nasopharynx (the area at the back of the nose, above the hard and soft palates), which initiates a reflex resulting in a series of multiple, loud, sudden, rapid inhalations. During an episode, the glottis (opening to the trachea) partially closes, and the dog extends its neck while making snorting sounds as it attempts to clear the irritation.

Relevant Anatomy

Upper Respiratory Tract Structures

Nasopharynx: The portion of the pharynx located dorsal to the soft palate, extending from the caudal nasal cavity (choanae) to the intrapharyngeal opening. This is the primary site of irritation triggering reverse sneezing. It is bounded dorsally by the basisphenoid bone, laterally by the pterygoid bone, and ventrally by the soft palate.

Soft Palate (Velum Palatinum): The musculomembranous partition extending caudally from the hard palate that separates the nasopharynx (dorsal) from the oropharynx (ventral). In normal dogs, the soft palate overlaps the tip of the epiglottis. In brachycephalic breeds, the soft palate is often elongated and/or thickened, contributing to airway obstruction and increased frequency of reverse sneezing.

Oropharynx: The caudal portion of the oral cavity bounded dorsally by the ventral aspect of the soft palate, ventrally by the root of the tongue, and laterally by the tonsillar fossae containing the palatine tonsils.

Larynx: A complex cartilaginous structure that controls the entrance to the trachea. The epiglottis protects the tracheal opening during swallowing. The laryngeal saccules (lateral ventricles) are located adjacent to the vocal folds and can become everted in brachycephalic airway syndrome.

Nasal Conchae (Turbinates): Scrolled bones projecting into the nasal cavity that increase surface area for warming, humidifying, and filtering inspired air. In brachycephalic dogs, hypertrophic turbinates can contribute to nasal obstruction.

Pathophysiology and Mechanism

Reflex Mechanism

Reverse sneezing is a mechanosensitive aspiration reflex triggered by irritation of the nasopharyngeal mucosa. The proposed mechanism involves muscle spasm at the junction of the back of the mouth and throat, causing the soft palate to become irritated. This irritation causes spasms in the soft palate musculature, resulting in temporary narrowing of the tracheal entrance. Because the trachea is narrowed, the dog cannot inhale a full breath of air, resulting in forceful attempts to inhale through the nose.

Sequence of Events During an Episode

• Nasopharyngeal irritation triggers the reflex
• The dog adopts an orthopneic position (neck extension, elbow abduction)
• Soft palate spasm causes partial tracheal narrowing
• The glottis partially closes
• Rapid, forceful inspiratory efforts produce the characteristic snorting sound
• The episode resolves spontaneously, typically within 30 seconds to 1 minute

Etiology and Triggers

Common Triggers

Breed Predisposition

Reverse sneezing can occur in any breed but is more commonly reported in dogs weighing less than 15 kg and in brachycephalic breeds. It occurs equally in males and females, neutered or intact, and can occur at any age.

Clinical Presentation

Characteristic Signs During an Episode

• Sudden onset of rapid, forceful inspirations through the nose
• Loud snorting, snuffling, or honking sounds
• Extension of head and neck (orthopneic posture)
• Standing still with elbows abducted
• Expansion of chest during inspiration attempts
• Mouth typically remains closed
• Eyes may bulge slightly
• Episode duration: typically 30 seconds to less than 1 minute

Key Clinical Features

• Dog is completely NORMAL before and after episodes
• No respiratory distress between episodes
• Episodes resolve spontaneously
• No nasal discharge, coughing, or other respiratory signs (unless underlying pathology exists)
• Mucous membranes remain pink throughout

Differential Diagnosis

It is essential to differentiate reverse sneezing from other conditions that may present with similar respiratory sounds or appear to cause breathing difficulty.

Diagnostic Approach

Initial Assessment

Diagnosis of uncomplicated reverse sneezing is typically based on medical history, clinical signs, and physical examination. In many cases, no diagnostic testing is needed if the presentation is classic and episodes are infrequent.

History Taking

• Duration, frequency, and progression of episodes
• Triggering factors (excitement, eating, environmental exposure)
• Associated signs (nasal discharge, coughing, exercise intolerance)
• Behavior between episodes
• Video recording of episodes is extremely helpful

Physical Examination

• Complete respiratory examination
• Evaluation of nasal airflow (both nostrils)
• Assessment of nares (stenotic nares in brachycephalics)
• Auscultation of upper and lower airways
• Palpation of trachea (for tracheal sensitivity)
• Oral examination (if possible without sedation)

When to Pursue Advanced Diagnostics

Consider further workup if:

• Episodes become more frequent or severe
• Episodes last longer than 1 minute
• Nasal discharge (especially unilateral or bloody) is present
• Coughing, exercise intolerance, or cyanosis develop
• Dog appears distressed or has difficulty breathing between episodes
• Response to empirical treatment for allergies/mites is poor

Advanced Diagnostic Options

Treatment and Management

Immediate Episode Management

Most episodes of reverse sneezing resolve spontaneously within 30 seconds to 1 minute and require no intervention. However, owners can try the following techniques to help shorten episodes:

• Stay calm: Dogs can sense owner anxiety, which may prolong episodes
• Gentle throat massage: Lightly massage the throat to help relax the spasm
• Brief nostril occlusion: Briefly cover nostrils for a few seconds to encourage swallowing, which clears the irritant
• Gentle blowing on face: Light blowing on the dog's face may help trigger swallowing
• Offer water: Encouraging drinking or licking can stimulate swallowing and clear irritants
• Tongue depression: Gently depressing the tongue opens the mouth and aids airflow through nasal passages

Medical Treatment Options

Environmental Management

• Use air purifiers to reduce airborne allergens
• Minimize exposure to smoke, perfumes, and strong chemicals
• Regular cleaning to reduce dust
• Use harness instead of collar to avoid throat pressure
• Maintain healthy weight (especially in brachycephalics)
• Avoid triggers when possible (excitement, rapid eating)

Prognosis

The prognosis for dogs with reverse sneezing is excellent. The condition is benign and does not cause any lasting harm or affect the dog's quality of life. Most dogs experience reverse sneezing episodes intermittently throughout their lives without progression or complications.

In many cases, the underlying cause remains idiopathic despite thorough workup. Dogs with identifiable and treatable underlying conditions (allergies, nasal mites, foreign bodies) have excellent outcomes with appropriate therapy. Even brachycephalic dogs that require surgical correction of elongated soft palate generally have good outcomes, with reduced frequency of reverse sneezing episodes post-operatively.

Memory Aids and Board Tips

REVERSE Mnemonic

R - Rapid inspiratory efforts (air pulled IN through nose) E - Episodes are brief (less than 1 minute typically) V - Virtually always benign E - Extends neck during episode R - Returns to normal immediately after S - Snorting/honking sound E - Excitement, allergens, irritants are common triggers

Key Differentiators

"Reverse Sneezing = IN, Normal Sneezing = OUT" In reverse sneezing, air is rapidly pulled INWARD through the nose (inspiratory). In normal sneezing, air is forcefully pushed OUTWARD through the nose (expiratory).

"Reverse Sneezing vs. Collapsing Trachea" Reverse sneezing: Inspiratory paroxysm, dog NORMAL between episodes, benign Collapsing trachea: Honking COUGH, PROGRESSIVE, can cause cyanosis, requires treatment