Respiratory tract diseases of SA 1 - The coughing dog and cat Flashcards
DDx - acute cough - 7
- Tracheobronchitis (KC) - Airway irritation - smoke, dust, chemicals, drugs - FB - Pulmonary haemorrhage - Acute pneumonia - Acute oedema - Airway trauma
DDx - chronic cough - 10
- Chronic bronchitis/bronchiectasis - Left sided heart disease (cardiomegaly –> compression) - Parasitic pneumonia - Tracheal collapse (mainstem bronchial collapse) - FB - Bronchopneumonia - Neoplasia - intrapulmonary or extralumenal - Eosinophilic diseases - dogs (eosinophilic bronchitis or pulmonary infiltrate with eosinophils), cats (FAD) - Pulmonary fibrosis - Ciliary dyskinesia
List parasites that can cause pneumonia in small animals - 3
Angiostrongylus vasorum (dogs) Filaroides (Oslerus) (dogs) Aelurostrongylus abstrusus (cats)
What should you assume if dogs have acute coughing that are otherwise well?
That the diagnosis is KC syndrome
What do you do in dogs with acute coughing that have signs not consistent with KC syndrome?
- Hx - PE - Thoracic radiographs (unlike cardiac patients where you always try to avoid anaesthesia)
Define ITB
Infectious TracheoBronchitis (i.e. Kennel cough, KC)
Define acute coughing
doesn’t persist for >2-3 weeks
Define chronic coughing
a cough that lasts > 3 weeks
Outline chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome
a syndrome characterised by chronic irritation to the bronchial mucosa –> increased mucous secretion, compromised respiratory defence mechanisms, coughing and bronchoconstriction. Increased mucous and bronchospasm –> airway narrowing –> compromised airflow. Also mucosal hyperplasia.
Does coughing itself cause damage?
Yes - repeated coughing cases repeated damage to the lower airways and perpetuates the inflammatory process.
Define PIE
Pulmonary infiltration with eosinophilia
Define FAAD
Feline allergic airway disease
Signalment chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome
any breed potentially. most commonly old small breed dogs (terriers), overweight too
Hx - chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome - 7
- good general condition - insidious onset - dry and hacking - unproductive - usually occurs in paroxysms - exacerbated by excitement/exercise - lead pulling often causes a bout of coughing (also cold temperature or humidity)
Clinical exam - chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome
- overweight (may) - harsh increased bronchial sounds - some wheezing - sinus arrhythmia (present or exaggerated) - cough often easily induced by tracheal palpation/pinch
Diagnosis - chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome - 5
BY EXCLUSION! - blood tests - usually normal - radiography - may show increased bronchial markings, false positives/negatives possible, may show bronchiectasis - Endoscopy - may confirm or rule out other causes - Tracheobronchial wash - mixed inflammatory cells and respiratory epithelial cells - Culture - often negative as secondary bacterial contaminants not always present
What are ‘doughnuts and tramlines’ on radiographs?
Indicates bronchiectasis: Tramlines - show the length of the bronchi Doughnuts - show the sectioned bronchi
Treatment - chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome
Education essential Unlikely to cure Patient management as important as drug therapy
Management recommendations - chronic bronchitis /bronchiectasis/chronic tracheobronchial syndrome - 5
- Clean atmosphere - Humidification of airway and coupage at home - Diet (especially if overweight) - Exercise regime - Avoid collars and choke chains - use ‘Halti type head collar instead
Drug therapy - chronic bronchitis/bronchiectasis/chronic tracheobronchial syndrome - 5
- BRONCHODILATORS (Theophylline, Terbutaline) - ANTIBACTERIALS (if bacterial infection is exacerbating signs) - EXPECTORANTS AND MUCOLYTICS - COUGH SUPPRESSANTS - ANTI-INFLAMMTORIES
How can you rule out a cardiac cause for a cough? 2
Presence of sinus arrhythmia and the absence of a murmur on auscultation.
What are the classes of bronchodilators?
XANTHINE agents - theophylline BETA-2 AGONISTS - terbutaline, adrenaline ANTI-MUSCARINICS - atropine
What are the classes of mucolytics?
Bromohexidine - useful in bronchial disease and bronchopneumonia to assist the expectoration of respiratory secretions
Define expectoration
the expel fluid from respiratory tract
What do anti-tussives do?
prevent/relieve a cough
Name 2 anti-tussives.
Butorphanol and codeine (both opiate derivatives)
When should you use anti-tussives? Contradindications?
To suppress a NON-productive cough. Helpful in cases of tracheal collapse and bronchial compression. Do not use to suppress a productive cough. Don’t use in patients showing radiographic alveolar pattern.
