Veterinary Cardiorespiratory Centre Martin Referral Services, Thera House, 43 Waverley Road, Kenilworth, Warwickshire CV8 1JL Tel: 01926 863445

INFORMATION SHEET

Idiopathic Pulmonary Fibrosis (IPF), synonym: Fibrosing Alveolitis

A common disease I see (amongst other colleagues) in WHWTs, Cairns and JRTs is idiopathic interstitial pulmonary fibrosis (probably a fibrosing alveolitis - cf. in man). Clinical Signs The typical features are: older and overweight dogs, tachypnoea/dyspnoea, sometimes a low grade productive cough (due to mucus accumulation in the airways), lethargy, marked exercise intolerance and on examination often pronounced pulmonary coarse crackles (esp. ventrally and usually on inspiration). Cyanosis can be seen after exercise or stress. The heart often seems muffled on auscultation. ECG There is often a marked arrhythmia, from respiratory sinus arrhythmia to episodic sinus arrest. However bradyarrhythmias (eg. sick sinus syndrome) are also not uncommon in this breed without IPF. Prolonged sinus arrest may result in syncope. If there is a bradydysrhythmia perform an atropine response test - inject 40g/kg s/c then recheck heart rate + ECG in 30 to 40 minutes. Radiography If taking radiographs under GA, the lungs are notably stiff to inflate. Chest radiographs reveal a marked cardiomegaly, which can appear generalised, but is usually right sided due to cor pulmonale. The lung fields show a mixed, predominantly interstitial and bronchial pattern, and it’s hard to obtain inspiratory views, even with lung inflation. Bronchoscopy It is important to rule out chronic bronchitis and to this end bronchoscopy should be considered. Doppler Echocardiography This is necessary to confirm if the cardiomegaly found is right sided due to cor pulmonale with evidence of right ventricular hypertrophy and Doppler studies indicative of pulmonary hypertension. Prognosis The prognosis is poor as this is a slowly progressive disease and responds poorly to treatment. Pulmonary thromboembolism and acute dyspnoea with death can occur when there is severe pulmonary hypertension. Treatment Currently the recommended treatment is steroids (preds at 1mg/kg bid for 2 or 3 weeks and then gradually reducing to the lowest effective alternate day dose) with Corvental (10mg/kg sid initially). If there was a poor response to this then I would often add a beta-agonist bronchodilator such as clenbuterol which is available as 25g/ml syrup (Ventipulmin, Boehringer Ingelheim). The dose rate is 1 to 5 g/kg bid/tid. Covering antibiotics are sometimes required. For some reason there can be a mild response to gentle diuresis - although diuresis is generally not advocated for most airway diseases, as maintaining airway humidification is important. Weight loss is very important in this condition and this alone can produce a great improvement in the dyspnoea. If there is pulmonary hypertension, then ACE inhibitors might have a mild effect. For a bradydysrhythmia - responsive to atropine - try oral treatment with probantheline 15mg tablets at 0.25 to 0.5mg/kg tid (this is cheaper than oral atropine). Research We are currently engaged with medical colleagues who are also researching this condition in people and we require heart and lungs at post mortem if at all possible. Only through continuing research can we further our understanding of this disease and ultimately provide better treatment. References Corcoran, B M (1997) Idiopathic pulmonary fibrosis: an emerging disease in dogs. In, Paper Synopses, WSAVA 1997, p.42 Corcoran, Cobb, Martin et al (1999) Chronic pulmonary disease in West Highland white terriers. Vet Record 144, 611-616. Martin, M. (1998) Progressive lung disease with pulmonary crackles in 18 terrier breed dogs. In, Paper Synopses, BSAVA Congress, p.287 Moneva Jordan et al (2001) Sick sinus syndrome in nine West Highland White Terriers. Veterinary Record 148, 142-147.