Pathology of Larynx, Trachea, Bronchi, & Bronchioles (URT) Flashcards
What are some overlapping clinical signs of rhinitis and neoplastic dz of the URT?
- Uni/bilateral nasal d/c
- Epistaxis
- Sneezing
- Air-flow obstruction
- Facial Deformity
- Encrustation of tears at medial canthus (secondary to obstruction of nasolacrimal duct)
What are the various types of rhinitis?
- Serous
- Catarrhal
- Purulent
- Fibrinous/fibrino-necrotic
- Granulomatous
Infectious Rhinitis follows upset in…
normal nasal microbial flora
AKA Dysbiosis
Describe serous exudate
Clear, thin, few cells
Produced by serous glands in submucosa
What causes serous exudate?
- Mild irritants/cold air
- Early viral infections
- Mild allergic rxns
Describe catarrhal exudate
Thick, viscous, abundant mucus
Tenacious, sticky
What is unique about catarrhal exudate compared w/ serous exudate?
It has increased goblet cell activity & submucosal glands
Describe purulent exudate
Thick, opaque
White, green, brown in colour
Fibrinous/Fibrinonecrotic inflammation
Necrosis of a well-vascularised epithelial surface
Fibronecrotic (diphtheritic) membrane
exudation of abundant plasma fibrinogen
Aspiration of exudate into lungs & no mucus escalator to remove
Granulomatous Rhinitis
infiltration of mucosa/submucosa by macrophage-rich inflammation
Granulomatous rhinitis occurs in response to…
- Fungi
- Foreign material
What are some adverse sequelae of rhinitis?
- Pneumonia
- Sinusitis
- Miningitis
What are some specific conditions originating as rhinitis?
- Porcine atrophic rhinitis
- Progressive Ethmoid Haematoma
The majority of tumours of the URT are…
Malignant
Primary tumours of the URT are of what types of tissues?
- Epithelium/glands
- Mesenchymal tissue
- Lymphoid tissue
Sinusitis and rhinitis often follow…
*Periodontitis
*Dehorning
*Haematogenous spread
What are some sequelae of sinusitis?
*facial deformity
*meningitis
What is a sinus mucocoele and in what condition does it occur?
Retention of normal seromucinous secretion that blocks drainage.
Occurs w/ sinusitis
What is a sinus pyocoele and when does it occur?
AKA empyema
Purulent exudate in an enclosed activity
Occurs in the sinuses if a secondary bacterial infection is present
What important structures are near the guttural pouch?
*Pharyngeal branch of the Vagus n. (X)
*Pharyngeal branch of the glossopharyngeal n. (IX)
*Internal carotid a.
*Hypoglossal n. (XII)
*External carotid a.
*Facial n. (VII)
How does aspergillus get into the guttural pouch?
Aspergillus spores are inhaled from moldy hay/straw
Aspergillus spores can lead to
diphtheritic plaques on the dorsal & medial pouch mucosa
Vasculitis within the guttural pouch can lead to…
epistaxis
Neuritis/neuropathy of the glossopharyngeal & vagus nerves can lead to…
pharyngeal paralysis/dysphagia
Neuritis/neuropathy of fibres of recurrent laryngeal n. while still w/i parent vagus n. can lead to…
laryngeal hemiplegia/’roaring’
Guttural pouch mycoses can lead to what?
an empyema within the pouch
Any obstruction of the rima glottidis can lead to…
possible respiratory distress & noise at rest or after exercise
Laryngeal obstruction can lead to…
sudden death
What occurs with laryngeal edema?
Mucosa thickens leading to obstruction of the lumen
laryngeal edema can result from…
trauma, local inflammation, smoke inhalation, some allergic rxns
Describe how laryngeal hemiplegia in horses causes roaring.
Neurogenic of atrophy of the left cricoarytenoideus causes the left arytenoid cartilage & vocal fold flop into the lumen on inspiration causing roaring on inspiration during exercise due to the obstruction of airflow & abnormal vibration of vocal cords
Laryngeal hemiplegia can have idiopathic degeneration of large myelinated fibres of the laryngeal nerve. This is known as what medical term?
