SA Respiratory

What can be seen on expiratory thoracic radiographs

Heart appears larger and may overlap with diaphragm
Enhanced bronchial pattern in caudo-dorsal lung field

How is exposure checked on thoracic radiographs

Should have good differentiation between dorsal spinous processes and epaxial muscles

Radiological appearance of generalised cardiomegaly in dogs

\>2.5 (deep chested)/\>3.5 (barrel chested) intercostal spaces wide and 70% height of thorax
\>65% of space on DV view
Elevated trachea (runs parallel to spine)

Radiological appearance of generalised cardiomegaly in cats

\>2 intercostal spaces wide
Valentine's heart shape on DV

Radiological appearance of left atrial enlargement

Very upright caudo-dorsal border
LA may appear triangular
May see splitting of caudal mainstem bronchi = appears bow-shaped = cowboy sign

Radiological appearance of aortic root dilation

Bulge at 11-1 o'clock position

Radiological appearance of pulmonary artery dilation

bulge at 1-2 o'clock

Radiological appearance of PDA

classical triple-knuckle sign

Radiological appearance of pericardial effusion

Large and round heart
Clear margins to cardiac shadow (as fluid smooths out movement due to heart beat)

Ultrasound appearance of pericardial effusion

Anechoic area surrounding heart
Rounded outline

Ultrasound appearance of pleural effusion

triangular shaped anechoic areas

Where are cardiac masses usually located

RA or heart base

How is LA enlargement measured

RPS short axis through heart base - image frozen when 'mercedez-benz' sign visible and ratio of aorta to LA measured

How is the ejection fraction (Simpsons rule) measured on US

RPS long axis through LA and LV
Reduced contractility when difference between diastole and systole is

How is LV dilation measured on US

RPS short axis through MV (fishmouth)
Distance between MV leaflet and interventricular septum should be

Colourflow doppler colours

BART
Blue = away
Red = towards

5 radiographic lung field patterns

Alveolar
Bronchial
Nodular
Interstitial
Vascular

What is the size cut off between a nodule and a mass

3cm

Alveolar pattern on lung field radiograph

Replacement of air with fluid/cells
Begins as fluffy amorphous margins
Bronchi may remain air-filled and will therefore be visible = air bronchograms

Causes of alveolar pattern on lung field radiographs

R CHF (associated with cardiomegaly)
GA and hypostasis (seen in lower lung)
Aspiration pneumonia (cranio-ventral region)
Bronchopneumonia (caudo-dorsal region)
Haemorrhage (widespread changes)

Bronchial pattern on lung field radiographs

Thickened bronchial walls appear as 'donuts'

Causes of bronchial pattern on lung field radiographs

Normal age-related change
Chronic bronchitis (associated with cough, will see hazy surrounding areas if active bronchitis)
Bronchopneumonia/Eosinophilic pneumonia (will also see alveolar pattern)

Why should 3 radiographic views be taken to investigate lung nodules

Nodules are only visible when surrounded by air so cannot be seen in hypostatic lung

Miliary nodules in the lungs

Multiple small lesions which are stacked to become visible
Blurry edges due to overlap
Differentiated from alveolar pattern due to lack of air bronchograms

Vascular pattern on lung field radiograph

Increased diameter of pulmonary arteries and veins

Causes of vascular pattern on lung field radiograph

Congenital heart defects
Heartworm
Severe L CHF

Interstitial pattern on lung field radiographs

Mild to moderate hazy appearance which may be homogenous or composed for finely structured linear, reticular, honeycomb or nodular opacities
No silhouetting of bronchi

Sonographic appearance of the normal lung

Can only visualise the hyperechoic pleural surface
Beyond this line is the acoustic shadow containing A lines (reverberation artefact)

Sonographic appearance of the diseased lung

Reverberation lines become more focal and hazier = called B lines/lung rockets

Sonographic appearance of pneumothorax

No lung movement

Sonographic appearance of collapsed lung

Echogenic triangular structures

When megaoesophagus is found why is it important to check the lungs

for aspiration pneumonia

Causes of persistent coughing

Respiratory
Bacterial/viral infection
Inflammatory/allergic/chronic airway disease
Neoplasia
Parasitic
Protozoa/fungi
Trauma/structural abnormalities
Cardiovascular
Cardiomegaly
Pulmonary oedema

