Pathology of The Respiratory System – Part 1 Flashcards
In general the upper respiratory tract is the portion of the respiratory system located _______ the thoracic cavity.
Everything cranial to _______ _____ is the UR
outside, thoracic inlet
Physiologically the respiratory tract is divided into three continuous systems:
Conducting, transitional and exchange system
- What does the conducting system include?
- The mucosa of this system is primarily lined with?
- What do the nasal turbinates/conchae have?
- Includes the nasal cavity, paranasal sinuses,
larynx, trachea and bronchi. - The mucosa of this system is primarily lined by pseudostratified columnar ciliated epithelium and goblet cells.
- Nasal turbinates/conchae have spiral shape to increase surface, warm up and humidify inspirated air.
- What does the transitional system include?
- The mucosa of this system is primarily lined with?
- What do the nasal turbinates/conchae have?
2.- Transitional system : consists exclusively of bronchioles which are
lined by non-ciliated secretory cells: Club cells (formerly Clara cells) important in the detoxification of xenobiotics, and only a few ciliated cells. Healthy bronchioles do not have goblet cells. Goblet cells important in resp epithelium and are located in upper respiratory system
- What does the exchange system include?
- The mucosa of this system is primarily lined with?
- What do the nasal turbinates/conchae have?
- Exchange system: Composed of alveolar ducts and millions of alveoli;
thin-walled structures enveloped by a rich network of capillaries, the
pulmonary capillaries. Alveoli are lined by epithelial type I (membranous)
and type II (granular) pneumocytes (also called pneumonocytes).
Alveoli is where gas exchange occurs.
Each of these 3 systems has a characteristic susceptibility to _______ and specific type of ____ response and _____.
injury, host, repair
Describe the blood supply in the lungs.
The lungs have a dual blood supply: Through the pulmonary arteries which conduct deoxygenated blood from the right side of the heart, and the bronchial arteries, which carry oxygenated blood.
In cases of infarction in the longs, collateral circulation is good which is why the lungs are less susceptible to infarction
In addition to gas exchange, the respiratory system is
also involved in ?
phonation, olfaction, temperature
regulation, acid–base balance, blood pressure
regulation etc.
Label this image accordingly.
Nasal cavity: pseudostra, ciliated, column epi
pseudo, column is very thick in the back of the olfactory region
nares are lined by Strati squammy so tumors could be squamo0us cell carcinoma due ot tissue type. Review different tissue types
mucociliary escalator present in epithelium: mucous traps pathogens towards pharynx where secretions are swallowed and don’t enter LR tract.
What pneumocytes are present on the surface? of the alveoli?
Type 1 more numerous, more susceptible to injury; first ones to undergo degeneration or die.
Type 2 = more cuboidal and produce surfactants and prevent collapse of airways. Can replicate in alveolar wall and convert into type 1 pneumocytes in case of lung injury
Where can you find normal flora in the respiratory tract?
Normal Flora – Restricted only to the most
proximal region of the conductive system:
nasal cavity, nasopharynx, larynx and trachea.
The distal portions of the respiratory tract are
considered to be sterile
T/F: Even though the majority of the organisms of the normal respiratory flora are harmless others are potentially pathogenic; e.g.: Mannheimia haemolytica, Bordetella bronchiseptica.
True
“The air that we inhale every day
in a healthy environment
contains billions of suspended
particles, spores, bacteria,
viruses and noxious gases that
are constantly carried deep into
the lungs”…Fortunately the
lungs have a very efficient
defense system to deal with the
environmental hazards present
under normal conditions
What are the non-specific defense mechanisms of the respiratory system?
Non-specific (non immune-mediated):
Mucous trapping
- eliminated by escalator
- heavy smokers can develop metaplasia of trachea and bronchi, losing normal epithelium –> strati squammy epi which does not have this function and instead are coughing and sneezing –> more susceptible to develop disease.
Mucociliary clearance (mucociliary escalator)
Phagocytosis
Air turbulence (generated by coughing and sneezing)
What are the specific defense mechanisms of the respiratory system?
Specific (immune-mediated):
Antibody production
Antibody-mediated phagocytosis
Cell-mediated immunity
PAMS found in lungs.
This is a terminal bronchiole with type 1 and type 2 pneumocytes.
