Exam #4: Respiratory Pt. 1 Flashcards
What are the most common infectious equine respiratory diseases (4)?
1) Strangles (Strep equi or Strep zoo)
2) EHV-1, EHV-4 (EHV-2)
3) Equine influenza
4) Equine viral arteritis
What are the two general questions we ask when presented with respiratory signs?
- Contagious or non-contagious
- Upper or lower respiratory tract
Historical questions we ask with respiratory cases
- Daily management
- Performance
- Recent travel or movement
- Medical and vax history
- General history of the animal
- Farm history
- Clinical signs of animal, duration, severity
- Previously treated? Effective?
- Diet and feed
- Deworming history
- Current activity
- Other animals affected?
- Housing, ventilation, bedding types
How to perform the PE of a respiratory case
- If traveled, let them settle for 15 minutes
- Observe from a distance = mental status, demeanour, stance, dyspnea, noise, RR, nasal discharge
- TPR = prior to manipulating the horse
Where does inspiratory noise localize us to?
Upper respiratory tract
Where does expiratory noise localize us to?
Lower respiratory tract
Ratio of normal inspiratory, expiratory and pause phase of respiration?
1:1:1
When do we consider coughing chronic?
When it’s occurred for > 3 weeks
- Rule acute causes of cough
What do you suspect if there’s coughing and abnormal lung sounds?
Pulmonary or lower respiratory tract disease
What causes coughing?
Stimulation of irritant receptors in the airways - defense mechanism to enhance airway clearance
Common origin of hemoptysis
Comes from airway or lung parenchyma = indicative, usually, of lower respiratory tract disease
Common cause of nasal flaring
+ Distension of nares on inspiration to increase air intake
*Usually indicative of upper respiratory disease
Where does nasal discharge localize you to?
Can originate from any level of the respiratory tract
- Lower respiratory tract discharge can be swallowed and unapparent
DDx for nasal discharge (3)
- Respiratory infection - sinusitis, rhinitis, pneumonia, etc
- Tooth root abscess
- CHOKE = make sure to rule it out
DDx and origin of epistaxis (2)
- Can be from both upper and lower respiratory tract
- May be swallowed if from lower respiratory tract
- DDx = bleeding disorder
DDx for conjunctivitis (3)
- Conjunctivitis
- Obstruction of nasolacrimal duct
- Obstruction of nasal passage, guttural pouch, or sinuses
What does erosion of the mucocutaneous border of the nostrils indicate?
Chronic nasal discharge
Normal adult and foal RR’s
- Adult = 12- 20 bpm
- Foal post-foaling-30 min = 60-80 bpm
- Foal 1-12 hrs post foaling, sternal = 30-40 bpm
- Foal (1 month) = 12-30 bpm
*Activity level and temperature affect respiratory rate = compare to normal horses if you’re concerned
Eupnea
Normal, quiet, effortless breathing with 1:1:1 ratio (ins, exp, pause)
Tachypnea
Rapid frequency and shallow depth, or small tidal volume breathing
Hyperpnea
Increase in depth and rate of breathing
Apnea
Period of no respiratory effort is made and air flow has ceased
Dyspnea
Difficulty breathing - animal is distressed, increased work to breathe is evident
+ Heave line w/ dyspnea = acute
+ Heave line w/ eupnea = chronic problem
Hypoventilation
> ARTERIAL SAMPLE ONLY
- Respiratory pattern that alters gas exchange to cause arterial HYPERCAPNIA (high PaCO2)
Hyperventilation
> ARTERIAL SAMPLE ONLY
- Respiratory pattern that increases alveolar ventilation and results in arterial HYPOCAPNIA (low PaCO2)
Cyanosis
> When the Hgb isn’t saturated (< 80%)
- Occurs with PaO2 < 50 mm Hg
+ Bluish discoloration of the mucous membranes
*Anemia may mask the signs of cyanosis
> > Examine PaO2, PaCO2, and oxygen saturation
Localization and respiratory phase of stridor
+ Abnormal respiratory sign, high pitched (turbulent air flow), usually INSPIRATORY
- Usually due to upper airway disease
*Compare sound over trachea to lung sounds to ensure it’s not a referred airway noise
PE of the upper respiratory tract - things to look for
- Symmetry of posture and airflow
- Respiratory movement?