Findings on auscultation for a cough due to cardiac causes

Tachycardia
Arrhythmias
Murmurs
Gallop sounds
Pulmonary crackles

Findings on auscultation for a cough due to respiratory causes

Sinus arrhythmia
Bradycardia
Crackles, wheezes
Stertor/stridor

How does right sided cardiomegaly appear on a radiograph

Inverted D shape on DV

Differentials for coughing in cats

Cat 'flu' (URT infection)
Pneumonia
Chronic airway disease (CAD)
Feline asthma
Neoplasia
Parasites
Fungi
Protozoa

Common causes of cat flu

Feline rhinotrachietis virus
Feline calcivirus
Feline coronavirus
Bordatella bronchiseptica
Mycoplasma sp.
Chlamydophila felis

Treatment for cat flu

Supportive
Appetite stimulant
Mucolytics/decongestants

Treatement for parasitic infection of the respiratory tract in cats

fenbendazole

Treatment for toxoplasma infection in cats

Clindamycin

Differentials for coughing in dogs

Infectious laryngotracheitis/Kennel cough
Chronic bronchitis
Allergic pulmonary disease/Eosinophilic bronchopneumopathy
Parasites
Neoplasia
Tracheal collapse
Foreign bodies

Causes of kennel cough

Brodetella bronchisepta
Parainfluenza III
Canine distemper virus
Canine adenovirus II
Canine herpesvirus
Mycoplasma sp.

Signs of kennel cough

Harsh, non-productive cough
+/- systemic signs

Treatment of kennel cough

Isolate animal
Reduce exercise

Treatment of chronic bronchitis in dogs

Avoid obesity
Use a harness rather than a collar
Corticosteroids
Bronchodilators
Mucolytics
Exercise control
Physiotherapy
Anti-tussives

Treatment of allergic pulmonary disease/eosinophilic bronchopneumopathy in dogs

Acute: O2 therapy and corticosteroids
Chronic: worming, corticosteroids, check environment for allergens

Common parasites causing coughing in dogs

Olserus osleri
Crenosoma vulpis (IH= molluscs)
Angiostrongylus vasorum (IH= molluscs)
Capillarea aerophilia
Dirofilaria immitis (IH= mosquitos)

Breed associations of tracheal collapse

Toy breeds

Signs of tracheal collapse in dogs

Honking cough
Dyspnoea

Ddx for inspiratory dyspnoea

Nasopharyngeal mass/stenosis
Laryngeal paralysis
Neoplasia
Tracheal mass/stenosis

Ddx for expiratory dyspnoea

Dynamic airway collapse
Feline asthma
Pulmonary parenchymal disease (e.g. pnemonia)

Ddx for dyspnoea affecting both inspiration and expiration

Pleural effusion
Pneumothorax
Pulmonary thromboembolism

What should be done immediately for a patient with marked dyspnoea

O2 supplementation

History questions for dyspnoea

Acute vs chronic
Concurrent signs (e.g. coughing)
Character (inspiratory vs expiratory)
Duration/frequency/timing
Relationship to activities
Vaccination/travel/worming
Respiratory noises
Exercise tolerance
Appetite
Previous treatment? and response

Which radiographic view should be avoided in dyspnoeic patients

DV

Orthopnoea

Inability to breath unless upright/sternal recumbency

Signs of a cardiac cause of dyspnoea

Tachycardia +/- arrhythmias
Murmurs +/- gallop sounds
No respiratory noise
Cyanosis may or maynot improve with O2 (depending on cause)

Potential consequences of mediastinal disease

Venous obstruction = oedema
Dyspnoea
Dysphagia = aspiration pneumonia
Horner's syndrome
Hypertrophic osteopathy (Marie's disease)

Idiopathic pulmonary fibrosis: breed association

West Highland Terriers

Idiopathic pulmonary fibrosis: signs

Tachypnoea
Dyspnoea
Exercise intolerance

Idiopathic pulmonary fibrosis: treatment

Glucocorticoids
Bronchodilators
Antibiotics for secondary infections
Pimobendan/Sdenafil (decrease pulmonary hypertension)

Idiopathic pulmonary fibrosis: prognosis

Guarded

Paraquat (herbicide) poisoning

Pneumotoxic - causes alveolitis and haemorrhage which progresses to fibrosis
Initially very few radiographic changes
Hopeless prognosis

2 common bacteria causing pneumonia in small animals

Bordetella sp.
Pasteurella sp.

