Lower Airway Disease in Cats Flashcards
What is the signalment of lower respiratory disease in cats?
What is it liekly to be in young versus older cats?
Signalment
Lower airway disease tends to affect young adult to middle aged cats but can affect cats of any age
Older cats-increases suspicion for other disease such as
- hyperthyroidism
- neoplasia
- cardiac disease
Younger cats and kittens-increases suspicion for
- infectious disease
- viral
- parasitic
- Mycoplasma
- bacterial
- toxoplasma
**Bacterial pneumonia is relatively uncommon in cats compared with dogs**
What is the clinical history for lower respiratory track disease in cats?
Clinical History
Usually a low grade chronic disease
- coughing
What does a coughing cat look/sound like?
- audible wheezing
- “exercise intolerance”
Sometimes a very acute presentation
- brought in as an emergency
- respiratory distress
- mouth breathing
- tachypnoea
Episodic respiratory distress
- self limiting?
- respiratory effort?
What questions should we ask?
What questions should we ask?
- Are there any trigger factors?
- Change in environment?
- New cat litter?
- Passive smoking?
- Seasonal?
- Is the cough productive?
- Is anything “brought up”?
- Often confusion with hair balls
- Any significant weight loss, anorexia?
*
Is it an acute or chronic disease in cats?
Cats are excellent at masking their clinical signs
- quieter?
- staying in bed all day?
- less playful?
- grooming less?
- staying at floor level/reluctant to jump up on furniture?
- An emergency presentation doesn’t always mean an acute disease
Look at this schematic for lower airway disease in cats?
How to assess your patient/is it critical?
Assessing the cat: how critical is your patient?
Respiratory reserve often minimal
Sympathetic stimulation –> counterproductive (HR goes up and Oxygen requirement increases) caused by:
- transport
- waiting room
- is it “cat friendly”?
- physical exam
Initial assessment should be hands off
Triage emergency patients
- Are there trained staff empowered to make decisions?
What does the START anacronym stand for?
Simple Triage and Rapid Treatment
Treatment is often selected on a risk/benefit basis-if the risk is low and the benefit is high (eg supplementing oxygen) then the decision to treat is straightforward ” Prioritise oxygenation… START: simple triage and rapid treatment
How to assess respiratory pattern?
Respiratory pattern:
- watch and listen
- try to localise disease
Discuss the upper airway disease in terms of laryngeal disease?
Laryngeal disease
Laboured inspiration
stridor
↑ effort
slow inspiratory phase
+/-change in
- purr
- Vocalisation
Upper airway disease check for signs of?
Check the clinical history for signs of
- Dysphagia +/-salivation
- Coughing /gagging
- might be triggered by eating/drinking
- “Head shaking” behaviour
Signs of lower airway disease?
Lower airway disease: often more subtle
Laboured expiration
- prolonged expiratory phase
- additional expiratory push
- audible expiratory wheeze
↑ airway resistance due to
- bronchospasm
- mucous
- bronchial wall thickening
+/-occasional –> paroxysmal cough
- owners may think “fur ball”
Discuss physical exam with regards to lower respiratory track disease?
Physical Examination
Can be deceptively normal
- rule out other diseases?
Auscultation:
quiet room
listen for an expiratory wheeze
is the heart normal?
- no murmur
- no gallop rhythm
- no tachycardia
What is the most common cause of LRT disease?
Inflammatory
What is feline asthma?
- Reversible situation
- Immune mediated process
- Inhaled allergen
- Airway hyper reactivity
- Bronchoconstriction
- Eosinophillic airway inflammation?
Signs: episodic respiratory distress and dyspnoea
What is chronic bronchitis?
- Response to infection or inhaled irritants
- Airway damage
- Excess mucus
- Neutrophilic airway inflammation?
Signs: Chronic coughing is a key feature
Discuss feline asthma and chronic bronchitis?
Currently…. without a better understanding of the aetiology of these two conditions, there is a lot of overlap in terms of presentationand treatment is essentially the same
Why do things spiral out of control in LRT disease?
Pathogenesis: why do things spiral out of control?