Neuropathy
Why are the axons of the LRL n. more susceptible to injury?
*Size and conformation of the horse can stretch/damage the n. b/c constrained around the aortic arch
*compression of LR laryngeal n. due to enlarged & inflamed retropharyngeal LN
*damage to nerve secondary to guttural pouch mycosis
Axons of the LRL nerve are longer than that of the RRL n. and are more common in
males & animals >16 hands
What breeds/species & sex are affected by laryngeal chondritis?
*Thoroughbred horses
*Belgian Blue cattle
*Texel sheep
*Typically young males affected
What is the etiology of laryngeal chondritis?
*trauma
*conformation
During laryngeal chondritis, the mucosa swells & may even contain…
necrotic sinus tracts
Tracheal hypoplasia is commonly seen in what breed?
Young bulldogs as part of BOAS
What occurs during tracheal hypoplasia?
*The tracheal luminal cross-sectional area is decreased
*cartilaginous rings overlap
Why do cartilaginous rings overlap in tracheal hypoplasia?
High negative pressures are created by increased respiratory efforts as the frictional resistance to air flow in the URT is large in bulldogs
What breeds/species/age are most commonly affected by collapsing trachea?
*Middle-ages small breeds
*Yorkies, Pomeranians, Poodles
*Shetland Ponies
Describe collapsing trachea.
Tracheal rings become less rigid and collapse with the stretching of the dorsalis m.
What is tracheal stenosis and in what condition does it occur?
*Progressive, chronic ‘goose honk’-type cough
*Occurs in collapsing trachea
What type of inflammation is tracheitis?
fibrinonecrotic/diphtheritic Inflammation
Tracheitis can further be divided into…
inflammation of multiple locations of the trachea and surrounding regions
Aka tracheobronchitis, laryngotracheitis, rhinotracheitis
What occurs in tracheitis?
Viral damages ciliated epithelium causing local swelling & stenosis. This leads to aspiration of debris, and secondary bacterial infection
What causes bronchitis/bronchiolitis?
it is a reaction to injury similar to nasal/tracheal mucosa
Bronchitis/Bronchiolitis results in…
*Cough
*wheezing due to airway obstruction
*impairment of lung defenses
Airway obstruction in bronchitis/bronchiolitis is notable in diffuse bronchiolitis & causes…
*increased expiratory effort/
dyspnea
Airway obstruction in diffuse bronchiolitis is exacerbated by
the slight collapse in cross-sectional area during expiration
Bronchitis/bronchiolitis is classified based on…
exudate involved
*catarrhal
*purulent
*fibrinous
*fibrino-necrotic
*granulomatous
What are some viral etiologies of bronchitis/bronchiolitis?
*Horses - Rhino, influenza, herpes
*cattle - IBR
*pigs - influenza
*dogs - Kennel C (CDV< PI-2, CAV-2, CHV)
What bacterial, parasitic, and allergic etiologies of bronchitis/bronchiolitis exist?
*Bacterial: Bordetella sp.
*Parasitic: Dictyocaulus sp., Oslerus osleri
*Allergic: equine/feline asthma
What changes occur when bronchitis/bronchiolitis becomes chronic?
*Mucus metaplasia (goblet cell hyperplasia)
*squamous metaplasia
*bronchiolitis obliterans
*bronchiectasis
*bronchostenosis
What specific conditions affect the bronchi/bronchioles?
*Chronic bronchitis in dogs
*feline asthma
What breeds/age are affected by chronic bronchitis in dogs?
*older, obese small & toy breeds
Chronic bronchitis in dogs may be related to…
*concurrent chronic LSHF
*thicker than normal mucus blanket
*atelectasis
Feline asthma is caused by…
bronchitis & reversible airway hyperreactivity
Feline asthma often has…
recurrent bouts of cough & wheezing
Feline asthma has what type of hypersensitivity response? What does it react to?
type 1 in response to inhaled allergens
Feline asthma on radiographs has what pattern?
bronchial pattern showing thickening of bronchial-bronchiolar walls which looks like ring-like radiopacities (‘doughnuts’)
