Lecture 16: Respiratory 1 Flashcards
What are the 3 parts that make up the respiratory system?
Conducting airway
Transitional airway
Exchange airway
What are the notable gross and histologic features of the conducting airway?
It is made up of the trachea and bronchi
Containing stratified squamous epithelium along with respiratory epithelium: pseudostratified columnar epithelium with cilia and goblet cells
Contains olfactory epithelium
What are the notable gross and histologic features of the transitional airway?
Made of bronchioles and respiratory bronchioles
There is decreasing amounts of cartilage and there is no cartilage in the bronchioles
They contain club cells: used for detoxification of xenobiotics via oxidases, they make a protective secretion and make surfactant
What are the notable gross and histologic features of the exchange airway?
Alveoli
type 1 pneumocytes are flat and cover 95% of the alveoli. They cannot do cell division
type 2 pneumocytes are found in the same number as type 1 but they only cover 5% of the area. They are cuboidal cells and make type 1 pneumocytes and surfactant
Contain alveolar macrophages
Compare and contrast the below features in bronchi and bronchioles:
- cartilage
- glands
- goblet cells
- cilia
- mucociliary apparatus
- club cells
Bronchi have cartilage and bronchioles dont
bronchi have glands and bronchioles dont
bronchi have goblet cells and bronchioles don’t
bronchi have cilia and bronchioles don’t really (losing them)
bronchi have the mucociliary apparatus and bronchioles don’t
bronchi don’t have club cells but bronchioles do
What are the important anatomic features of the upper respiratory system
The cochae/nasal turbinates are contained in the nasal cavity
- they function to warm/moisten/slow air
The conchae is the communication between the oropharynx and the nasal cavity
- it is not present in horses (obligate nasal breathers)
Additional structures
- nares
- pharynx
- larynx
- trachea
- nasal sinuses
- pharyngeal diverticulum in pigs
- air sacs/laryngeal ventricles in birds and some mammals
List the functions of the respiratory system:
condition air (warm/cool/moisten/filter)
olfaction
immune defence
vocalization
detoxification via club cells
acid-base balance
blood pressure
hormone and enzyme synthesis
leukotriene metabolism
epinephrine and vasoactive amine uptake
List the barriers that oxygen travels through from the alveoli into the capillary:
surfactant
type 1 pneumocyte
basal lamina/basement membrane of the pneumocyte
interstitial connective tissue
endothelial cell basement membrane
endothelial cell
What are the defence mechanisms of the upper resp system
epithelial layers
mucociliary clearance
normal microflora
phagocytosis
tonsils/BALT/MALT
surfactant and antioxidants
What are some factors that can impair the defence mechanisms of the upper resp system
viral infection
immunodeficiency
stress
dehydration
pulmonary edema
uremia
toxic or irritating gases
What is choanal atresia
It is the lack of an opening between the nasal passages and the oropharynx
It can occur either bilaterally or unilaterally
It is also usually accompanied by other malformations
What species is choanal atresia most common in and what are the clinical signs?
camelids
respiratory distress or aspiration pneumonia
What are the primary congenital conditions associated with brachycephalic airway syndrome
elongated soft palate
stenotic nares
hypoplastic trachea/larynx
What are the secondary effects of brachycephalic airway syndrome
everted laryngeal saccules and tonsils
hypertrophied and folded pharyngeal mucosa
laryngeal edema and collapse/tracheal collapse
What animals does tracheal collapse target most commonly?
middle age small breed dogs
like yorkies
What is the pathologic mechanism of tracheal collapse
It is a cartilage defect
The cartilage forms a shallow D shape - it is arced
It flattens dorsoventrally
What are the clinical signs associated with tracheal collapse
honking cough
exercise intolerance
worsened by heat, exercise, and obesity
What species is hypoplastic epiglottis most common in
horses
What are the clinical signs of hypoplastic epiglottis
dorsal displacement of the soft palate
resulting in increased respiratory noise and reduced performance
due to a small epiglottis
What animals are progressive ethmoid hematoma’s most common in
older thoroughbred horses or arabians
What is the pathogenesis of progressive ethmoid hematomas
unknown
maybe a vasoproliferative response
What animals are nasopharyngeal polyps most common in
cats 1-3 yo
horses (nasal mucosa)
reoccurrence is common
What are the clinical signs of nasopharyngeal polyps and how do they relate to the development of the condition
usually occur in the mid ear or auditory tube
if in nose = sneeze
if in mid ear = ataxia/facial nerve paralysis/ horners syndrome
if in pharynx = gagging / dyspnea / dysphagia
What is the pathogenesis of equine laryngeal paralysis
idiopathic
Usually occurs on the left side but can also be bilateral
- maybe because the left recurrent laryngeal nerve is longer but still unknown
if it is bilateral there is probably a systemic cause
What are the clinical signs of equine laryngeal paralysis
Usually occurs on the left side but can also be bilateral
- maybe because the left recurrent laryngeal nerve is longer but still unknown
degeneration and atrophy of the cricoarethynoid muscle
What type of dog usually gets canine laryngeal paralysis
older male dogs
giant or large breeds
What is the pathogenesis of canine laryngeal paralysis
It is secondary to a systemic problem like a neuromuscular disorder
- myesthenia gravis
- hypothyroidism
- anesthesia
It is due to degeneration of the muscle and nerve damage
How does canine laryngeal paralysis present anatomically
bilaterally symmetrical
Compare equine and canine laryngeal paralysis
Equine
- usually the left side
- unknown pathogenesis
Canine
- usually bilateral
- secondary to neuromuscular disease
Why might laryngeal an/or tracheal edema occur
It is edema inside the tissue
It is secondary to acute inflammation
- anaphylaxis
- cattle with atypical interstitial pneumonia
- edema disease in pigs
What is honkers syndrome and waht is its pathogenesis
tracheal edema and hemorrhage syndrome
It affects the dorsal and distal trachea
It occurs secondary to increased intra-tracheal pressure from coughing. This causes mechanical injury and inflammation resulting in increased irritation breathing
What animals commonly get tracheal edema and hemorrhage syndrome?
