Lower Airway Diseases in Small Animals

Question 1

Coughing Puppy Rule outs…

Answer 1

• Canine infectious tracheo-bronchitis > “Kennel cough”
• Tracheal foreign body
• Tracheal collapse
  > Cons: usually older, seasonal
• Bronchopneumonia
  > Cons: usually anorexia, lethargy, history of aspiration or exposure

Question 2

Canine Infectious Tracheobronchitis
- what is this?

Answer 2

Infectious “complex”
* Bordetella bronchiseptica
* Canine adenovirus-2
* Canine parainfluenza virus
* Canine respiratory coronavirus
* +/- other secondary organisms

Question 3

Canine Infectious Tracheobronchitis
- spread?
- disease course?

Answer 3

• Highly contagious
  > Usually, history of contact with other dogs
• Usually mild & self-limiting (within 1-2 weeks)
  > frustrating for client as dog is continuously coughing and may not be able to sleep

Question 4

Canine Infectious Tracheobronchitis
* Clinical features

Answer 4

• Dry, hacking, paroxysmal cough most common sign
• May have nasal discharge (purulent)
• Usually healthy otherwise

Question 5

Diagnosing ITB

Answer 5

• Diagnosis usually presumptive
  > History & clinical signs
  <><>
  Thoracic auscultation, radiographs, CBC
• Usually normal
• Diagnostic tests beyond the physical examination usually not performed in routine cases
  > Coughing induced on tracheal palpation

Question 6

Treating ITB

Answer 6

• Antibiotics have limited benefit in uncomplicated cases
  > Course of infection not shortened
  > Self-limiting disease
  <><><><>
• Antibiotics rarely used
• Antibiotics warranted only if:
• Systemic signs or deeper respiratory involvement
  > E.g., fever, productive cough
• Or if neonates (<8 weeks)
• Empirical choices include Clavamox, doxycycline
  <><><><>
  Antivirals?
• Not recommended
  <><><><>
  Glucocorticoids?
• Not recommended
• Does not shorten course of disease
• May worsen illness if high dose used (immunosuppression)
  <><><><>
  Antitussives for dogs with dry cough
• Hydrocodone, butorphanol
• Contraindicated in cases of productive cough, systemic signs that may be reflective of pneumonia
  <><><><>
  Bronchodilators can help decrease bronchospasm

Question 7

Treating ITB Antitussives
- which ones?
- what is their use?
- when not to use?

Answer 7

Antitussives for dogs with dry cough
* Hydrocodone, butorphanol
* Contraindicated in cases of productive cough, systemic signs that may be reflective of pneumonia
<><><><>
not recommended
- cough is cleaning the lungs, if we give this we can make things worse
- can give for the night if the puppy os not able to sleep, for example

Question 8

ITB Prevention

Answer 8

• B. bronchiseptica & Parainfluenza vaccine
• ± Adenovirus
• Recommended for at-risk dogs
• Often required for boarding kennels
• May lessen severity or prevent infections

Question 9

ITB Prognosis

Answer 9

• Excellent prognosis for recovery in uncomplicated cases

Question 10

Complicated ITB
- what is this?
- what should we do?

Answer 10

• Persisting (>1-2 weeks) or progressive clinical signs warrant the following diagnostics:
• Thoracic radiographs
• Airway sampling (transtracheal wash)
• CBC
• ± infectious disease testing (e.g., canine influenza)
  <><><><>
• Pneumonia can result from ITB and requires further therapy

Question 11

what radiographs do we need to diagnose tracheal collapse?

Answer 11

we need both inspiratory and expiratory views to see tracheal collapse - some are more visible in one view or the other

Question 12

Tracheal Collapse, origins

Answer 12

• Tracheal cartilage malacia
  > Dorsoventral collapse
• Miniature and toy breeds
  > Yorkshire Terrier and Pomeranian

Question 13

Clinical Signs of tracheal collapse

Answer 13

• “Goose – honk” cough!!
• Wheezing
• Hacking
• Exercise intolerance
• Cyanosis +/- syncope

Question 14

tracheal collapse dx? types and how to differentiate?

Answer 14

Radiography
* Dynamic condition
* Not overly sensitive
<><>
* Inspiration > cervical collapse
* Expiration > thoracic collapse
<><>
* also, fluoroscopy

Question 15

Medical Management for tracheal collapse (broad, no drug names)

Answer 15

Initially
* Weight loss
* Environmental modifications
> Harness vs neck collar
> Removal of secondhand smoke
> Normal humidity
> Dental prophylaxis
* Pharmaceutical therapy

Question 16

drugs we use for medical management of tracheal collapse

Answer 16

• Doxycycline for a week > when severe signs, also has antiinflammatory properties
• Corticosteroids > reduce inflammation
• Bronchodilators > Open small airways and anti-inflammatory effect
• Anti-tussives
• Tracheal collapse elixir (0.22-0.44 ml/kg q8hr)
  > Phenobarbital, isoproterenol, theophylline, ephedrine

Question 17

possible issue with bronchodilators for tracheal collapse

Answer 17

questionable, as it can increase negative pressure > collapse

Question 18

Medical Management for tracheal collapse efficacy? when to go to surgery?

