1.1.4: Feline asthma and chronic bronchitis Flashcards

1
Q

Signalment for feline asthma

A

Young adult to middle aged cats; but can affect cats of any age
* Older cats -> more suspicious of other diseases e.g. neoplasia, cardiac disease, hyperthyroidism
* Younger cats -> more suspicious of infectious diseases

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2
Q

History and clinical signs associated with feline asthma

A
  • Lower airway disease in cats is variable in presentation
  • Usually low grade, chronic disease
  • Sometimes “acute on chronic” emergency presentation

Clinical signs
* Coughing (dry, harsh cough)
* Audible wheezing
* Exercise intolerance (less playful, reluctance to jump or play, being lazy etc.)
* If emergency presentation: acute development of clinical signs such as resp distress, mouth breathing, tachypnoea

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3
Q

Questions to ask when you suspect feline asthma

A
  • Any trigger factors (these are rare) e.g. environment, new cat litter, passive smoking, seasonal?
  • Is the cough productive?
  • Is anything brought up? (Often confused with hairballs)
  • Any significant weight loss, anorexia -> helps w/ other differentials e.g. heart failure, neoplasia
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4
Q

Discuss your approach to clinical exam of cat with breathing problems / history of a cough

A

These cats have minimal respiratory reserve and are easy to destabilise. If you stress them you can kill them.
* Initial exam: hands-off
* Remember transport to vets / being in consult room may be stressful
* Prioritise oxygenation - this is low risk and high benefit. Ensure cat does not overheat in an oxygen cage.
* Watch breathing
* Auscultate and listen for expiratory wheeze
* Auscultate and listen to heart rate, rhythm, check for murmurs etc. Remember that cats with heart disease may not have signs on auscultation!

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5
Q

You suspect a dyspnoiec cat to have heart disease such as HCM. On clinical exam, you find the cat is open-mouth breathing and stressed. On auscultation, there is no heart murmur. How does this alter your primary differential in this case?

A
  • Not all cats with heart disease have murmurs!
  • You cannot necessarily rule out HCM based on this finding alone - consider an echo / TFAST.
  • It would be sensible to reduce stress and provide oxygen to this cat before further diagnostics
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6
Q

Signs of upper airway disease

A

Laryngeal disease
* laboured inspiration (stridor, increased effort, slow inspiratory phase)
* ± change in purr or vocalisation (in dogs, bark becomes more high pitched)

  • Dysphagia ± salivation
  • Coughing/ gagging might be triggered by eating or drinking
  • Head shaking or behavioural signs may suggest nasal disease
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7
Q

Signs of lower airway disease

A

Often more subtle than upper airway disease.
* Laboured expiration: prolonged expiratory phase, additional expiratory push, audible expiratory wheeze
* Increased airway resistance due to bronchospasm, mucus, and bronchial wall thickening
* Occasionally may see paroxysmal cough (owners may think it’s a furball)

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8
Q

When does bronchial wall thickening occur and how long does it last?

A
  • Bronchial wall thickeneing occurs with repeated / prolonged lower airway disease
  • Over time, this becomes permanent
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9
Q

Characteristics of feline asthma

A
  • Reversible
  • Occurs secondary to inhaled allergen and airway hyperreactivity
  • There is bronchoconstriction
  • There is eosinophilic airway inflammation
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10
Q

Clinical signs of feline asthma

A
  • Episodic resp distress
  • Dyspnoea
  • Coughing
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11
Q

Clinical signs of chronic bronchitis

A
  • Coughing is a key feature
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12
Q

Characteristics of chronic bronchitis

A
  • Occurs in response to infectiion or inhaled irritants
  • There is airway damage and excess mucus
  • There is neutrophilic airway inflammation
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13
Q

True/false: feline asthma and chronic bronchitis are two distinctly different conditions.

A

False: it is basically a continuum between the two. They can be difficult to diagnose and overlap in presentation. They are also managed in similar ways.

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14
Q

What is air trapping and how could a cat with lower airway disease develop a pneumothorax?