Why might anti-inflammatories be useful?
control cough due to inflammatory airway disease including chronic bronchitis + improved CS and QOL - too effective, animal/owner may become dependent on the drug, may lead to iatrogenic HAC, some disadvantages can be overcome with inhalation
Side effects - bronchodilators - 2
tachycardia and excitability
Expectorants - side effect
increase the productivity of cough
Side effect - corticosteroids
iatrogenic HAC
Side effects - cough suppressants - 2
trapping of airway secretions and sedation
Outline corticosteroid dose to suppress the inflammatory response in chronic bronchial disease?
they can be initiated at fairly high doses and then tapered to the lowest effective dose regimes.
Pathophysiology - tracheal collapse
abnormal flexibility of the tracheal rings and stretching of the dorsal ligament of the trachea resulting in a loss of the normal rigid cylindrical structure of the trachea –> dynamic variation in trachea diameter –> chronic coughing and sometimes dyspnoea. Cervical trachea collapses on inspiration. Thoracic trachea collapses on expiration.
Hx and signalment - tracheal collapse
small breed dogs - YT and miniature poodle Hx - chronic coughing, may be a characteristic ‘quacking’ type of cough due to collapse of the trachea during the coughing episodes.
PE - tracheal collapse
- usually fairly normal - may have audible clicking or slapping noise on inspiration or expiration - if trachea is very abnormal in outline, there may be a palpable abnormality of the trachea in the cervical region. The edges of the tracheal rings may be palpated.
Why might radiographs not show tracheal collapse?
collapse is dynamic.
Diagnosis - tracheal collapse
*** Fluoroscopy or endoscopy - show dynamic variation in trachea. Fluoroscopy doesn’t require anaesthesia but isn’t widely available.
What is fluoroscopy?
continuous xrays to monitor real time moving images (such as tracheal collapse).
How is the severity of tracheal collapse graded?
Grades 1-4 according to degree of change of tracheal diameter.
Treatment - tracheal collapse
- medical management to reduce the CS of coughing (like chronic bronchitis) - severe CS –> surgery to stabilise the trachea but this carries greater risk. External and internal prostheses (stenting) to stabilise the tracheal rings.
Prognosis - tracheal collapse
Mild - live happily with persistent cough. Signs may progress as the collapse can worsen with age. Severe (especially with signs of dyspnoea) - guarded prognosis although stenting can help.
List parasites causing canine lungworm - 5
*** Angiostrongylus vasorum*** - Filaroides (Oslerus) Osleri - Dirofilaria immitus (heartworm, non-UK) - Filaroides hirthii - Crenosoma vulpis
Effects of Angiostrongylus vasorum
- Affects pulmonary vasculature - may cause pulmonary hypertension and possibly pulmonary haemorrhage - Development of systemic coagulopathy and bleeding from any site. - Haemoptysis - Dyspnoea/wheezing
Where does Filaroides osleri affect? Signs?
WHERE: tracheal bifurcation EFFECTS: signs of airway irritation and coughing, haemoptysis
PE - canine lungworm
Nothing specific Maybe increased RE and noise
Diagnosis - canine lungworm
HAEMATOLOGY - maybe eosinophilia, blood test for angiostrongylus FAECES/TTW - may find larvae but false negatives common RADIOGRAPHY - may show characterisitc signs (A.vasorum –> alveolar/interstitial lung pattern, nodular interstitial pattern, pulmonary hypertension)) NODULES AT TRACHEAL BIFURCATION - Filaroides osleri BRONCHOSCOPY - characterisitc nodules with F> osleri. Larvae in tracheal washes. Evidence of eosinophilic inflammation.
What radiographic signs is characteristic of Filaroides osleri?
Nodules at the tracheal bifurcation
Treatment - canine lungworm
5-7 days of Fenbendazole (Panacur) at 50mg/kg Agents specifically licensed for tx of A.vasourm include moxidectin (Advocate) and milbemycin (Milbemax)
Prognosis - canine lungworm
may cases of parasitic pneumonia can be completely cured. Some cases of Filaroides have residual nodules at the tracheal bifurcation causing coughing. Overall it may take many weeks for the CS to completely subside because of the inflammatory granulomas within the pulmonary parenchyma. Also chronic pulmonary hypertension can lead to cardiac disease.
List causes of feline lungworm
Aelurostrongylus abstrusus Occasionally results in CS Alveolar/interstitial disease Prolonged fenbendazole course required.
What is the commonest cause of feline coughing?
Feline asthma = feline allergic airway disease = FAAD
Pathophysiology - FAAD
very similar to canine chronic bronchitis. Readtion to an antigenic stimulus –> airway inflammation –> excessive airway mucous, airway oedema and bronchoconstriction.
History - FAAD
intermittent episodes of dyspnoea and coughing which can be very acute in onset. There may be an identified stimulus.