Answer 18

• Majority of dogs respond well
  to medical management
• However… progressive disease and still guarded long- term prognosis
• Surgery/stent is palliative, performed when medical treatment fails

Question 19

Extra-luminal Tracheal Prosthesis - what is this? disadvantages?

Answer 19

• External rings around trachea
  <><>
• Disadvantages:
• Only for cervical collapse
• Collapse can occur beyond rings
• 40% complication rate

Question 20

Endo-Luminal Tracheal Stent - when do we use this? what is it? complications?

Answer 20

more common, generally better
> for cases that are not improving with medical manamgement
<><><><>
* Minimally-invasive insertion
> Fluoroscopy +/- scoping
<><>
* Complications:
* Stent migration or fracture
* Granulation tissue formation
* Progressive collapse
* Costly

Question 21

Endo-Luminal Tracheal Stent - at what point should we consider this treatment? goal? results? what else do we need?

Answer 21

• LAST RESORT ONLY
• Goal: allow breathing and better quality of life
• Dogs won’t stop coughing !!!!!
• 100% need medical management

Question 22

Tracheal Collapse Prognosis

Answer 22

• Life-long condition, progressive
• Depends on grade of collapse
• More severe collapse = guarded prognosis

Question 23

Bacterial Pneumonia Predisposing causes

Answer 23

Aspiration of GI contents
* Megaesophagus, recent anesthesia, chronic vomiting, seizures, force feeding, dysphagia, etc
<><>
Systemic immunosuppression
* Drugs
* Endocrine dz (hyperadrenocorticism, diabetes mellitus)
* Infection (FeLV, FIV)
<><>
Defective respiratory defenses/damage to
respiratory epithelium
* Bronchiectasia
* Smoke inhalation
<><>
* Sepsis (hematogenous spread of bacteria)

Question 24

Aspiration Pneumonia - pathogenesis?

Answer 24

• Low bacterial content of aspirated GI material
• Gastric pH kills most bacteria – contents may
  be sterile
• Material may be contaminated by oral bacteria
  <><><><>
• Acid injury to pulmonary parenchyma
• Induces lung inflammation, bronchoconstriction
• Predisposes to secondary (opportunistic) bacterial invaders

Question 25

**Aspiration and bacterial pneumonia share several historical & PE findings, and may include:**

Answer 25

* **Anorexia * Lethargy** * Exercise intolerance * Tachypnea * Cough (more than 50% do not cough)!!! * Dyspnea * Cyanosis if severe lung involvement * Fever * Nasal discharge * Inspiratory crackles * Increased bronchovesicular sounds

Question 26

Pneumonia Thoracic Radiographs

Answer 26

* Interstitial to alveolar radiographic pattern common * Typical distribution is ventral * May only affect one lung lobe > Often right middle lung lobe with aspiration pneumonia > Right cranial or caudal portion of left cranial

Question 27

Pneumonia CBC and pulse ox diagnostics?

Answer 27

* CBC – neutrophilia common * Hypoxemia common > Pulse oximetry, blood gas analysis > Depends on how much lung is affected

Question 28

Airway Sampling for pneumonia use? * Most common bacterial pathogens in canine pneumonia:

Answer 28

* Culture & sensitivity helpful in guiding treatment <><><><> Most common bacterial pathogens in canine pneumonia: * E. coli * Pasteurella spp. * Bordetella bronchiseptica (especially in young dogs) * Streptococcus spp. * Staphylococcus spp.

Question 29

Empirical Antibiotic Selection for pneumonia? mild vs severe cases

Answer 29

Dogs with mild to moderate clinical signs: * Ampicillin, amoxicillin, amoxicillin-clavulanic acid * Cephalexin, cefazolin <><> Dogs with severe clinical signs or sepsis: * IV route * Add a fluoroquinolone or aminoglycoside

Question 30

pneumonia treatment, other than antibiotics

Answer 30

* Oxygen support (nasal canula) * Maintain adequate airway hydration > IV fluids, nebulization with saline and coupage

Question 31

should we monitor pneumonia with radiographs? what should we do? how long should we treat?

Answer 31

* Paradigm shift in monitoring resolution: skip the x-rays, consider C-Reactive Protein to monitor resolution * Shortest course of antimicrobials <><><><> * Recurrent pneumonia is challenging * Underlying causes often hard to treat

Question 32

pneumonia prognosis? how can radiographs predict?

Answer 32

Prognosis for recovery is good * Depends on underlying cause * Relapse may occur if underlying cause not able to be corrected <><><><> * Severity of radiographic involvement does not appear to predict prognosis

Question 33

what should we do if there is pneumonia recurrence?

Answer 33

CT-scanner recommended to look for FB