A

Air trapping: trapping of air behind mucus and constricted airways, causing destruction of the alveoli.
* In rare cases, alveolar damage is so bad that leakage of air occurs (pneumothorax)

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15
Q

True/false: spontaneous rib fractures may be seen in cats with chronic lower airway disease.

A

True

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16
Q

Why do cats with lower airway disease present with dyspnoea?

A
  • Acute bronchoconstriction in response to a trigger factor
  • Inflammation of the bronchial mucosal lining with histamine and leukotriene release
  • Hyperreactivity of the bronchial smooth muscle in a Type ! hypersensitivity reaction. There is mucociliary imbalance.

Airway obstruction occurs due to bronchoconstriction, inflammation, and mucus plugs in the narrowed bronchioles.

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17
Q

True/false: lack of eosinophilia on haematology means feline asthma can be ruled out.

A

False
We may see an inflammatory haemogram inclduing eosinophilia in a cat with feline asthma. However, absence of eosinophilia does not mean we can rule out feline asthma.

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18
Q

Differentials for coughing in cats

A
  • URT disease
  • Inflammatory lower airway disease
  • Infectious cause: bacterial, viral, parasitic
  • Foreign body
  • Neoplasia
  • (Heart disease rarely causes coughing in cats; would expect them to present with dyspnoea).
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19
Q

Where is oedema formation typically in cats with heart failure and how does this impact their presenting signs?

A
  • Oedema is in pleura or abdomen
  • Even in there is alveolar oedema, cats tend not to cough
  • Tend to present with dyspnoea
20
Q

Differentials for hyperpnoea / tachypnoea in cats

A
  • Stress / pain / fear
  • Cardiac disease (causing pleural effusion / pulmonary oedema)
  • Resp disease (airways, lung parenchymal disease)
  • Pleural space disease
  • Mediastinal disease
  • Ruptured diaphragm
  • (Pericardial peritoneal diaphragmatic hernia - usually congenital and animals are fine)
  • Anaemia / hypovolaemia
  • CNS disease
  • Heatstroke
21
Q

When might you do a faecal analysis in a cat presenting with lower airway disease?

A
  • When suspicious of Aelurostrongylus abstrussus
22
Q

What might you need to take into account if performing bronchoscopy / BAL on a cat with asthma?

A
  • Take care - the airway is already hypersensitivie
  • You could cause severe bronchospasm
23
Q

When might you perform a trans-tracheal wash in a cat?

A

Never.
The risk of iatrogenic damage is too great.
Could instead perform an endotracheal wash.

24
Q

True/false: it is important to obtain a definitive diagnosis before treating the cat with dyspnoea.

A

False
You may choose to pursue a treatment trial (e.g. for feline asthma) if the cat is unstable and further investigations are risky, or if finances are limited.

25
Q

A cat presents with dyspnoea. After clinical exam you suspect airway disease. What do you do next?

A
  • Take care with handling - do not stress!
  • Pre-oxygenate the cat
  • Consider imaging e.g. TFAST to rule out cardiac disease, check for pleural effusion etc. Also consider thoracic rads (only GA your patient if they are stable!)
  • After initial imaging, you could then rule out other causes of coughing and dyspnoea e.g. via bronchoscopy, BAL / blind tracheal wahs
26
Q

A cat presents in dyspnoea and it is in crisis. You suspect airway disease. What are your next steps? Consider especially which drugs you will use.

A
  • Avoid stressing the cat
  • Oxygenate
  • Manage inflammation -> IV dexamethasone
  • Manage bronchospasm -> terbutaline (can give SC), consider also inhaled salbutamol
27
Q

You take thoracic radiographs in a cat with airway disease. What might you see?

A
  • Bronchial pattern ± interstitial pattern
  • May also see patchy alveolar pattern
  • Hyperinflation which is caused by air trapping. This leads to flattened diaphragm and large gap between diaphragm and heart.
  • May be normal (20% cats) - airway disease might not be severe enough to give you a clear bronchial
28
Q

What might you see on bronchoscopy of the cat with airway disease?