Hyper-reactivity of the bronchial smooth muscle
- type I hypersensitivity reaction
- autonomic imbalance
- mucociliary imbalance (loss of function in the mucociliaryclearance systems)
Acute bronchoconstriction in response to a trigger factor
Inflammation of bronchial mucosal lining
- histamine and leukotriene release
Pathogenesis of LRT disease?
Airway obstruction occurs due to
- bronchoconstriction
- inflammation
- mucus in narrowed bronchioles
Air trapping because the lungs cant empty –> destruction of alveoli due to hyper inflated lung
End result is chronic damage
- irreversible situation due to remodelling
- may see spontaneous rib fractures
Extreme acute deterioration
- rare cases develop pneumothorax
- chronic airway disease in cat in crisis can mimic/appear like an RTC
What are some differential diagnoses for coughing in cats?
- Upper respiratory tract disease
- Inflammatory lower airway disease
- Most likely thing we will see in cats that are coughing
- Infectious – bacterial, viral, parasitic
- Foreign body
- Neoplasia
What are some differential diagnoses for hyperpnoea/tachypnoea (increased effort and rate)?
- Stress/pain/fear response - common response in cats
- mouth breathing
- CNS disease
- Anaemia/hypovolaemia
- Heatstroke
- Cardiac disease
- Respiratory disease
- airways
- lung parenchyma
- Pleural space disease
- In cats, they have a range of reasons for getting pleural effusion/fluid
- Mediastinal disease
- Cats like to get lymphoma
- Ruptured diaphragm
- Cars etc.
To investigate lower airway disease we need to formulate a safe diagnostic plan.
What are some things you would like to do?
- Haematology and biochemistry
- what should we look for?
- Hypereosinophilic syndrome?
- Anaemia of chronic disease?
- Biochemistry – not always that helpful in a coughing cat
- Diagnostic imaging
- radiography?
- ultrasound?
- advanced imaging?
- CT/MRI
- Bronchoscopy?
- +/- bronchoalveloar lavage – can be more targeted, but it’s a luxury we cannot always achieve in cats. We might be able to pop a catheter down the trachea and see if we can get anything back so we can send off for cytology and culture
- Can be useful, but not usually first line approach in coughing cats
- Endotracheal wash?
- Faecal analysis for parasites
When should we consider a treatment trial in cats with LRT disease?
- investigations at this stage are considered too risky?
- some owners are especially risk averse…
- owners cannot afford any diagnostics
Reaching a diagnosis is a luxury in some cases….
very often we just need to work with what we have.
History and physical exam are so important!
How should we go about planning for radiographs in cats with LRT disease?
What are we looking for?
Rule out other causes of coughing and dyspnoea
- Preoxygenate, never the wrong thing to do!
- GA –but only if stable
- Thoracic radiographs
- might be normal
- 20% of cats?
- bronchial pattern
- +/- interstitial
- hyperinflation
- air trapping
- collapse of R middle lung lobe? Worst lung lobe, aspirates
- patchy alveolar pattern?
- Aerophagia -> air in stomach
Why si GA often preferred to sedation when radiographing a cat with LRT disease?
Why is a GA preferred to sedation when we want to radiograph a cat with suspected airway disease? GA is better because you have got control of the airway, don’t want to have a sedated cat where respiratory effort is reduced and no control over the airways. With GA, can have full control and is often shorter acting
What do you see on this radiograph?
evidence of hyperinflation, quite a gap between diaphragm and caudal border of the heart. Normally would be closer together – this separation is often a hallmark of hyperinflation which is what we are looking for supportive evidence with inflammatory airway disease
When trying to rule out other causes of coughing and dyspnoea you could try bronchoscopy.
What are you lookig for?
What are some risks?
- Bronchoscopy
- hyperaemia
- oedema
- excess mucus
- ↓ airway diameter
- Think about the risks
- aggravating irritable airways
- moving plugs of mucus
- bronchospasm
When trying to rule out other causes of coughing and dyspnoea you could try a BAL.
What are you looking for?
What would you do with the sample?
- BAL/blind tracheal wash
- cytology
- interpretation difficult
- DDx for eosinophilic inflammation include
- viral pneumonia
- parasitic
- HES - hypereosinophilic syndrome
- bacterial culture
- Mycoplasma PCR
This is a BAL from a cat with CHF.