- Inspiratory flaring (occurs with increased respiratory effort)
- Air flow, normally, doesn’t create any noise
- Paralysis of nostril will result in collapse = inspiratory obstruction
- Exertion or gallop-normal expiratory sound (“high blowing”)
- Malodorous?
- Skin depigmentation from chronic discharge
- Nasal discharge
- Epistaxis
What does skin depigmentation of the nares indicate?
Chronic nasal discharge
What does asymmetrical nasal airflow, unilateral nasal discharge, or epistaxis indicate?
Upper respiratory lesion, rostral to the caudal extent of the nasal septum
What does a malodorous nasal discharge indicate?
Likely a bacterial infection, commonly anaerobic
Things to examine if you suspect sinusitis
- Facial symmetry or swelling
- Look inside mouth = cheek teeth, tongue, hard palate deviation
- Percuss the sinuses, compare side to side (sound is louder if mouth is held open)
Things to do during your larynx, trachea, and LN exam
> Larynx = palpate for symmetry, evaluate w/ endoscope (slap test?)
Trachea = squeeze trachea and look for cough, palpate for cartilage abnormalities
LN’s = palpate retropharyngeal and submandibulars (throat-latch area) for swelling
- DDx = LN, salivary glands
Examination of the thorax
- Observe respiratory rate and pattern at a distance
- Expiratory = double effort = abdominal lift during natural diaphragmatic relaxation, 2nd “lift” with muscular contraction of body wall
- Auscultation of the ENTIRE lung field (3-17 ICS)
- Compare noise to over trachea and larynx
- Use a rebreathing bag to accentuate normal and abnormal lung sounds
Heave line, and what does it indicate?
Outline to a hypertrophied external abdominal oblique muscle
- Indicates increased EXPIRATORY effort
- May be normally well defined in a fit horse
Is open mouth breathing a problem?
YES - ER CASE (horses are obligate nose breathers)
True or false - you should use a rebreathing bag to examine every respiratory case
FALSE - contraindicated in horses with increased respiratory effort at REST
Crackles, where do they come from, when do you hear them?
> Snapping open of collapsed airways, implies fluid or infiltrate accumulation in airways/alveoli
- Commonly heard on INSPIRATION
- Common with pneumonia
Wheezes, where do they come from, when do you hear them
> Longer, musical sound due to resonant vibration of airway walls before closing or opening
- Implies decreased airway lumen diameter = thickening of airway or collapse due to surrounding pressure
- More commonly EXPIRATORY, but can be inspiratory
Absence of lung sounds dorsally and ventrally mean?
- Dorsal = pneumothorax
- Ventral = pleural effusion, lung consolidation, or mass
Dx? Pain on palpation of ICS
Pleurodynia, usually due to pleuritis or trauma
Diagnostics for respiratory disease (besides history and PE)
- Arterial blood concentrations
- U/S
- Radiographs
- Endoscopy
- Fluid collection = sinuses, guttural pouch, tracheal, bronchoalveolar, thoracic –> PCR, culture, cytology
- Biopsy
Pros/cons of percutaneous tracheal lavage
+ Cleaner sample = aseptic sampling avoids URT contamination = good for CULTURE and CYTOLOGY
+ Lower cost
+ Simpler than endoscopic
- Can cause tracheal reactions
- Can lose sampling tube
Pros/cons of transendoscopic tracheal lavage
+ Avoids complications of transtracheal approach
+ Can visualize your specimen
*In good agreement with TT approach
- Can get oral and pharyngeal contamination
- Use guarded tubing to prevent contamination if you’d like to culture
What diagnostic do you use if you suspect diffuse alveolar disease?
Bronchoalveolar lavage - use with endoscope and cuffed BAL tube
Comparison of TTW and BAL, which do you do first if you do both
> Do TTW first and BAL second (will contaminate trachea)
> TTW = samples all parts of lung
- Good for focal disease
- GOOD for culture
- Worse for cell morphology
> BAL = samples small segments of the lung
- Good for diffuse disease
- Questionable for culture
- BETTER cell morphology
What is the diagnostic of choice to examine the pleural surface and space?