cattle
Usually in the feedlot during the summer time or with increased exercise
Define rhinitis
inflammation of the mucus membranes of the nose
Define sinusitis
inflammation of the sinuses
Describe 5 types of inflammation
serous: clear fluid
catarrhal: red with fluid and mucus
purulent/suppurative: red with cloudy fluid
- Boston cream donut
- high neutrophils
fibrinous: fluid with ulceration and a pseudomembrane formed
- runny scrambled egg
- neutrophils, debris, and fibrin
granulomatous: caseous
- macrophages, lymphocytes, plasma cells
What is the causative agent of inclusion body rhinitis
suid herpes virus 2
aka cytalomegalovirus
an opportunistic pathogen
What animals does inclusion body rhinitis target
2 -5 week old pigs
What are the clinical signs and consequences of inclusion body rhinitis
catarrhal rhinitis with large cells containing viral inclusion bodies
increased risk for secondary infection
increased morbidity and low mortality
What is the causative agent of infectious bovine rhinotracheitis
bovine herpesvirus 1
How is infectious bovine rhinotracheitis transmitted
aerosol
What are the clinical signs of infectious bovine rhinotracheitis
fever
anorexia
tachypnea
mucopurulent discharge
dyspnea
mucosal hyperemia
What are the gross and histologic lesions associated with infectious bovine rhinotracheitis
Grossly there are erosions and ulcers of the trachea/larynx/nasal cavity
There will also be hyperemia and pustules and petechiae with a fibronecrotic membrane
Histologically there will be eosinophilic intranuclear inclusions with lymphocytes and neutrophils
What are 2 common differentials for infectious bovine rhinotracheitis
Aspiration of chemical irritants like stomach acid
bovine parainfluenza 3
What are 3 causative agents of feline upper respiratory infection
feline herpesvirus 1/alphaherpesvirus
feline calcivirus
chalmydiophilia felia
What animals are most targeted by feline herpesvirus 1
young cats
What is the clinical signs associated with feline herpesvirus 1
fever
oculonasal discharge
ocular involvement
sneeze and cough
rarely it can cause systemic disease
What are the gross lesions associated with feline herpesvirus 1
It causes eye/nose crusting and erosions in the nasal mucosa
rarely it can cause tongue ulcers
How is feline herpesvirus 1 virus diagnosed
Using PCR or virus isolation techniques
What are the clinical signs associated with feline calcivirus
oral ulceration (unlike feline herpesvirus 1)
eye and nose discharge and conjunctivitis
rarely it can cause virulent and systemic disease but if it does it is fatal and very contagious in kittens
- cutaneous edema and ulcers
What is unique about chlamydia as a cause of feline upper resp infection
it is a bacteria
the other causes are viruses (herpes and cacivirus)
What are the clinical signs associated with chlamydiophilia felis
chlamydiosis and chlamydial conjunctivitis
mucopurulent rhinitis
What animal does atopic rhinits target
6 - 12 week old pigs
What is the causative agents of atopic rhinitis
depends on if its progressive or non-progressive
non- progressive = Bordatella bronchiseptica
progressive = Pasturella multocida type D (produce toxin that allows colonization)
- can have a coinfection with B. bronchiseptica that produces a dermonecrotic toxin which reduces bone formation and increases bone resorption
What are the clinical signs of non-progressive atopic rhinitis
mild sneezing and nasal discharge
this is of low significance
What are the clinical signs of progressive atopic rhinitis
snout distortion and malformation and atrophy of nasal turbinates
What are the gross and histologic findings associated with atopic rhinitis
Grossly if you section the head behind the 1st and 2nd premolars you see the snout/turbinate distortion
histologically it results in hyperplasia of osteoclasts
How is atopic rhinitis diagnosed
nasal swabs: you must culture both B. bronchiseptica and P. multocida
PCR or ELISA to detect the toxin
What is the causative agent of equine strangles
Streptococcus equi equi
What animals does equine strangles target
young horses
as they age they develop resistance
What is a top differential for equine strangles?
