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Define the following:




  • Hypoxia = oxygen levels in the blood, lungs, and/or tissues is low
  • Hypoxemia = insufficient oxygenation of the blood
    • Resp. stimulant when PaO2 < 50mmHg (normal = 90-110mmHg)
  • Hypercapnia = inc. CO2 levels, resp. stimulant
    • Most powerful



What is it?

What's normal?

When will it occur?

  • Bluish to red-purple color in the tissues due to increased amounts of deoxygenated or reduced hemoglobin
  • Animal w/ normal hematocrit
  • Needs an arterial SaO2 73 and 78% pulse ox (PaO2 39-42mmHg) before cyanosis is found




What should you avoid?

What should you give to the animal?

  • Difficult or labored breathing
  • Avoid excessive stress or struggling, and avoid dorsal recumbency for rads
  • Give animal additional oxygen immediately


Define the following:




  • Stridor = high pitched inspiratory noise, rapid flow of air passed a rigid obstruction or paralysed/collapsed larynx
  • Stertor = low-pitched inspiratory noise, gurgling or snoring sound, produced as air passes soft tissue obstruction
    • Normal in brachycephalic dogs
  • Orthopnea--adopt a strange position
    • Sternal recumbency w/ elbows abducted, the neck extended and open-mouth breathing


Respiratory disease

Diagnostic approach (steps)

4 disorders

  • Diagnostic approach
    • History/clinical signs
    • PE/localization of disease
    • Diagnostics/procedures
    • Common drugs used in therapy
  • Disorders
    • Nasal disorders
    • Airways--laryngeal, tracheal, bronchial disorders
    • Pulmonary parenchymal diseases
    • Pleural space diseases


Respiratory diseases

What is included in the history (diagnostic approach)?

  • What is the signalment
    • Ciliary dyskinesia--generally younger
    • Neoplastic--generally older
    • Breed
      • Brachycephalic--stertor
      • Mesocephalic
      • Dolichocephalic--obstructions, fungal inf.
  • How long has it been going on for?
    • Acute signs
      • Progressive
    • Chronic
  • Where is the location


Differentiate between clinical signs of upper and lower respiratory diseases

  • Upper = nares to larynx
  • Lower = larynx to lungs


What should you look for during the physical exam?

  • What can you see
    • Look for nasal discharge/disease
    • Is there respiratory distress
  • What can you hear
    • Sneezing
    • Breathing louder than normal
    • Evidence of a cough
    • What can be heard on auscultation
  • What can you feel/touch
    • What can you palpate


Nasal disease


Age, breed


Nasal disease: physical exam


Facial palpation


  • Bilateral airflow?
    • Glass slide technique, wisp of cotton wool
  • Facial palpation
    • Pain?
    • Symmetry vs. asymmetry?
    • Normal ocular retropulsion?
      • Place thumbs over eyelids and gently press backwards, upwards, medially, laterally (checks for masses)


Nasal disease: physical exam

Oral exam

Nasal discharge

  • Oral exam
    • Check dentition and dental arcade
    • Check hard palate for abnormalities
    • Check soft palate to see that it can be easily pressed upwards (anesthetized)
  • Nasal discharge
    • Characterize discharge:
      • Serous (clear), mucoid (not clear), mucopurulent (cloudy), purulent (white/yellow), hemorrhagic (bloody)
      • Unilateral vs. bilateral (doesn't really matter when hemorrhagic)
      • Persistent vs. intemittent
    • Duration, has it changed over time
      • Acute nasal disease often accompanied w/ sneezing
      • Chronic nasal disease often has purulent to hemorrhagic discharge


Nasal disease: physical exam


  • Localizes disease to nasal cavity
  • Protective mech. of upper airways
  • May have concurrent nasal discharge
  • Normal sneezing: expiratory, forceful
    • Occasional, intermittent, persistent, paroxysmal
  • Reverse sneezing
    • Inspiratory
  • Duration?


Physical exam

Breathing sounds

  • Stertor (low pitch, snoring)
    • Brachycephalic airway syndrome
  • Stridor
    • Laryngeal paralysis
    • Tracheal collapse
    • Nasopharyngeal stenosis


Physical exam

Cough--hallmark of?

  • Hallmark of a tracheal or pulmonary disease (lower airways) or cardiac failure
    • Use the signalment, history, clinical finding and rads to be able to distinguish between these causes
  • Forceful expiratory effort/protective reflex


Physical exam

Cough--triggers? Classification?

  • Triggers include:
    • Irritant receptors that lie between epithelial cells lining the airways (cough receptors) 
    • Inflammatory products of neutrophils or eosinophils
    • Excessive secretions
    • Airway compression or collapse
  • Classified as
    • Dry/non-productive
    • Moist/productive
    • Harsh/intermittent or paroxysmal (once it starts, gets progressively worse)


Beautiful massive chart of cardiogenic vs. non-cardiogenic coughing?


