Respiratory tract diseases of SA 2 - approach to dyspnoea and common conditions of the dog and cat Flashcards
What are the 4 main categories of dyspnoea causes?
Airway obstruction
Loss of thoracic capacity
Pulmonary parenchymal disease
Others - metabolic, physiological, vascular
What must happen to cause obstructive disease?
• Significant obstruction of the URT
OR
obstruction of a large number of the small airways of the LRT
What do URT obstructions sound like?
increased inspiratory noise (as URT tends to narrow on inspiration)
What do LRT obstructions sound like?
increased expiratory effect
List some causes of airway obstruction - 12
- Nasal obstruction
- rhinitis
- FB
- neoplasia
- polyp
- Trauma
- Laryngeal paralysis
- Tracheal collapse
- Brachycephalic obstructive airway disease (Soft palate, Stenotic nares, Laryngeal collapse)
- Filaroides
- Extralumenal mass lesions
- Asthma
Define BOAD
Brachycephalic obstructive airway disease
Broad causes - loss of thoracic cavity - 4
• Compromise due to Fluid/air in pleural space • Organs displaced from abdomen • Less commonly – Neoplasia – Marked cardiomegaly
DDx - loss of thoracic cavity - 7
– Pleural effusion – Pneumothorax – Neoplasia – Ruptured diaphragm – Cranial abdominal organ enlargement – Gross cardiomegaly – PPDH (pericardio-peritoneodiaphragmatic hernia)
Define PPDH
pericardio-peritoneodiaphragmatic hernia
List broad causes of pulmonary parenchymal disease - 3
- Diffusion abnormalities due to disease of the alveolar wall and interstitium
• Alveolar flooding with oedema, blood or exudate
• Abnormal pulmonary vascular supply
– Thromboembolism
– Ventilation-perfusion mismatch
Ddx - pulmonary parenchymal disease - 6
- Bronchopneumonia
- Pulmonary oedema - Cardiogenic or non-cardiogenic
- Neoplasia; primary or secondary
- Pulmonary haemorrhage
- Pulmonary fibrosis; idiopathic or toxic
- LRT parasites (Aelurostrongylus or Filaroides hirthii)
DDx - miscellaneous/ metabolic/ physiological causes of dyspnoea - 9
[MAY NOT BE ASSOCIATED WITH OBVIOUS ABNORMALITIES OF THE RESPIRATORY TRACT] - Hyperthermia • Obesity • Excitement/Exercise • Anaemia • Acidosis • CNS disease • Endocrine disease • Neuromuscular disease • Thoracic wall abnormalities
2 broad causes of pulmonary vascular disease as a cause of dyspnoea
- Pulmonary hypertension (causes increased RV afterload)
- pulmonary thromboembolic disease
What is the basic approach to a dyspnoiec patient?
- Same as other systems - history, PE, DDx, diagnostics
- BUT marked dyspnoeic cases may require emergency stabilisation first. Minimise stress (esp. cats). Oxygen supplementation will improve the dyspnoea.
What is the most effective technique to confirm pulmonary parenchymal or pleural disease?
Thoracic radiographs (n.b. URT obstruction, metabolic, physiological and vascular causes often have normal radiographs).
What should you do with your initial assessment of dyspnoeic patients?
Try to differentiate between types of dyspnoea
• OBSTRUCTIVE - URT obstruction and dyspnoea
associated with noise and increased inspiratory effort
– Laryngeal paralysis
– Tracheal collapse - honking sounds
• PLEURAL (i.e. loss of thoracic cavity)- decreased respiratory noise on auscultation, fluid line on percussion
• PULMONARY – may have increased respiratory noise on auscultation particularly wheezes and crackles
• METABOLIC/MISC.
How common is pulmonary parenchymal disease in dogs/cats?
Significant cause but probably overall less common than airway disease and pleural effusion.
List examples of pulmonary parenchymal disease in the dog/cat - 9
- Bronchopneumonia
- Pulmonary oedema - cardiogenic or non-cardiogenic
- Pulmonary haemorrhage
- Pulmonary neoplasia
- Pulmonary fibrosis
- Pulmonary infiltrate with eosinophils
- Parasitic pneumonia
- FAAD (feline asthma)
- Paraquat poisoning