May see a few PAMs in this area normally. Function = if there is any particulate materials here, PAMs move via escalator and eliminate.
What are PIMs
Intravascular
Macrophages (“PIMs”,
present in ruminants, cats, pigs and
horses)
Get rid of circulating pathogens in the blood. Attach to wall of bronchioles?
Do we have PIMs?
No
In dogs, humans and laboratory rodents the cells responsible for removing circulating bacteria and other particles from blood are the Kupffer cells (liver) and splenic macrophages.
What can be seen in the image below?
PAM
Black circles = lysosomes.
Contain proteolytic enzymes that destroy organisms
Animals suffering from a respiratory viral infection
have ?
notably suppressed defense mechanisms which make them
susceptible to bacterial colonization within the airways
Viruses are not the only factor known to predispose to bacterial pneumonia, other causes are:
Stress
Dehydration
Pulmonary edema
Uremia
Ammonia
Immunosuppression/ immunodeficiency
How do you conduct a post-mortem exam of the respiratory tract?
Thorough systematic examination and appropriate sampling are very
important. Microbiology results should always be interpreted
carefully taken into account clinical and post-mortem findings.
Pig, normal lungs
Pink, pliable moist
Nasal cavity
sagital sectioning of head
Is there any nasal discharge? Is it serous? Mucosuppurative? Etc.
Gray —> lymphoid tissue = normal
Ethmoidal hematoma – cause of epistaxis in old horses
Pedunculated tumor-like lesion in older horses. The exact etiology of this lesion is unknown. Results in
often unilateral nasal bleeding
usually attached to nasal turbinates.
Perform endoscopy
Ethmoidal hematoma
Fibrinous rhinitis – mid-sagittal section of the
head – Calf with IBR
Infectious Bovine Rhinotracheitis (formation of
diphtheritic membrane)
rhinitis = inflammation in nasal cavity
Young cattle with history of resp disease; fibrinous exudate that forms a pseudomembrane with areas of ulceation. This type of rhiibites is associated with IB. CAn be seen in larynx and trachea as well.
Fibrino necrotizing rhinitis
Mucosupurative exudate
Mucosa is very red due ot heorrhage
Mucosupurative hemorrhagic rhinitis
Ex. of rhinitis in sheep
Oestrus ovis infection
present all over world, esp in more dry places in the south.
Fly larvae deposit eggs in nares. Grow and form these bots producing irritation and rhinitis. Mucosuppurative nasal discharge. Crawling in nasal turbinates, animal is restless and loss of appetite. Bots can enter foramina that communicates between nasal cavity and sinuses. Can grow in foramina and can’t exit.
Oestrus ovis, nasal bot in sheep
– worldwide distribution
Rare sequel: Aberrant migration of Oestrus ovis larva, sheep-
Larvae located in nasal cavity can penetrae pinital plate and produce meningoencephalitis
Bot found in bet third and lateral ventricle
Atrophic rhinitis in pigs.
❑ Multifactorial disease in
growing pigs.
❑ Currently is thought to be the result of a combined infection of Bordetella bronchiseptica and
Pasteurella multocida types D
and A.
Can present with nasal discharge, but main is deviation of the snout.
Asymmetric atrophy of nasal turbinates and lateral deviation of nasal septum and deviation of the snout.
Atrophic Rhinitis – UCVM, OI
Top: Normal
Right: Affected pig
More susceptible to developing pneumonia
Atrophic Rhinitis – UCVM, OI
Top: Normal
Right: Affected pig
The toxigenic strains of P. multocida produce _________ which inhibit ________ activity and promote ________ reabsorption of the nasal turbinates. “The _______ scroll of the _________ nasal turbinate is the area most commonly and consistently
affected”… But can affect all turbinates
The toxigenic strains of P. multocida produce cytotoxins which inhibit osteoblastic
activity and promote osteoclastic reabsorption of the nasal turbinates. “The ventral
scroll of the ventral nasal turbinate is the area most commonly and consistently
affected”… But can affect all turbinates
Asymmetric atrophy on top left, severe lat deviation of septum here on bottom left.
