Respiratory Medicine: SA LRT Disease

Question 1

Main differentials for lower airway and lung parenchymal disease.

Answer 1

Cough, tachypnoea/dyspnoea.

Question 2

1. Canine chronic bronchitis.
2. Ages affected.
3. Often concurrent morbidities.

Answer 2

1. Chronic bronchial inflammation w/ over-secretion of mucus.
2. Middle-aged to older dogs.
3. Tracheal/bronchial collapse.
   Mitral valve disease.
   Pulmonary hypertension.

Question 3

1. Initial predisposing factors to canine chronic bronchitis.
2. What happens as a result of persistent coughing?
3. How can concurrent bacterial infections occur?
4. What does inflammation of the lower airways lead to?

Answer 3

1. KC, irritants/allergens, parasites.
2. Smaller airways become obstructed by mucus:
   - obstructive dyspnoea.
   - emphysema.
3. Alteration/disruption of the mucociliary escalator can cause this.
4. Narrowing of lower airways.
   Bronchomalacia = weakened cartilage.
   Bronchiectasis = end-stage bronchial change.

Question 4

Canine chronic bronchitis clinical signs and physical presentation.

Answer 4

Chronic cough >2mths - often productive (e.g. swallowing after coughing).
Gagging/retching.
Dyspnoea/tachypnoea.
Pyrexia if concurrent pneumonia.
On thoracic auscultation:
- wheezes.
- poss. crackles if concurrent pneumonia or emphysema.

Question 5

Diagnostic imaging for chronic canine bronchitis.

Answer 5

X rays.
CT scan.
Bronchial pattern - doughnuts and tramlines.
Poss. mild interstitial pattern - net curtains.
Mild broncho-interstitial pattern - can be normal in old dogs.

Question 6

Canine chronic bronchitis - bronchoscopy.

Answer 6

Look for mucosal erythema.
Look for excessive amounts of mucus.
Poss. take a bronchoscopy guided sample w/ bronchoalveolar lavage.

Question 7

BAL.

Answer 7

Bronchoalveolar lavage.
Guided w/ bronchoscope or blind.
Sample brings back mucus and neutrophils and possibly bacteria if canine chronic bronchitis.
If eosinophils seen, consider:
- Angiostrongylus vasorum.
- Eosinophilic bronchopneumopathy (not as common).

Question 8

Canine Chronic Bronchitis management.

Answer 8

Weight control - improve exercise tolerance.
Harness.
Avoiding airway irritants:
- Tobacco smoke.
- Dust.

Question 9

Tx. for Canine Chronic Bronchitis.

Answer 9

Glucocorticoids: Lowest poss. dose:
- inhaled fluticasone.
- oral prednisolone.
Bronchodilators:
- Theophylline.
- Methylxanthine.
May consider:
- ABX if suspicious of bacterial infection.
- Antitussives? – but cough is productive.
- Mucolytics? – may make mucus harder to remove from the lungs.

Question 10

Canine Chronic Bronchitis inhaled therapy.

Answer 10

Corticosteroids:
- Fluticasone.
Bronchodilator (acute signs):
- Salbutamol.
Not recommended for antimicrobials.
Often used once patient’s condition is stabilised.

Question 11

Canine Chronic Bronchitis - Antimicrobials.

Answer 11

Dept. on severity of clinical signs.
Ideally use C&S BAL result.
Need good airway penetration.
First line: Doxycycline.
- Broad spectrum.
– mycoplasma spp.
– Bordetella bronchiseptica.
- Empirical Tx 7-10d.
- Positive response – continue for 1 additional week past resolution of clinical signs.
- Can interpret response to Tx in light of any BAL culture post Tx and clinical response.

Question 12

Canine Chronic Bronchitis Px.

Answer 12

Chronic and progressive.
- may need to increase doses over time.
Can live for years if well managed.
Px worse if develop bronchiectasis or bacterial pneumonia.
Poss. concurrent mitral valve disease and/or pulmonary hypertension.