A
  • Hyperaemia
  • Oedema
  • Excess mucus
  • Decreased airway diameter
29
Q

Risks of bronchoscopy in the cat with airway disease

A

⚠️ Could aggravate irritable airways
⚠️ Could move mucus plugs
⚠️ Could cause bronchospasm (consider pre-treating with terbutaline and preoxygenate)

30
Q

You find eosinophilic inflammation on BAL. What are your differentials?

A
  • Feline inflammatory airway disease (asthma or bronchitis
  • Viral pneumonia
  • Parasitic cause
  • Hypereosinophilic syndrome (HES)
31
Q

True/false: heart failure is an absolute contraindication for BAL.

A

True
Do not perform BAL in a cat with heart failure.

32
Q

Long term management of cat with asthma

A
  • Reduce allergens - unlikely to be successful but some clients will try
  • Prednisolone PO for 2-3 weeks to allow cat time to accept inhaled treatment
  • Inhaled fluticasone (if improved)
  • If no response to prednisolone: repeat test for Mycoplasma, rule out lungworm. Consider ciclosporin.
33
Q

What disease can you cause by giving steroids to cat and which side effect should you look out for?

A
  • Steroids can lead to diabetes
  • If side effects include PUPD, steroid treatment must stop
34
Q

How does terbutaline work and what should you do before giving it?

A
  • Selective beta-2 receptor agonist
  • -> smooth muscle relaxant that causes bronchodilation
  • Rule out heart failure before giving it!
35
Q

How does salbutamol work and how do you give it?

A
  • Salbutamol = selective beta-2 receptor agonist. Give via inhaled route.
  • Can give every 30 mins for 2-4hrs
  • Stop if it stresses the patient
36
Q

What is feline lungworm and how do cats become infected?

A

Feline lungworm = Aelurostrongylus abstrusus
* Cats become infected by eating paratenic host (rodents, bird)
* Prepatent period = 1-2 months

37
Q

Clinical presentation of feline lungworm

A
  • Usually young cats affected
  • Most cats are asymptomatic
  • Some show mild coughing, may develop dyspnoea
38
Q

What might you see on radiographs of a cat with lungworm?

A
  • Similar appearance to inflammatory airway disease (bronchial ± interstitial pattern) + alvelar component if severe
39
Q

Diagnosis of feline lungworm

A
  • Identify L1 larvae (remember false -ves are possible)
  • Consider faecal flotation / Baermann’s technique
  • Airway wash analysis
  • Trial treatment: fenbendazole
40
Q

Treatment of feline lungworm

A

Fenbendazole PO (Panacur)

41
Q

How does Mycoplasma felis cause disease in cats?

A
  • Mycoplasma felis causes URT signs, but also lower airway disease
  • It may be a contributing factor in feline inflammatory airway disease
  • However, some cats carry Mycoplasma without any issues
42
Q

Clinical signs of Mycoplasma infection

A
  • Fever
  • Cough
  • Tachypnoea
  • Lethargy
43
Q

Diagnosis and treatment of Mycoplasma

A
  • Diagnosis: PCR on tracheal wash
  • Treatment: doxycycline 10mg/kg daily PO (warn owner re risk of oesophageal strictures so should always give with food or water)
44
Q

Clinical signs of mycobacterial pneumonia

A
  • Pneumonia is a late stage systemic spread of infection with M. bovis or M. microti
  • Early cutaneous signs: infection after bite from an infected vole or rodent. Non-healing sores or nodules ± large LNs
  • Early GI signs: infection after ingestion e.g. contaminated milk. Vomiting, diarrhoea, weight loss, poor appetite. Lesion = inflammatory granulomas.
45
Q

Mycobacterial pneumonia - diagnosis

A
  • Histopath, PCR
  • Seek advice - we need to consider zoonotic aspects
  • If it is M. bovis -> this is reportable!
46
Q

Treatment of mycobacterial pneumonia

A
  • Difficult
  • May take months of antibiotics (consider success rate, antimicrobial stewardship, and zoonotic risk - treatment may not be advised)
  • Usually need a combination e.g. macrolide + quinolone + rifampicin and possibly others