PE - FAAD
normal between coughing bouts increased RE (maybe) lung hyperinflation expiratory wheezing CRISIS: severe dyspnoea, +/- cough
Diagnosis - FAAD - 3
BLOODS - circulating eosinophilia possible but often normal RADIOGRAPHS - widepread bronchial pattern, lung hyperinflation (very dark lung parenchyma and diaphragm flattening) TRACHEOBRONCHIAL WASH - usually an eosinophil predominance, care if there is a superimposed bacterial bronchitis.
DDx for FAAD
Aelurostrongylus abstrusus
Tx (crisis and maintenance) - FAAD
CRISIS - emergency therapy (O2, IV rapid-acting corticosteroids such as methylprednisolone succinate, IV bronchodilating agent such as atropine or adrenaline) MAINTENANCE - long term corticosteroids to control the inflammation (prednisolone, low dose, every other day). Control of the CS will be helped with bronchodilators (terbutaline, effective beta-2 agonist).Recentlyy cyproheptadine suggested to be useful as an additional therapy (anti-histamine and anti-serotonin)
Prognosis - FAAD
Provided the cat survives the acute episode of acute dyspnoea the long-term prognosis is fair although the cat will probably require chronic therapy.
What can nebulisers be used to administer? 2
Corticosteroids and bronchodilators.
Outline pulmonary neoplasia
PRIMARY SECONDARY - common metastatic site, tumour emboli deposit here, sarcomas commonly
Hx - primary lung neoplasia - 6
- May be no clinical signs • Some found incidentally on radiography • Often signs of cough due to airway involvement /erosion/compression • Haemoptysis • Weight loss • Rarely cause dyspnoea unless very extensive
PE - primary neoplasia
May be no abnormalities May be asymmetric findings: • Movement of apex beat • Unilateral decrease in resonance • Unilateral increase in respiratory noise
Dx - pulmonary neoplasia -4
RADIOGRAPHY - Solitary soft tissue density • DDx Neoplasia, granuloma, Abscess, Cyst, Haematoma CT – better resolution where available BRONCHOSCOPY - tracheal wash - Unlikely to be helpful unless affecting a major airway or very exfoliative BIOPSY - percutaneous “Tru-cut” or FNAB possible if mass superficial
Management - pulmonary neoplasia - 6
- Where mass small and shows no evidence of metastasis surgery is an option - Surgical lobectomy - High incidence of recurrence of CS - Some cases may be cured - Adjunctive chemotherapy described - MST: one year
Secondary neoplasia - DDx - 4
granulomatous disease, parasitic disease, deep fungal disease, TB
What do respiratory FBs do?
act as a persistent focus of inflammation/irritation, infection and airway obstruction. –> cough +/- focal pneumonia
Hx - FBs
typically acute onset with recognised event e.g. exercise • Often halitosis as FB degraded • Variable response to ABs/anti-inflammatories
PE findings - FB - 4
Often fairly normal • May be intermittently pyrexic • May have localised increase in respiratory noise • May have focal area of dullness on percussion
Diagnosis - FB - 2
Radiography - focal involvement of one lung lobe often right caudal lung lobe in dogs (due to lung anatomy and this having the largest bronchi/bronchiole) • Endoscopy allows visualisation and retrieval
Treatment - FBs
ENDOSCOPIC RETRIEVAL - may be fragmented and thus irretrievable SURGICAL REMOVAL - may be necessary, often need to carry out partial/complete lobectomy at the same time.
Define PIE What is it?
Pulmonary infiltrate with eosinophils. Syndrome recognised in dogs May be immune-mediated (allergic) cause History of chronic cough unresponsive to AB therapy May be seasonal May be association with other allergic diseases e.g. atopy
Dx - PIE - 5
- Bloods - Eosinophilia - Radiographic evidence of bronchial/alveolar pattern - Bronchoscopy - increased quantity of mucous in airways - Airway washes reveal population of predominantly eosinophils (there may be secondary bacterial infection and neutrophilic inflammation)
Tx - PIE
- Control secondary infection - Corticosteroids - immunosuppressive doses and gradually tapered to the lowest dose that controls the clinical signs. may wean off altogether
Prognosis - PIE
Excellent for control of CS but may require prolonged/lifelong therapy (coritcosteroids) with risk of iatrogenic HAC
When is KC commonest?
autumn time
What is the cause of pulmonary fibrosis?
idiopathic condition that seems to affect older WHWT most often. no effective Tx (some recommend corticosteroids and bronchodilators to slow progression but many dogs have progressive disease to which they succumb).
What is the toxin paraquat found in?
weedkiller
Diagnostic features - paraquat poisoning?
Severe progressive respiratory signs Dyspnoea most obvious Radiographs - interstitial pattern consistent with fibrosis
Prognosis - paraquat poisoning
supportive care can be provided but disease inevitably progressive. prognosis is poor.