Question 13

Chronic bronchitis and heart disease.

Answer 13

Often co-exist.
- middle-aged small breed dogs w/ MVD and chronic bronchitis.
– murmur and cough.
- Stage B2 heart disease can cause cough due to cardiomegaly w/o CHF (enlarged atrium presses on airways).
- CHF usually causes tachypnoea/dyspnoea due to pulmonary oedema.
Advise owners to monitor RRR at home for MVD to keep an eye for changes to RR.
Radiography best for figuring out underlying cause.

Question 14

Tx of patients w/ bronchitis and heart disease.

Answer 14

Heart disease:
- stage B2 – Pimobendan.
- CHF – add diuretics: lowest effective dose (can dry out airways and exacerbate bronchitis).
Chronic bronchitis:
- Management!
- Bronchodilators.
- Minimise corticosteroids:
– fluid retention.
– can precipitate or worsen CHF.
– inhaled steroids better for patients that will tolerate.

Question 15

Dog w/ chronic cough stepwise approach.

Answer 15

Cardiac or respiratory?
Ideally chest radiographs (ideally inflated).
- +/- BAL.
- +/- faecal parasitology/Angiodetect.
Tx trials:
- Fenbendazole (parasites).
- Bronchodilators.
- +/- ABX.

Question 16

Feline lower airway disease.

Answer 16

Umbrella term encompassing “Feline asthma” and Feline bronchitis.
- Spectrum of FLAD.
- Asthma = bronchoconstriction in response to inhaled allergen or irritant.
- Chronic bronchitis more common in cats.
– see more permanent damage in airways that can arise secondary to a previous airway insult.
Acute bronchoconstriction.
Chronic bronchial inflammation (neutrophilic and eosinophilic).
Mucus hypersecretion.
Affecting young/middle-aged cats.
- Siamese cats over-represented.
Essential difference to dogs = BRONCHOCONSTRICTION.

Question 17

1. FLAD initial predisposing factors.
2. Hypersensitivity reaction associated w/ FLAD - effects.
3. Effects of bronchus obstruction.

Answer 17

1. Bacteria, virus, parasites, irritants/allergens.
2. Type I hypersensitivity (IgE mediated) reaction: histamine and serotonin production by mast cells.
   - smooth muscle contraction so acute bronchoconstriction.
   - oedema and eosinophilic inflammation of the lower airways.
   - mucus hypersecretion.
3. Large airways obstructed - atelectasis (collapse) of R middle lung lobe.
   Small airways obstructed - emphysema, bronchiectasis and possible pneumothorax (severe damage).

Question 18

FLAD clinical signs.

Answer 18

Spectrum:
- No signs, few signs, asthmatic crisis.
Cough (not indicative of heart disease as in dogs).
Asthmatic crisis:
- dyspnoea/tachypnoea – open-mouth breathing.
- cyanosis.
Thoracic auscultation:
- wheezes.
- +/ crackles if mucus/emphysema.
- +/- dull lung sounds if pneumothorax.

Question 19

FLAD investigations.

Answer 19

Thoracic radiographs:
- generalised bronchial/bronchointerstitial pattern – +/- patchy alveolar pattern.
- over-inflated lungs (air-trapping).
- poss. atelectasis of R middle lung lobe.
- poss. pneumothorax.
Radiographs can be normal - consider referral or more advanced imaging.
CT shows more subtle lesions.
- translucent chamber vs restraint / GA.
*generally thickened bronchial walls w/ parasitic infections - be aware!

Question 20

FLAD investigations cont… bronchoscopy.

Answer 20

Does carry some risks!
S/C terbutaline night and morning before procedure to reduce risk of v acute bronchoconstriction as can lead to death.
Have team members around who are aware of risks of bronchoscopy and how to manage them.
Can use to identify inflammation, mucus and airway narrowing.
Can use to conduct guide bronchoalveolar lavage (BAL).

Question 21

BAL.

