Respiratory disease is a common presentation in small animal practice, and veterinary technicians play an essential role in identifying early clinical signs. One of the most important skills for VTNE® preparation and clinical practice is learning to localize respiratory disease to either the upper or lower respiratory tract using observable clinical signs.
Recognizing upper vs. lower disease allows technicians to assist veterinarians with triage decisions, diagnostic planning, and patient stabilization. Respiratory distress can rapidly become life-threatening, so quick recognition and action is critical.
Understanding the Anatomy of the Respiratory Tract
Think of the respiratory system as comprised of two major sections.
The upper respiratory tract (URT) includes the nose, nasal passages, sinuses, pharynx, and larynx. These structures primarily function to filter, warm, and humidify inhaled air.
The lower respiratory tract (LRT) includes the trachea, bronchi, bronchioles, and alveoli. These structures both facilitate airflow into the lungs and allow gas exchange.
Clinical signs help determine which region of the respiratory tract is affected, allowing the veterinary team to narrow the differential diagnoses early in the evaluation process.
Clinical Signs of Upper Respiratory Disease
Disease of the URT commonly produces nasal discharge, sneezing, increased inspiratory effort/time, and/or respiratory noise (stridor/high-pitched or stertor/low-pitched).
Technicians should assess several characteristics of nasal discharge:
- Color: serous (clear/watery), mucoid (cloudy/white), purulent (thick and yellow/green), or hemorrhagic (red/bloody – called “epistaxis”)
- Odor
- Unilateral vs. bilateral
For example, unilateral purulent discharge may suggest a nasal foreign body or tumor and is more likely to have a foul odor. Bilateral mucoid discharge may indicate infectious or inflammatory disease. Epistaxis can occur with nasal tumors, fungal infections such as aspergillosis, or systemic diseases affecting platelet function.
Clinical Signs of Lower Respiratory Disease
Disease of the LRT typically causes dyspnea (difficulty breathing), tachypnea (rapid breathing), and pale or cyanotic gums if severe.
Dyspneic patients may appear anxious or reluctant to move and exhibit:
- Increased respiratory effort (dyspnea)
- Rapid breathing (tachypnea)
- Abdominal involvement during respiration
- Nasal flaring and/or neck stretching
Common causes of dyspnea include:
- Tracheal collapse/narrowing
- Congestive heart failure
- Feline asthma
- Pneumonia
- Pleural effusion
Because dyspnea can quickly become life-threatening, veterinary teams must stabilize these patients with oxygen therapy and anxiolytics (to help calm them) before diagnostic imaging or other procedures. The stress of restraint for diagnostics in a dyspneic patient can be enough to cause respiratory failure and death.
Remember, tachypnea may occur independently of respiratory disease, occurring secondary to pain, stress, or metabolic disorders. Rule out primary respiratory distress prior to looking for other causes.
Overlapping Clinical Presentations
Some clinical signs do not localize easily to one portion of the respiratory tract.
Coughing is a classic example. It can occur with upper respiratory diseases such as infectious tracheobronchitis (kennel cough) or with lower airway conditions such as feline asthma.
Veterinary technicians must also recognize that pet owners frequently misinterpret coughing episodes in cats as hairball vomiting. A coughing cat typically crouches with its neck extended and produces repeated cough sounds, rather than the abdominal contractions seen with vomiting. Similarly, dogs with tracheobronchitis often bring up mucous at the end of their cough, which owners may erroneously describe as vomiting.
Another consideration is patients with concurrent upper and lower respiratory disease. An example could be a patient with an upper respiratory viral infection that compromised the respiratory defenses and lead to bacterial pneumonia.
Diagnostic Testing for Respiratory Disease
After initial stabilization, several diagnostic tests can help identify the underlying cause of respiratory disease.
Common diagnostic tools include:
- Thoracic-focused assessment with sonography (TFAST) to detect pleural/pericardial effusions and some parenchymal diseases
- Thoracic radiographs to evaluate lung patterns, heart, trachea, mediastinum, and other intrathoracic structures
- Pulse oximetry to measure oxygen saturation levels
- Infectious disease testing, including heartworm testing and PCR for respiratory pathogens
- Arterial blood gas to determine blood oxygenation
Advanced diagnostics may include thoracocentesis, CT imaging, rhinoscopy, or bronchoscopy, depending on the Ddx list.
From Clinical Signs to Diagnosis: The Technician’s Role
By carefully evaluating airway signs, technicians can help localize disease within the respiratory tract and assist the veterinary team in making timely diagnostic and treatment decisions.
Mastering respiratory clinical sign recognition improves VTNE® readiness and allows veterinary technicians to contribute more effectively to patient assessment and care.
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