Respiratory Disease Overview Flashcards
Lung Fields in the Bovine
- Caudal margin: From the 5th rib at the olecranon to the 11th intercostal space through the 9th rib and the point of the shoulder
- Cranial margin is a line drawn up from the 5th rib at the olecranon
What are 4 unique features of bovine lungs on a histologic level?
- Decreased Pores of Kohn
- Increased pulmonary intravascular macrophage
- Increased lobulation and interstitial tissue, which means they are more fibrous and therefore less compliant
- Reactive vessels and arteries (highly muscular, small)
What type of pneumonia do cows get?
- Bronchopneumonia instead of pleuropneumonia
How do decreased Pores of Kohn predispose cows to more respiratory issues?
- Pores of Kohn are openings between alveoli
- Bovine have decreased to nonexistent pores of Kohn
- Can’t equilibrate pressures across areas of lungs
- If you build pressure within an alveolus, it can either withstand the pressure or not
- If itcan’t withstand the pressure it will pop
- If one alveoli becomes too big alveoli, relative surface area to volume decreases so it’s more apt to pop again
- Extremely susceptible to emphysema because they can’t equilibrate and are more likely to rupture, which makes it even more likely to rupture again
Why are increased pulmonary intravascular macrophages not great?
- If they get reactive
Why are reactive bovine vessels bad?
- Highly muscular and small
- In hypoxia, there’s vasoconstriction, which will make this worse
Signs of respiratory disease
- Cough
- Nasal discharge
- Stridor
- Dyspnea
- Cyanosis
- Abducted elbow
- Exercise interolance
- Ozena
- Nasal erosions
- Distortion
Cough as a protective mechanism
- Involuntary
- May be suppressed if painful
Where are sensory receptors for cough?
- Pharynx
- Larynx
- Bronchioles
- Parenchyma
- Pleura
- You cannot localize a disease from a cough
Ozena
- Foul smell from the nose
Where does a productive cough localize? (GENERALLY)
- Lower respiratory tract
Where does a non-productive cough localize? (GENERALLY)
- Upper respiratory tract
Virus impact on epithelium
- Can denude epithelium and set up for secondary effects
- Animal may be coughing even after antibiotics are finished because it’s not fully healed
How long can it take for a denuded epithelium to heal?
- 6+ weeks for repair
Why don’t cows generally get nasal discharge?
- usually keep it clean
How can unilateral or bilateral nasal discharge help you?
- If it’s one sided, might be more localized (like sinusitis)
- If it’s one sided, might help you rule out lung disease more
Where is disease if you hear stridor on PE?
- Extra-thoracic
- 50% due to nares
Who can do mouth breathing?
- Cattle/sheep/goats
Who is an obligate nasal breather?
- Camelid
Stridor
Wheezing
If it’s expiratory dyspnea, where can you localize?***
- Typically within the thoracic cavity
If it’s inspiratory dyspnea, where can you localize?***
- Typically extra-thoracic
Normal lung sounds
- Bronchial, bronchovesicular, vesicular sounds
- Can increase with fever, exercise, etc.
- Can decrease with fat, cold, etc.
What are abnormal sounds called?
- Adventitial sounds
Examples of abnormal sounds?
- Crackles
- Wheezes
- Pleural rubs
- Absence of lung sounds
Epistaxis
- Blood at nares
Hemoptysis
- Coughing up blood
What can hemoptysis be pathognomonic for?
- Caudal vena caval thrombosis
Nasal causes of epistaxis or hemoptysis
- Foreign body, tumor, etc.
Pulmonary causes of epistaxis or hemoptysis
- Caudal vena cava thrombosis
- Lung abscess, etc.
Reminder of CVCT?
- Sequelae to liver abscesses secondary to rumen acidosis
- Shower lungs with bacteria and get abscesses
- If it ruptures into the caudal vena cava, they shower their lungs with pus, which would kill them
- If you see an animal like this, often needs to be euthanized or salvaged
Dyspnea
- Clinical sign meaning shortness of breath
- Labored breathing
- May open their mouth, elbows abducted, etc.
Respiratory conditions that can cause dyspnea
- Pneumonia, pleuritis, pulmonary edema, etc.
Non-respiratory conditions that can lead to dyspnea
- Cardiovascular
- Systemic disease
- Toxicity
Cardiovascular disease that can lead to dyspnea
- Anemia, heart failure, shock, dehydration
Systemic disease that can lead to dyspnea
- Pain, hyperthermia, acidosis
Toxicity
Organophosphates, carbamates, nitrate, cyanide, Taxus (yew)
Diagnostic procedures for respiratory disease
- History
- Clinical
- Environment
- Management
- Signs
What causes lung sounds?
- Turbulence of air
At the periphery of the lung fields in a healthy animal, what should you hear?
- SHouldn’t hear anything beyond the 7th branching airway
- Air filled lungs diminish the sound
What will you hear in a consolidated lung field?
- More sound
- Solid tissue propagates the sound better I guess
Where do you hear bronchial sounds?
- Listened to over the trachea
- Inspiratory and expiratory
- Pay attention to inspiratory and expiratory sounds
Where to hear bronchovesicular sounds
- Right over the hilus
- Typically hear inspiratory and expiratory
Where to hear vesicular sounds?
- At the periphery
- Pretty quiet
- Should hear inspiratory sounds but likely won’t hear expiratory sounds
- If you hear expiratory vesicular sounds, that’s suggestive of respiratory disease or consolidation
Rank the order of which sounds (bronchial, bronchovesicular, vesicular) have the loudest expiratory noise?
- Bronchial (insp and exp about equal length, but inspiration is louder)
- Bronchovesicular
- Vesicular (MOSTLY inspiratory)
Other ways to diagnose respiratory disease besides history and PE?
- Percussion
- Radiographs
- Ultrasound
- Endoscopy
Percussion
- Pleximeter and tap around
- People who are adept can detect changes up to 7 cm deep in a tissue
Radiographs for LA
- Possible, but it has to be small enough
- Less frequent
Ultrasound for LA respiratory disease
- Great for pleural disease and consolidation
- If you have healthy lung with air, it will reflect off
Endoscopy for LA respiratory disease
- Typically have to be really heavily sedated
- Will chew up endoscopes
- Maybe for laryngeal problems
Trans-tracheal wash (TTW) - where does the sample come from?
- Pooled secretions of the caudal lung fields (mixed with upper airway material)
- Does NOT directly sample parenchyma
Cytology on TTW
- Poorly correlated with culture and clinical signs
Culture for TTW
- Most useful part
- He still isn’t a huge fan, because you can isolate pathogenic bacteria from normal animals
Complications of TTW
- Cut tubing
- Emphysema
- Local infection
Bronchoalveolar lavage - where does the sample come from?
- Airways nearest parenchyma (lower airway to alveoli)
- Limited area sampled
Bronchoalveolar lavage advantages compared to TTW
- Easy to perform
- Good for cytology
Bronchoalveolar lavage sterility
- Non-sterile
Thoracocentesis site
- Percussion
- Ultrasound
- 6th or 7th intercostal space at the costochondral junction
- Penetrate near the front of the rib
In the bovine, are the two pleural compartments connected?
- No, they are separate
Normal thoracocentesis fluid in a bovine
- WBC <10,000/µL
- Protein <3.5 g/dL
Sinus trephination
- Not done as much
Lung biopsy
- Doable when appropriate
Arterial blood gas
- Hard to get in a ruminant
- Maybe an auricular artery or carpal in a calf
Nuclear imaging
- hard with withdrawal times