Answer 21

Bronchoalveolar lavage.
Guided w/ bronchoscope or blind.
Cytology to look for mucus and inflammatory cells.
- eosinophil count:
– feline asthma >17% eosinophils.
– parasites.
- neutrophil count (chronic bronchitis more likely, feline asthma possible).
- mixed inflammation poss.
Bordetella bronchiseptica and Mycoplasma spp. PCR.
Aelurostrongylus abstrusus.
- cytology/PCR on BAL fluid.
- faecal Baermann exam.
- also high eosinophil count.
Bacterial C&S.

Question 22

FLAD emergency Tx.

Answer 22

Stress reduced.
O2.
Bronchodilators - Terbutaline 0.01mg/kg IM/SC every 4h.
Corticosteroids.
- Dexamethasone 0.15mg/kg IV/IM.
- Beware potential impact on subsequent cytology samples.
Sedation - Butorphanol.

Question 23

FLAD management.

Answer 23

Dust-free litter.
Cigarette smoke - no smoking inside the house.
Reduce use of aerosols.
Regular parasite control.
Monitor for secondary infections.

Question 24

FLAD Tx.

Answer 24

Glucocorticoids: lowest effective dose.
- inhaled fluticasone (topical).
- oral prednisolone.
- Depot injection of methylprednisolone acetate.
– cannot control dose.
– informed consent about risks.
Bronchodilators:
- oral theophylline long-term.
- inhaled salbutamol for acute bronchoconstriction.
- do not ctrl inflammation.
- should not be used as monotherapy (se steroids alongside).
Other treatments:
- Doxycycline if Mycoplasma infection.
- Fenbendazole if parasitic infection.
– give for 7d and repeat in 3w in clinical effect.

Question 25

FLAD inhaled therapy.

Answer 25

Corticosteroids - fluticasone.
Bronchodilator - salbutamol.
– acute bronchoconstriction.
Not recommended to give antimicrobials in this way.
Use once patient stabilise or in patient showing only mild signs.
Nebulisation not recommended.

Question 26

FLAD Px.

Answer 26

Varies.
Chronic has good Px if treated appropriately.
ACUTE CAN BE FATAL so prompt management is essential!

Question 27

1. Final destination of lungworms.
2. Most common spp. of lungworms.
   3.Heartworms that cause respiratory signs.
3. Why do some heartworms cause respiratory signs.

Answer 27

1. Lung.
2. Aelourostrongyls abstrusus (cat).
   Oslers osleri (dog).
   Crenosoma vulpis (dog).
3. Angiostrongylus vasorum - increasing UK prevalence.
   Dirofilaria immitis - in travelled dogs.
4. Move through the lungs as part of their life cycle.

Question 28

1. Angiostrongylus vasorum other name.
2. General life cycle of Angiostrongylus vasorum.

Answer 28

1. French heartworm.
2. By eating IH (mollusc) or paratenic host (frog).
   L3 larvae liberated in the intestines and travel to the pulmonary vasculature.
   Adult worms live in pulmonary arteries and R side of heart.
   Larvae migrate to the alveoli where they are coughed up (due to irritation) and swallowed. Then expressed in faeces.

Question 29

Angiostrongylus vasorum clinical signs.

Answer 29

Mild to fatal.
Respiratory:
- inflammatory response.
– chronic cough = most common sign.
– acute dyspnoea.
- severe pulmonary hypertension.
– Cor pulmonale (abnormal RV function and structure).
– syncope.
Bleeding diathesis:
- unknown mechanism.
- consumptive coagulopathy?
Neuro:
- CNS haemorrhage.
- retinal haemorrhages.

Question 30

Angiostrongylus vasorum investigations.

Answer 30

Lab findings may include:
- Anaemia.
- Eosinophilia.
- Thrombocytopenia.
- Abnormal coagulation times.
- Hypercalcaemia.

Question 31

Angiostrongylus vasorum Dx.