Respiratory distress terms


Respiratory distress


  • Panting
    • Dissipates heat--can be normal in dogs
    • Cats: assoc. w/ stress or resp distress
  • Resp distress
    • Most frequently assoc. w/ lower airway disease
    • Dogs w/ bilateral laryngeal paralysis (upper airways) are also in distress


Respiratory distress (dyspnea)



  • Insufficient oxygen in inspired air
  • Insufficient ventilation
  • Insufficient circulation
  • Insufficient erythrocytes
  • Abnormal or low hemoglobin concentrations



  • Insufficient oxygen can result in cyanosis
    • Color of mucous membranes
  • Causes
    • Lack of O2--upper/lower resp disease
    • Abnormal hemoglobin--toxins
    • Cardiac dz
    • Pulmonary dz
    •  Cardiopulmonary arrest


Respiratory patterns

Inc. inspiratory effort

Inc. expiratory effort

Shallow breaths and tachypnea

  • Inspiratory
    • Usually upper resp dz
  • Expiratory
    • Usually lower resp dz
  • Shallow/tachypnea
    • Indicates restrictive resp pattern
      • Pulmonary/pleural/mediastinal dz
      • Often orthopneic posture
      • Discordant motion of chest and abdominal muscles--> suspect flail chest or resp muscle fatigue


Pulmonary sounds

Normal lung sounds

  • Normal lung sounds are bronchovesicular
  • Bronchial--loudest over hilus during expiration
    • Mvt of air through tracheal bifurcation region
  • Vesicular--loudest on inspiration at periphery of lungs, normal air filling lungs "rustling of leaves" (very soft sounds)
  • Normal lungs will have normal bronchovesicular sound, but w/ disease you can have harsh or increased bronchovesicular sound


Pulmonary auscultation (various sounds)

  • Parynchymal disease--adventitial sounds
  1. Crackles--snapping open of airways that have closed due to fluid in/around them (rice krispies)
  2. Wheezes--caused by airflow through narrow opening--airways are constricted/narrowed
  3. Snaps--loud snaps over hilus at end of expiration indicates collapse of the intrathoracic trachea, carina, or mainstem bronchi
  4. Goose honks--sound w/ tracheal collapse
  5. Pleural friction rubs--creaking/grating sound due to roughened pleural surfaces rubbing against each other


Pulmonary auscultation

Pleural disease


  • Pleural effusion
    • Lung sounds auscultated dorsally
      • Lungs floating in fluid
      • Muffled sounds ventrally
      • Heart sounds also reduced
  • Pneumothorax
    • Abscence of lung sounds dorsally due to compression
    • Only present in ventral field
  • Both are emergencies--need to aspirate ASAP


Pulmonary percussion: distinguish between air and fluid density

  • Use your finger/small mallot to strike chest cavity and listen to the sound
    • Fluid gives dull sound
    • Pneumothorax will give inc. resonance
  • Difficult in small dogs and cats


Minimum data base

  • Remember: stabilize patient before doing any tests
    • Cats often will need a couple of hours in oxygen chamber before any additional tests are done
  • CBC, biochem, fecal, HW check (if required)
  • Thoracic rads required in most situations (stabilize first)


T/F: X-rays are usually helpful in nasal disease cases

FALSE--x-rays are not sensitive at all with nasal diseases



Performed when?

Otoscope vs. endoscope

Endoscopy steps?

  • Performed after imaging
  • Otoscope--limitations of depth, visibility, biopsy
  • Endoscope--rigid or flexible; video-endoscope ideal
    1. GA, cuff endotrach tube
    2. Often perform pharyngoscopy at this stage to assess nasopharynx
    3. Block off oropharynx w/ swabs
    4. Enter each nare--examine dorsal, middle, ventral, and common meatus
    5. Biopsy abnormal or normal areas if required



Blind biopsies

Do not pass medial canthus of eye (will go into brain--> bad news bears)



Evaluation of what?

  • Evaluates the larynx, trachea, and bronchi
    • Evidence of tracheal collapse, foreign body, or neoplasm?
    • Look at tracheal bifurcations and at the dif. bronchi
    • Samples taken for cytology, culture and sensitivity and sometimes a fine needle aspirate or a biopsy is taken 
    • Contraindicated in patients w/ severe respiratory distress (procedure requires general anesthesia)


What is included in the extended data base (9)?

  • Nasal flush
  • Cytobrush
  • Transtracheal aspirate
  • Bronchoalveolar lavage
  • FNA of lung
  • Serology and/or PCR
  • Cytology
  • Biopsy
  • Culture and sensitivity