Inclusion Body Rhinitis –
Porcine Cytomegalovirus (suid
herpesvirus 2 [SHV-2])
infection, Pig, AVC, OI
Usually in pigs 3-5 weeks of age. Fatal systemic infection occurs occasionally in younger suckling pigs
(less than 3 weeks of age)
Nasal submucosal glands
with large basophilic
Intranuclear inclusions
(SHV-2)
Swine herpesvirus 2 = etiology
Affects pigs around a month of age. Produces sneezing and runny nose.
Cytomegaly = cells become bigger, IN inclusion bodies. Resp. mucosa becomes errosive, ulcerated.
- The cat in this image is suffering from?
- How old are cats that are typically affected by this disease?
- What is one of the main clinical signs?
- What is the prognosis of this condition?
Feline herpesvirus 1 (Feline viral rhinotracheitis [FVR]): rhinitis, conjunctivitis
Kittens, nasal discharge
Transient type of dz
May not do well for a few days bt can recover
Stray, feral kittens, –> immunosuppressed –> pneumonia –> die
The cat in this image is suffering from ______. From this picture, you can see mild ________ discharge in addition to _______ and ________ stomatitis - diffuse interstitial _________ may also occur. This disease is similar to?
Feline Calicivirus (FCV). Mild occulonasal discharge in addition to vesicular and ulcerative stomatitis - diffuse
interstitial pneumonia may also occur.
Similar to FVR
Immunosuppressed –> more severe disease
Cat, vesicles, tongue – Feline calicivirus, Noah’s Arkives
Morphologic Diagnosis?
Cat, feline calicivirus – ulcerative glossitis
Noah’s Arkives
Oral vesicles can ulcerate.
Can be located not only on ventral surface, but on the dorsal surface and tip
Cat, diffuse interstitial pneumonia, FCV
Granulomatous rhinitis, dog due to Rhinosporidium seeberi (rare aquatic protistan parasite; for a long time it was thought to be fungus, but it is no longer classified as such)
Proliferative looking and you may think this is a tumor.
Rhino sporidiosis
Swimming in places down south –> at risk
Mature sporangia filled with endospores
GP is a dilatation of ET
ET = pressure, equalization?
Covered by a thin membrane that can produce problems
Guttural pouch tympany in a foal
Entrapment of air within pouch.
If touch, it isn’t painful. Tympanic sound due to air
Associated with congenital problems in ET.
Some do surgery to repair 9remove air), others leave it alone and resolves on own.
Most of time no clinical signs
Name the condition pictured below.
Strangles, Streptococcus equi, lymph node and guttural pouch
involvement
Can result in rhintiis, infl of gp = eustachitis –> suppurative inflammation
Lesion very painful due to accumulation of pus, submandib LN –> suppurative lymphadenitis (mandibular and parotid LN involved).
Cytokines, proteases, eats at tissue –> draining on skin
Chronic sever lesions that produce eustachitis –> strepto equi. Can culture to see.
Focal areas of __________ representing _______ tracks
Nasal discharge that is primarily _______.
Mixed with _____ sometimes.
Focal areas of ulceration reresenting fistulus tracks
Nasal discharge that is primarily suppurative.
Mixed with blood sometimes.
Inflammation of the guttural pouch, horse (guttural pouch empyema) due to “strangles”-TAMU
“Inspissated” exudate = dry exudate
Hyoid bone in middle holds the tongue?. Once you cut this bone, can remove trachea and ?
Separates lateral and medial compartment?
GP Empyema = when there is a lot of pus
Chronic, suppurative exudate4 looks a bit dr (term?). B/c of movement when animals eatig, this dry exudate starts to look like caritlage; bluish white in color. With time, the exudate smooths itself out.
Internal carotid artery, Cranial nerve 9-11, connection eteen GP and cranil nerve 7, Some cases with strangles –> cranial neuropathies e.g. facial paralysis, paralysis of the tongue.
“Chondroids”
You are called to a horse ranch and on presentation see this. This horse is kept mostly indoors, and in a very humid environment. Based on this information, your preliminary diagnosis is?
Mycotic infection
Horses kept indoors are more suscpetible b/c fungus in environment
Hay gets humid
Damage to internal carotid artery can occur
- Guttural Pouch mycosis is caused by?
- What does this infection involve?
- What artery is typically damaged in this type of infection?
- An infection with Aspergillus fumigatus or other Aspergillus species.