What can you see?
- Perl’s stain showing positive for iron (haemosiderin) in the macrophages
- Known as “heart failure cells” – don’t want to do a BAL on a cat with suspected heart failure!
- Feature of chronic congestion
- Reviewing the history for this 14 year old MN DSH cat who was referred for further investigations: he had lost some weight, was quiet and less keen to eat but not coughing. Physical examination revealed a heart rate of 250 (at rest) and tachypnoea (RR 38). Auscultation revealed a gallop rhythm and a systolic murmur (grade III/VI). We should not have airway disease at the top of the list of differentials for a cat like this
What is some treatment you would use in a crisis in a cat with LRT disease?
- Oxygenate
- Manage inflammation
- dexamethasone iv – potent anti-inflammatory drug
- Manage bronchospasm
- Terbutaline – bronchodilator for use in critical cases in cats
- selective β2 receptor agonist
- smooth muscle relaxant
- bronchodilation
- ideally rule out heart disease 1st
- inhaled salbutamol
- selective β2 receptor agonist
- can give every 30 mins for 2-4 hrs
- stop if stresses the patient
What is salbutamol?
- inhaled salbutamol
- selective β2 receptor agonist
- can give every 30 mins for 2-4 hrs
- stop if stresses the patient
To help manage bronchospasm
What is terbutaline?
- Terbutaline – bronchodilator for use in critical cases in cats
- selective β2 receptor agonist
- smooth muscle relaxant
- bronchodilation
- ideally rule out heart disease 1st
What are some longer term treatments for cats with LRT disease?
- reduce allergens?
- prednisolone po 2-3 weeks
- consider inhaled fluticasone if improved
- studies have confirmed route of delivery works
- some oral ingestion
- if no response to pred
- review case
- repeat test for Mycoplasma/or treat?
- have we ruled out lungworm?
- consider ciclosporin
If a cat is not responding to pred, what should you do?
- if no response to pred
- review case
- repeat test for Mycoplasma/or treat?
- have we ruled out lungworm?
- consider ciclosporin
What are some risks of cats on steroids?
Risks: steroids are diabetogenic in cats. If side effects include polydipsia and polyuria treatment must stop!
What is Aeleurostrongylus abstrusus?
Feline lungworm
Aeleurostrongylus abstrusus:
What is the PPP?
What is the clinical presentation?
- PPP 1-2 months
- Most infected cats are asymptomatic
- Clinical presentation
- usually young cats
- mild coughing but might à dyspnoea
- radiography: similar to inflammatory airway disease
What is the diagnosis and treatment of Aeleurostrongylus abstrusus in cats?
- Diagnosis:
- consider faecal flotation
- airway wash analysis
- Treatment trial: fenbendazole
What is Mycoplasma pneumonia associated with?
What are clinical signs?
- M felis associated with lower airway disease in cats
- might also cause URT signs
- Not all infections are significant
- might be a contributing factor in feline inflammatory airway disease
- Clinical signs: fever, cough, tachypnoea, lethargy
What is the diagnosis and treatment of Mycoplasma pneumonia?
- Diagnosis: PCR on tracheal wash
- Treatment: doxycycline – a good treatment for mycoplasma but also has some good immune modulation properties, so has some anti-inflammatory effeccrts
- Encourage swallowing after dosing orally, gently syringe some water after - can cause oesophageal strictures
Why should you encourage swallowing after administration of doxycycline?
Encourage swallowing after dosing orally, gently syringe some water after - can cause oesophageal strictures
What are some early cutaneous signs of Mycobacterial Pneumonia?
- Early cutaneous signs:
- after bite from an infected vole or rodent
- non-healing sores or nodules +/- large LNs
What are some early GI signs of Mycobacterial Pneumonia?
What is the diagnosis?
- Early GI signs:
- after ingestion eg contaminated milk
- vomiting, diarrhoea, weight loss, poor appetite
- lesion = inflammatory granulomas
- Diagnosis: histopath and PCR- seek advice because we need to consider zoonotic aspects