Streptococcus equi zooepidemicus
This is because it causes similar clinical disease
But it is commensal (S. equi equi is not commensal)
What are the clinical manifestations of equine strangles
It causes lymph node abscesses - either submandibular or retropharyngeal
20% will have more complications
- guttoral pouch empyema (inflammation can damage nerves and cause horners syndrome)
- pneumonia
- bastard strangles
- purpura hemorrhagic and vasculitis
What does Aspergillus fumigatus look like and where is it found
normal in the environment
Looks yellow green or black fungi
What are the clinical manifestations of Aspergillus fumigatus? How does it differ by species
It causes suppurative, caseous, or hemorrhagic rhinits
dogs: turbinate lysis. and remodelling
horses: guttoral pouch mycosis and vascular erosion
What are 3 causes of fungal rhinitis
Aspergillus fumigatus
Cryptococcus (neoformans or gatti)
Rhinosporidiosis
What are the species of Cryptococcus that cause fungal rhinitis
C. neorformans
C. gatti
What animals does Cryptococcus target to cause fungal rhinitis
cats mainly
dogs, horses, small ruminants, cattle, birds
it is zoonotic
What are the clinical signs of cryptococcus-associated rhinitis
nasal discharge and facial swelling
What are the histologic signs of cryptococcus-associated rhinitis
thick capsule with narrow based budding
What is the causative species of Rhinosporidiosis-caused rhinitis
R. seeberi
What animal does Rhinosporidiosis target
dogs mainly
Usually found in wet and tropical areas
What are the gross signs associated with Rhinosporidiosis
single unilateral nasal polyp
What is the pathogenesis os Oestrus ovis
The sheep bot fly lays eggs on the nares and they climb into the nose and get stick in the sinuses and turbinates
What are the clinical signs of Oestrus ovis infestation
fecal irritation and sneezing
if it is very severe there can be secondary infection or inflammation of the brain or meninges
What animal does Filaroides osteri target
dogs both wild and domestic
What is the pathogenesis of Filaroides osteri
It forms nodules at the tracheal bifurcation
The 5-15mm meta strongyle eggs are coughed up and swallowed
What is the clinical manifestation of Filaroides osteri infestation
there is very little clinical disease - if it is severe it can cause a chronic cough
Describe 3 types of guttoral pouch disease and what causes them
mycosis: Aspergillus
empyeme: Streptococcus
tympany: often in young horses due to impairment of the valvular action of the nasopharyngeal orifice
What are the clinical consequences of guttoral pouch disease
exsanguination
laryngeal paralysis and/or facial paralysis
horners syndrome
List the common primary neoplasms of the small animal upper respiratory system in order from most common to least
- carcinoma - many types
- dogs = adenocarcinoma
- cat SCC - chondrosarcoma
- fibrosarcoma
- osteosarcoma
cats commonly get lymphoma (B cell origin with lymphoplasmacytic inflammation and FeLV positive)
What are the common primary neoplasias of horses
paranasal sinsus tumors are more likely
carcinomas - SCC
What is the enzootic nasal tumor caused by and what animals is it common in
Caused by enzootic nasal tumor virus which is a betaretrovirus
type 1 targets sheep
type 2 targets goats
What is the effect of enzootic nasal tumor virus
causes adenoma development (more common than adenocarcinoma development)
in the ethmoid turbinates
It rarely metastasizes but is locally aggressive
What are 3 factors that make the respiratory system vulnerable to insults
lots of alveoli surface/exposure
high volume of airflow
high concentration of noxious elements in the air
What are the defence mechanisms specific to the conducting airway
mucociliary clearance
- mucus
coughing/sneezing
antibodies and lysozyme
What are the defence mechanisms specific to the transitional airway
club cells
antioxidants
lysozyme
antibodies
What are the defence mechanisms specific to the exchange airway
alveolar macrophages
intravascular macrophages
opsonizing antibodies
antioxidants
surfactant
What are routes of entry pathogens can take to infect the respiratory system
aerogenous/inhale: virus/fungi/bacteria/gas/pneumotoxicants
hematogenous: virus/fungi/bacteria/parasite/toxins/pneumotoxicants
direct: wound, foreign body, bite, ruptured esophagus or diaphragm
other insults include lung edema, dehydration, stress, uremia (amonia), immunodeficiency