Answer 31

AngioDetect (patient-side blood test).
- antigen detection.
– positive: Dx.
– negative: A. vasorum v unlikely but another lungworm possible (C. vulpis?)
A. vasorum PCR (Dx and speciation).
Faecal smear.
Baermann faecal exam.
Empirical Tx.

Question 32

Angiostrongylus vasorum investigations.

Answer 32

Thoracic radiography/CT scan.
- combo of patchy bronchial, interstitial and alveolar patterns.
- peripheral distribution.
- no vascular changes (seen w/ Dirofilaria immitis).

Question 33

A. vasorum Tx.

Answer 33

Fenbendazole: 25-30mg/kg PO SID for 10-20d.
Moxidectin: 2 doses 30d apart.
Post treatment reaction: dyspnoea, ascites and sudden death due to sudden death of lots of worms - may be worth treating w/ lower dose over longer time.

Question 34

A. vasorum Px.

Answer 34

Depends on severity.

Question 35

Bacterial pneumonia poss spp. involved.

Answer 35

Pasteurella spp.
Klebsiella spp.
E.coli.
Pseudomonas spp.
Staphylococcus spp.
Streptococcus spp.
Bordetella bronchiseptica.
Mycoplasma spp.
Anaerobes.
*often a mixed infection.

Question 36

1. Route of bacterial infection causing pneumonia.
2. What can chronic bacterial pneumonia lead to?

Answer 36

1. Inhalation (e.g. aspiration), haematogenous spread.
2. Abscessation, pleural effusion, pneumothorax.

Question 37

Predisposing causes of bacterial pneumonia.

Answer 37

Chronic bronchitis.
Bronchiectasis.
Immunosuppression.
FB e.g. grass seeds, cereal awns.
Aspiration (R middle lung lobe):
- Brachycephaly.
- oesophageal disease.
- laryngeal disease.
- see bacterial pneumonia.
- or chemical pneumonitis – stomach contents.

Question 38

Bacterial pneumonia clinical signs.

Answer 38

Respiratory:
- cough (soft and productive (swallow)).
- mixed dyspnoea.
- tachypnoea.
- exercise intolerant.
- crackles and/ir wheezes on auscultation.
Systemic:
- pyrexia – normothermia does not exclude bacterial pneumonia.
- lethargy.
- inappetence.

Question 39

Bacterial pneumonia investigations.

Answer 39

Haematology - neutrophilia (left shift) / neutropenia.
- follow w/ in-house blood smear.
Hypoxia:
- SpO2 <94%.
- Arterial blood gas PaO2 <80mmHg.

Question 40

Bacterial pneumonia diagnostic imaging.

Answer 40

Thoracic radiographs/CT scan.
- usually alveolar pattern w/ ventral distribution (common).
- variable lung patterns.
- dorso-caudal distribution.
– haematogenous spread.
- Aspiration – R middle lung lobe –> obtain both lateral views.
- Early pneumonia – interstitial pattern.
- repeat x rays 48-72h later if unclear and high suspicion.

Question 41

1. Bacterial pneumonia bronchoscopy.
2. Bacterial pneumonia BAL.

Answer 41

1. Consider if the patient is stable enough.
   Useful for visualisation of the airways and potentially removing a FB if present.
2. Cytology - septic neutrophilic inflammation. – look for intracellular bacteria.
   Culture - aerobic and anaerobic.
   Bordetella bronchisptica and Mycoplasma spp. PCR.

Question 42

ABX for bacterial pneumonia.
- Empirical Tx.
- Aspiration pneumonia.
- Septic patients.
- Duration.

Answer 42

Ideally wait for culture result to reduce antimicrobial resistance.
PO doxycycline as penetrate airways.
If aspirational chemical pneumonitis, no ABX.
If aspirational bacterial pneumonia, treat w/ IV amoxycillin-clavulanic acid.
If patient septic, IV fluoroquinolones + ampicillin or clindamycin, treat gram positive bacteria and anaerobes, de-escalation ASAP.
Treat for 10-14d then reassess w/ clinical signs, haematology, chest x rays.

