Feline inflammatory lower airway disease Flashcards
Describe Feline inflammatory lower airway disease.
▪ Feline asthma/bronchitis + many other names!
▪ Most common reason for cough in cats.
NB Cats with heart disease rarely cough!
If an old cat suddenly starts to cough, consider something other than asthma cause asthma’s onset is usually at a younger age.
▪ Inflammation causes reversible, smooth muscle constriction in the airways and Airway remodeling (from chronic inflammation) leading to a Smaller airway diameter in time.
Asthma/bronchitis - separate diseases or two aspects of the same disease?
There are Differences in pathogenesis.
▪ Asthma is thought to be an allergic disease causing airway constriction.
While bronchitis is inflammation of the bronchi.
▪ BALF eosinophils (asthma) vs. neutrophils (bronchitis) but often we don’t do BAL in cats (?)
xrays and clinical signs will not differentiate the two.
Does it really matter that we can’t differentiate them though? Right now, they’re treated the same way but in the future when we have novel treatments for asthma, it may be more important to accurately differentiate the two diseases.
Feline inflammatory lower airway disease - signalment
Commonly young and middle aged cats
▪ But All ages of cats can be affected
▪ Females, 2-8 years, Siamese
Feline inflammatory lower airway disease - clinical signs (5)
▪ Cough, increased respiratory effort, wheezing
▪ Chronic dry cough, paroxysmal cough
▪ Exacerbation of clinical signs, ”asthmatic attacks”
▪ Dyspnea, cyanosis
▪ History of exposure to allergens or irritants, stress, exercise
Feline inflammatory lower airway disease - examination findings
▪ Avoid excessive handling! (stress)
In Clinical examination:
▪ Cat can appear normal
▪ Auscultation may reveal expiratory wheezes or crackles (especially right middle lung lobe!)
▪ Tachypnea, expiratory dyspnea may be present
In Blood work:
▪ Peripheral eosinophilia in 20% of asthmatic cats
▪ Hyperglobulinemia possible
Feline inflammatory lower airway disease - thoracic radiography findings (5)
▪ Thickening of the airways
▪ Bronchointerstitial pattern
▪ Air trapping is pathognomonic (hyperlucency, flattening of the diaphragm) (lung looks too big and too black)
▪ Patchy or lobar alveolar infiltrates (most commonly right middle lung lobe)
▪ Radiographs can appear normal!
mild bronchial pattern
clear tram line visible in cranioventral lung field
left side of left image: right middle lung lobe forms some edges/triangular shapes due to collapse/atelectasis making it more dense then the other lobes
in right image the white line is the caudal border of the poorly aerated right middle lung lobe
right middle lung lobe changes, atelectasis causing increased density
cardiac sillhouette obscured
Feline inflammatory lower airway disease (both asthma and bronchitis) - bronchoscopy and BALF
▪ Bronchoscopic finding nonspecific, they do not distinguish asthma/bronchitis from other airway diseases.
Cats are prone to more complications from bronchoscopy so we don’t do it so often in them.
▪ Eosinophilia, neutrophilia or both in BALF in both diseases.
▪ No cut-off values what is normal
▪ Increased anesthetic risk!
Feline inflammatory lower airway disease - treatment during an asthmatic attack. (5)
Minimize stress! As few Diagnostic tests as possible.
Give Supplemental oxygen.
Sedation
▪ Butorphanol
Bronchodilator (more important in acute case)
▪ Terbutaline 0.01mg/kg iv, im, sc
▪ Inhaled salbutamol 100µg/puff 1 puff
Corticosteroids /more important in chronic case)
▪ Dexamethasone 0.2-0.4 mg/kg iv, im
▪ Hydrocortisone 5-10 mg/kg iv, im
2 bronchodilator options and routes in asthma attack
Bronchodilators
▪ Terbutaline 0.01mg/kg iv, im, sc
▪ Inhaled salbutamol 100µg/puff 1 puff (Ventoline evohaler)
2 Corticosteroid options and routes in asthma attack
Corticosteroids
▪ Dexamethasone 0.2-0.4 mg/kg iv, im
▪ Hydrocortisone 5-10 mg/kg iv, im
Feline inflammatory lower airway disease - Long-term management principles.
When to treat? When the cat is coughing more than once a week. Lifelong therapy!
Corticosteroids alleviate airway inflammation so bronchodilators aren’t enough. They’re good for getting the steroids to go deep enough.
▪ Prednisolone po 1-2 mg/kg po BID for 1-2 weeks, then gradual taper
▪ Fluticasone inhalation 50-250 µg/puff, 1 puff BID
▪ If severe, Start orally, then you may switch to inhalation. If mild, you can do inhalation immediately.
Corticosteroid dosage and treatment length depend on the severity of the disease and response to treatment!
NB Long-acting methylprednisolone injections offer no benefit in controlling the disease.
+ bronchodilator
+ eliminate asthma triggers
+ weight loss
Feline inflammatory lower airway disease - Long-term management principle: bronchodilators. (3)
Bronchodilators Alleviate clinical signs quickly but do not control inflammation which is why we combine with steroids.
Inhaled salbutamol (also called albuterol)
▪ One puff of 100µg when asthmatic attack, can be repeated in 30 min
▪ Pro-inflammatory, only use in asthmatic attacks
Combined salmeterol and fluticasone inhalation
▪ Longer acting bronchodilator
▪ One puff of 25 µg salmeterol / 125 µg fluticasone BID
Theophylline po (weak bronchodilator), terbutaline po (availability questionable?)