Bacterial pneunmonia in small animals: treatment

Long course of antibiotics (i/v then oral)
O2 supplementation
Supportive care

3 viral causes of pneumonia in small animals

Canine distemper
Canine influenza
Feline calcivirus

Ddx for pulmonary oedema

CHF
Toxins
Anaphylaxis
Near drowning
Seizures
Electric shock
Overperfusion
Negative pleural pressure

Pulmonary oedema: treatment

Diuretics
O2 supplementation

Ddx for pulmonary haemorrhage

Trauma
Coagulopathies
Pulmonary thromboembolism
Angiostrongylus vasorum

Ddx for pulmonary thromboembolism

Angiostrongylus vasorum
Hyperadrenocorticism
IMHA
Nephrotic syndrome
Bacterial endocarditis
Corticosteroid therapy
Iatrogenic

Pulmonary thromboembolism: signs

Dyspnoea
Hypoxia
Sudden death
Right-sided cardiomegaly

Pulmonary thromboembolism: treatment

Heparin
Aspirin or Clopidogrel
Sidenafil
Treat underlying cause

Pulmonary thromboembolism: diagnosis

Contrast angiography and CT
Haematololgy and coagulation times

Pulmonary thromboembolism: prognosis

Poor

Feline asthma: acute management

O2 supplementation
Rest
Corticosteroids

Feline asthma: long term management

Control environment and parasites
Bronchodilators
Antibiotics if required
Corticosteroids

Ddx for acute dyspnoea in cats

Feline asthma
CHF
Lung contusion
Upper airway obstruction
Pneumonia
Hydro/pneumothorax
Diaphragmatic hernia

Signs of a respiratory cause of dyspnoea

Normal HR and heart sounds
Cyanosis improves on O2 (some cardiac causes may improve on O2, e.g. pulmonary oedema)
May have respiratory noises

Pneumothorax: treatment

Mild = rest and monitor
Moderate = thoracocentesis or thoracostomy tube
Severe (\>72h) = surgery (lobectomy)

Ddx for mediastinal disease

Masses
Megaoesophagus
Pneumomediastinum
Mediastinitis
Mediastinal haemorrhage

What causes stertor in small animals

Excessive soft tissue in the URT

what does BOAS stand for

Brachycephalic obstructive airway syndrome

Primary disorders of BOAS

Elongated soft palate
Stenotic nares
Excessive pharyngeal mucosa
= Narrowed nasal passages and decreased URT airflow

Why is BOAS progressive

Stertor causes inflammation and thickening of the soft tissue of the URT = narrowed URT
Increased respiratory effort causes increased negative pressure = mobile soft tissues collapse into the airway

Secondary disorders of BOAS

Soft palate thickening
Laryngeal saccule eversion
Laryngeal collapse
Tonsillar prolapse
Inflammation and swelling
Regurgitation

Simple surgeries for BOAS

Soft palate reduction
Opening of stenotic nares
Removal of laryngeal saccule eversion
Removal of prolapsed tonsils

BOAS signs

Brachycephalic breed
Snoring/stertor
Dyspnoea/cyanosis/collapse
Exercise intolerance (esp when hot)

BOAS: emergency management

Cage rest
Cooling
O2
COrticosteroids
Cautious sedation (butorphanol)

BOAS: long term management

Weight loss
Lifestyle changes (exercise, avoid heat and stress)
Harness not lead
Surgery

LAryngeal collapse: treatment

If due to BOAS - correct this
Surgically widen glottis
Permanent trachyotomy

Idiopathic acquired laryngeal paralysis: signalment

Older medium to large breed dogs

Congenital laryngeal paraslysis

Seen in first few years of life
Often: Bouvier des Flandres, Rottweilers, Dalmatians, White GSDs

Laryngeal paralysis: signs

Stridor (inspiratory noise at exercise)
Dysphonation (loss of bark/ hollow bark)
Exercise intolerance
May see acute exacerbation of signs

Laryngeal paralysis: diagnosis

Laryngoscopy (done during anaesthetic recovery)

Laryngeal paralysis: emergency management

Cooling
Sedation
O2
Tracheostomy
Antibiotics if due to aspiration pneumonia

Laryngeal paralysis: treatment

Crico-arytenoid lateralisation (tie-back)

Feline nasopharyngeal polyps

Feline nasopharyngeal polyps: signs

Stertor
Problems swallowing

Feline nasopharyngeal polyps: treatment

Traction (pull out) and steroids
Middle ear surgery in tympanic bulla