> U/S - atlectasis, pleural effusion, monitor progression
*Can guide thoracocentesis (CRANIAL to rib at 6-7th ICS)
*Can also be used to evaluate the parenchymal disease = consolidated (difficult on aerated lung) or abscesses near the surface
Bacterial and viral samples to send to lab for diagnostics
- Bact = flush or guttural pouch or nasal cavity, sterile swab (w/ approriate media)
- Virology = collect EARLY in disease, nasopharyngeal swabs - GOOD, send in viral transport media, keep swabs cold and damp
Where can we draw arterial samples from?
- Facial artery (ventral)
- Transverse facial artery
- Carotid artery, if they won’t sit still
- Sedatives can affect your blood gas results
- Keep pressure on site 3-5 minutes after sampling
- Analyze within 10 min or place on ice and examine in 90 min
Causes and level of hypoxia
> Hypoxia = PaO2 < 85 mm Hg
- Vent/perfusion inequality
- Hypoventilation
- Low inspired O2
- Shunts
- Diffusion impairment
*Use the arterial and alveolar gradient for oxygen to diagnose the source of hypoxemia
What is the most sensitive indicator for adequacy of ventilation?
PaCO2 (also assesses perfusion)
DDx for nasal discharge in a young foal (6 mo)
1) Sinusitis
2) Guttural pouch disease, Ex: empyema
3) Pharyngitis, abscess
- Lymphoid hyperplasia = common in young horses, but doesn’t cause nasal discharge
Most common cause of lower respiratory signs in young foals
Pneumonia - bacterial (MOST COMMON), fungal, +/- viral
Diagnostic tests of young foal respiratory disease
- CBC
- Endoscopy
+/- Radiographs of lungs or guttural pouch - Thoracic U/S
+/- Blood gas if severely infected (difference between arterial and alveolar O2 to ID mismatch) - Cytology and culture of airway infiltrate
Dx? Bilateral nasal discharge in a young foal, retropharyngeal swelling, history of URT infections, CBC = mature neutrophilia, hyperfibrinogenemia, fluid line on guttural pouch rads
Guttural pouch empyema, etiologic agent = Strep equi equi or Strep zoo
*Suspect the animal also has LRT disease
Treatment of guttural pouch emypema
- Flush and drain guttural pouches = common to have to repeatedly flush
- Look for chondroids (flushing won’t help)
- Systemic antibiotics = penicillin for Strep
- NSAID’s (Banamine)
- Elevate feed off ground
- Surgery if irresponsive after 14 days or if chrondroids are present
Medial and lateral guttural pouch contents
- Medial = LARGER, where most exudate accumulates = internal carotid a. CN IX-XII (branch of X), cranial sympathetic ganglia
- Lateral = external carotid a., maxillary a., CN V, VII (branch of), VIII
Pathology of empyema in younger foals
Ascending infection from the lower respiratory tract = chronic and localized in nature
Can also be a rupture of a retropharyngeal LN
Dx and Tx? Non-painful, soft swelling behind the mandible, dyspnea, dysphagia
> Guttural pouch tympany = redundant fold of plica salpingopharyngea
- Medical tx = pass cannula through nose to release air, leave it in for 6 weeks to see if it enlarges the opening
- Surgical tx = enlarge the opening
Dx? Unilateral or bilateral spontaneous epistaxis in a resting animal, dysphagia, Horner’s syndrome, facial paralysis, laryngeal hemiplegia
Guttural pouch mycosis, commonly due to Aspergillosis
*Likes to grow on the internal carotid or branches of external maxillary arteries
DDx = EIPH but doesn’t have neurologic signs
How do you differentiate between EIPH and guttural pouch mycosis?
- Does it occur at rest or after exercise?
- Do you concurrent neurologic signs?
Treatment of guttural pouch mycosis
- Stop bleeding with surgery and fluids
- Med tx = not great results
Dx? Ptosis, miosis, enophthalmos, ispilateral facial sweating, regional hyperthermia, congested MM
Horner’s syndrome - often due ear or guttural pouch infections