- Involvement of cranial nerves (VII, IX, X, XI, XII) is common and result in a variety of clinical signs.
- Erosion of the wall of the internal carotid artery can lead to epistaxis or fatal hemorrhage
Guttural pouch Mycosis- horse. Mdx?
Multifocal, ulcerative and necrotizing eustachitis
Oxipital condyle on left.
Inside filled with blood
Horse had mycotic eustachitis
A horse suffering from a Mycotic infection will commonly suffer from a lesion in this artery…
Lesion in Internal Carotid artery
- Lumen of artery had huge thrombus containing fungal organism
What can be seen below?
GP filled with fibrinonecrotic material
Mycotic eustachitis
GP filled with blood
Which special stains are often used to visualize fungi within tissue sections?
Guttural pouch mycosis, AVC E24094-97
Which special stains are often used to visualize
fungi within tissue sections?
GMS (Gomori’s methenamine silver) stain and
PAS (Periodic Acid Shiff) stain.
Locally aggressive tumor b/c infiltrate adjacent CT, bone, etc. But they are slow to metastasize. When they do, they go to regional LN. Metastasis is more rare. If they occur, they occur after a long period of time.
Produce a lot of necrosis
Unable to open eye because eye is being pushed back.
Relisten
This is not an inflammatory lesion, it is associated with SCC.
Lesion is necrotizing, ulcerative, proliferative you will see a secondary bacterial infection –> inflammation associated. Invading the periocular tissues and the eyeballs are pushed back slightly. Prolapsed third eyelid.
Early Computed Tomography (CT) Scan
Image
Nasal carcinoma (neoplasia)
Cross section of the head of a dog with a nasal tumor. Clinical presentation is going to be asymmetry of the nose. Also, runny nose and could be unilateral secretions coming from the nares. Mucosuppurative/suppurative lesions; discharge from nose. Occasionally you can see epistaxis associated with a tumor in the nasal cavity. External defamation occurs usually after a while b/c the tumor is growing. Nasal septum deviated to one side due to increased density that represents the nasal tumor.
Clinical history: Dog on presentation was experiencing epistaxis, clear malformation. Owner did not want to run diagnostics. Dog was having difficult breathing (dyspnea) and in the end they euthanized this dog.
Based on this information, what is the etiologic diagnosis?
At what age does this condition typically appear?
- Nasal neoplasia.
- Appears at later stages in life. Younger individuals are more susceptible to develop malignant mesenchymal tumors (that are called sarcomas).
3-year-old German Shepherd mixed dog –Nasal and facial
deformity.
This is an image of?
A Nasal Fibrosarcoma, 3-year-old dog
Complete defacement of the strucutral architecture and integrirty of the nose.
proliferative lesion b/c destroyiong nose.
roof of palette
fibrosrcoma dx.
This image below was taken of a sheep. On presentation, this patient was in respiratory distress. Based on the image, this sheep is probably suffering from? This condition primarily affects which species?
Enzootic nasal carcinoma - Viral induced tumor (oncogenic virus). (or adenocarcinoma), sheep.
Etiology: Enzootic Nasal Tumor virus (ENTV, an ovine beta-retrovirus)
Primarily affects sheep and goats.
Specific location of this tumor in the nasal turbinates (more caudal portion of the turbinates). Grow slowly and primarily by compression. Categorized as slow grade adenocarcinoma. Of epithelial origin. Considered low grade b/c do not produce excessive destruction of CT. Damage adjacent tissues a bit, but primarily destruction by compression. Don’t ever metastasize.
Benign –> grow by expansion and pushing tissues around
Malignant —> grow by infiltration
Give a morphologic and etiologic dx based on this image of a calf below.
- Necrotic laryngitis (Calf diphtheria); Secondary infection by Fusobacterium necrophorum following trauma or viral infection (IBR). Can also occur as part of oral necrobacillosis in calves and swine.
Plaques of ulceration covered by fibrinonecrotic exudate.