Question 43

Bacterial pneumonia Tx.

Answer 43

O2 supplementation if hypoxic.
IVFT - dehydration impairs mucociliary defences.
Nebulisation:
- increased mucus fluidity.
- no evidence for use of coupage.
Bronchodilators?
Treat any gastro-oesophageal reflux disease and oesophagitis.
- Omeprazole and metoclopramide or cisapride.
- pending further investigations.

Question 44

Bacterial pneumonia Px.

Answer 44

Depends on severity.
Refer when:
- suspicion of airway FB that cannot be managed in-house.
- Patient deteriorating on treatment.
- Pneumothorax and abscessation mat require lung lobectomy.
- Unable to diagnose or manage predisposing factors.

Question 45

1. Animals affected by eosinophilic bronchopneumopathy.
2. Cause of eosinophilic bronchopneumopathy.
3. What is it?
4. How can it be found/diagnosed?
5. Other differentials?

Answer 45

1. young dogs - huskies and malamutes.
2. immunological hypersensivity to an allergen (previous positive response to steroids).
3. Eosinophilic inflammation of lungs and bronchi.
4. By sampling or blood testing finding eosinophils or peripheral eosinophilia.
5. Parasites - rule these out if peripheral eosinophilia e.g. w/ faecal smear.

Question 46

1. Eosinophilic bronchopneumopathy on imaging.
2. Eosinophilic bronchopneumopathy on bronchoscopy
3. Eosinophilic bronchopneumopathy on BAL.

Answer 46

1. Mild, moderate to severe broncho-interstitial pattern.
2. Bronchial wall thickening.
   Mucus (green) +++.
   Bronchiectasis.
3. Eosinophilic inflammation.

Question 47

1. Eosinophilic bronchopneumopathy Tx.
2. Px.

Answer 47

1. Glucocorticoids.
2. Variable.

Question 48

1. Idiopathic pulmonary fibrosis signalment.
2. Clinical signs of idiopathic fibrosis.

Answer 48

1. Old dogs.
   Westies, bull terriers.
2. cough, exercise intolerance.
   +/- cyanosis.
   Inspiratory crackles.
   +/- right sided heart murmur.

Question 49

Dx idiopathic pulmonary fibrosis.

Answer 49

Imaging:
- interstitial pattern.
- NO alveolar pattern.
- Often “cor pulmonae”.
– enlarged R side heart due to pulmonary hypertension.
For definitive Dx:
- Lung biopsy.
- Rarely performed.

Question 50

1. Idiopathic pulmonary fibrosis Tx.
2. Px.

Answer 50

1. Sildenafil for pulmonary hypertension.
   - no evidence glucocorticoids beneficial.
2. Depends on severity.
   Progressive.

Question 51

1. Lung tumours.
2. Clinical signs.
3. Notable disease in cats.

Answer 51

1. Benign/malignant.
   Primary/metastatic.
2. Asymptomatic.
   Cough, haemoptysis, systemic signs.
3. Lung-digit syndrome.
   Primary pulmonary neoplasm w/ metastasis to the digits.
   Often present w/ foot issue/lameness.

Question 52

Dx lung tumours.

Answer 52

Radiographs or CT.
- CT more sensitive (for smaller nodules).
FNA/lung histopathology.
- risks of seeding tumours.
- experience necessary.

Question 53

1. Tx lung tumours.
2. Px.

Answer 53

1. Consider referral for lobectomy if well-differentiated tumour in a single lobe.
2. Px variable.
   If complete excision of tumour, mean 500d.

Question 54

1. Airway FB clinical signs and progression.
2. Confirm Dx of airway FB?
3. Airway FB Tx.

Answer 54

1. Acute onset cough and respiratory distress. Progression to secondary pneumonia +/-pulmonary abscessation.
2. Radiographs/bronchoscopy.
3. Bronchoscopic removal.
   Occasionally surgery.