Lesions are associated with ulcerative damage to the larynx. Caseous fibrino-necrotic type of exudate. Fusobac. necro is present in the environment so animals that present with Calf diptheria hav ehad IBR whch may hav resulted in mild ukcerative erosive elsions in URT including th karynxl. This bacteria will proliferate and produce this type of laryngitis with a lot of caseous material.
name of disease: necrobacillosis
primarily in calfs and sometimes in pigs
Larynx
Laryngeal hemiplegia
(paralysis) – “roaring”
horses. Atrophy of the left dorsal cricoarytenoid muscle.
Usually the result of an idiopathic neuropathy affecting the left recurrent laryngeal nerve which innerrvates this muscle. Right side for soem reason is not effeted; unsure as to why. The left one is very long and can even enter the thoracic cavity and come back which is why it is more susceptible to trauma.
Dorsal view of larynx. The larynx is not opened. Arrows in crychoid. Symmetric atrophy of the muscle that is the crychoid erythinod muscle tht is one of the abductors of the larynx (open). Animals that are exercising need these muscles to contract so thst they can inspirate alarge amount of air.
Asymmetric atrophy.
Roaring affects athetic performance of horse
Tracheal collapse: Mainly in toy and miniature dog
breeds; occasionally seen in miniature horses, cattle
and goats.
Results in some dgree of exercise intolerance. Animals tend t huff and puff after exercise. Chronic coughing on presentation, dyp0snea, exercise intolerance, airway obstruction in more severe cases;.
Looking at dorsal surface of trachea Trachea looks very flat b/c normally the cartilage is ring like and on top there is the dorsal trachela membrane which is made of soft tissue. Widening of the dorsal tracheal ligament –> trachea is stenotic and the ligament is flat –> issues.
Tracheal stent placement in severe cases of tracheal collapse. Animals are more susceptibel to develop resp. infections.
Dorso-ventral flattening of the trachea and
concomitant widening of the dorsal tracheal
membrane, pony.
May result in coughing and exercise
intolerance.
In horses is referred to as “scabbard
trachea”.
IBR Cattle
UCVM-08, OI, feedlot heifer.
Etiology: BoHV-1
Ulcerative and necrotizing
laryngo-tracheitis
Seen in beef cattle primarily b/c you have a concentration of relatively long animals, steers and heifers. Ulcerative, hemorrhagic, necrotizing rhinitis with the presence of diptheric membranes. Necrotic exudate present.
Same lesions can extend into the larynx and trachea. fibrinonecrotic exudate in the larynx and along the trachea, mucosa, submucosa, edematous congesive hemorrhagic.
CAn peel off, producing a diptheric membrane in some areas. Can see ulceration in these areas
Virus can also inect bronchial eoith and priduce a bronchal insterstial pneumonia
Debris goies down into lungs whch is why they develop pneumonia
This neonatal calf is suffering from a systemic herpesvirus infection called _______. Lesions are characterized as _______-_______ and can be found int he __________. This condition will also produce necrotizing _______.
Systemic herpesvirus infection in neonatal cavles
IBR can affect neontes –> systrmic infection
Lesions seen are ulcerative, necro lesions in rumen (ulcer necro rumenitis) and will also produce a necrotizing hepatitis.
Provide a MDx based on the image below.
Multifocal necrotizing hepatitis
Miliary necrotizing hepatitis b/c there are thousands of small foci of necrosis usually 1-2 mm in size.
- The horse pictured below is suffering from?
- This syndrome is similar to?
- What was this condition previously known as?
- What is this condition caused by?
- What are some of the major clinical signs? Chronic clincial signs?
- Horses living in this type of environment are at a greater risk of suffering from this condition.
- Horses and ponies– chronic bronchiolitis-emphysema complex, “heaves”, “broken wind”, Recurrent Airway Obstruction (RAO).
- Asthma-like syndrome
- Used to be known as Chronic Obstructive Pulmonary Disease (COPD). Similar clinically, but pathogenesis is different.
- Has to do with allergic reaction to something in envir; poor quality, dusty hay, something ? in the barn.
- Head and neck are extended, nasal flaring with mucoid nasal discharge, dypsnea. In chronic cases, you will see hypertrophy of external abdominal oblique muscles as a result of expiratory efforts.
- Higher risk if animal lives in stable (closed).
The main pathology of Recurrent Airway Obstruction (RAO)/Heaves is _______ accumulation (_______ cell _________ within ________).
Clinical signs are caused by __________ to airflow in the lung because of diffuse _________. They are usually worst in _______ when horses stay housed _______ and the ventilation of barns is _________.
mucous, goblet, metaplasia, bronchioles
Clinical signs are caused by resistance to airflow in the lung because of diffuse bronchoconstriction. They are usually worst in winter when horses stay housed indoors and the ventilation of barns is sub-optimal.
This is a histological image of a sample taken from a horse suffering from RAO.
1. What type of stain is being used here?
2. Exposure to ____________ are implicated in the pathogenesis of the disease.
- HE stained histo slide
- Exposure to aeroallergens are implicated in the pathogenesis of the disease.
- What diseases are similar to RAO?
- Describe the pathogenesis of this disease.
- Other similar disease in veterinary medicine : Feline asthma, a.k.a. feline allergic bronchitis. “Hyperactive airway disease”
- Constriction of airways, Hypertrophy of smooth muscle b/c always having these attacks, will see presence of abundant goblet cells, Will also see eosinophils (parasites, allergies).
Epistaxis and pulmonary hemorrhage are relatively common in cattle suffering from?
Epistaxis and pulmonary hemorrhage are relatively common in cattle which develop pulmonary abscesses as a complication of vena cava
thrombosis.
Pathogenesis of ^
high carb diet –> bouts of chemical rumenitis –> erosion of mucosa of rumen –> bacteria enter into systemic circulation –> portal vein –> abscess in cranial portion of liver, close to vena cava –> rupture of abscess into vena cava –> septic shock –> acute death OR slow leakage of septic contents of abscess —> formation of septic emboli due to septic thrombi –> enters caudal vena cava –> attacks to right articular valve –> valvular endocarditis develops on right side.
Septic emboli can enter PA –> lungs –> pulmonary hemorrhage.
What can be seen here?
Pulmonary edema, pig
Lungs appear moist/wet/shiny.
Look swollen as well b/c contain fluid.
Heavier than normal
What can be seen here/
Pulmonary edema, frothy fluid on pleural surface.
Lungs in horses do not much have CT between interstitium, but that differs in other species.
Chronic pulmonary edema
Chronic cardiogenic pulmonary edema (increased cellularity –> due to increased presence of heart failure cells).
HE-stain, dark brown pigment within the cytoplasm of alveolar macrophages
(“heart failure cells”).
When we have cardiogenic PE, that is allow protein edema so it does not pick up a lot of eosin stain, so we may not be able to see it microscopically.
Iron (Perl’s) stain – Hemosiderin- laden macrophages (“heart failure cells” → siderophages) within alveoli
Animals do not typically survive long when have CHF so we rarely get to see this
What type of pigmentary disturbance is pictured below?
Pigmentary disturbances: Pulmonary Anthracosis
Carbon particles within the pulmonary parenchyma.
Pinpoint, blackish foci on surface of lungs.
This is a key characteristic
Change is not associated with any clinical problem. Is a subclinical condition.
MCQ with brownish pigment –> carbon particles.
Mineral dust within lungs is referred to as Pneumoconiosis.
Pulmonary atelectasis – bovine fetus. In addition
to fetuses also present in stillborn animals. If you see this, then the animal was born dead b/c animal could not breathe with lungs like this.
If lungs look like this diffusely, if take piece of lung and put in water, the lung will sink b/c it is not aerated. Also seen in cases of pneumonia due to exudate in parenchyma.
Aspiration of amniotic fluid does not produce major problems b/c contains ? epithelium.
If fetus aspirate meconium, the first feces eliminated in the first 24 hours after birth. If supper hypoxia in utero, response is dilation of anal sphincter –> defecate in amniotic fluid –> susceptible to aspiration –> respiratory problems in neonatal life.
Meconium staining in a kitten fetus
Indicates that animals died in utero
Patchy pulmonary atelectasis (darker, depressed) due to aspiration of meconium and amniotic fluid-calf, 1 day old.
Meconium –> irritatn –> inflammtory response –> pneumonia –> risk of death
Cow, pulmonary edema emphysema,fog fever.
Bullous emphysema: Large focal air-filled spaces (bullae)
→rupture –> loss of negative pressure —> agalectisus, may lead to fatal pneumothorax.
Alveolar emphysema = air within parenchyma
Bovine, interstitial emphysema
