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An Urban Experience
C. Clercx1
1University of Liège, Department of Clinical Sciences of Companion Animals and Equine, LIEGE-SART TILMAN, Belgium
In dogs, idiopathic pulmonary fibrosis (CIPF) has been described with a clear breed predisposition; indeed, canine IPF affects mainly the West Highland White Terriers (WHWT). It has been described, much more rarely, in other terrier breeds, such as the Bull terrier
or the Staffordshire Bull terrier (1)(2), although it is not known if pulmonary fibrosis is exactly the same as in the WHWT breed. Since its first description in 1999 (3), several studies have been conducted to improve the clinical characterisation of the disease, expand
our understanding about the pathophysiology and identify biomarkers of the disease. At the present time, however, several aspects of CIPF remain unknown. A similar condition exists in humans(4). In man, idiopathic pulmonary fibrosis (IPF) is an emerging progressive fibrotic lung disease with an unknown aetiology, poorly understood pathophysiology and a poor prognosis.
Etiology and Pathophysiology
As in humans, the etiopathogenesis of IPF in dogs is
not known. There is emerging evidence for the role
of genetic factors in the development of the disease. Most cases appear to be caused by an interaction between a specific environmental exposure and a genetic predisposition. In dogs, confinement to related terrier breeds combined with very low incidence within non-terrier breeds also strongly suggests an underlying genetic cause. Current prevailing hypotheses for the condition focus on dysregulated epithelial–mesenchymal interactions promoting a cycle of continued epithelial
cell injury and fibroblast activation leading to fibrosis. Multiple abnormalities in a myriad of biological pathways affecting inflammation and wound repair, including matrix regulation, epithelial reconstitution, the coagulation cascade, neovascularization, and anti-oxidants, modulate this defective process and promote fibrogenesis.
Clinical presentation
The disease is clinically characterized by progressive dyspnea, exercise intolerance (1,5). As it occurs gradually in old animals, owners may first think that symptoms
are only related to ageing. Most dogs also present chronic cough. In severe cases, exercise intolerance is obvious and the tongue can get a bluish appearance. Pronounced crackles are a hallmark of the disease; they can be heard on auscultation, and can sometimes be heard by the owners without stetoscope. The general body condition is good and dogs do not lose weight and remain happy living pets for a prolonged period.
Diagnosis and differential diagnosis
The disease is not easily distinguished from chronic bronchitis, which may co-exist. In IPF, cough can be attributed with tracheal collapse, which is found in
a proportion of affected dogs, probably due to the increased work of breathing. Crackles might suggest cardiogenic edema; however, such a diagnosis is not compatible with other clinical findings. In some dogs, crackles can even be heard without stethoscope
when the dog is breathing with an open mouth (1). Radiographic, bronchoscopic, hematologic, or biochemical findings are not specific, but help to eliminate other possible disorders. Echocardiography may reveal signs of secondary pulmonary arterial hypertension. Arterial blood gas analysis shows low levels of PaO2 and a high alveolar–arterial oxygen gradient(1). The 6 minutes walking test, a totally not invasive exercise testing, increasingly used in clinical human practice for exercise capacity evaluation, may be used in dogs with IPF (6). Other noninvasive pulmonary function tests are rarely used in veterinary practice. Lung imaging using high-resolution CT is currently often used to evaluate IPF in humans, and is the test of choice in dogs as well (7) and that it can be performed under sedation in most dogs(8). A recent study reported
that However, ultimate confirmation of the diagnosis requires lung biopsy and histopathology (9). With the goal to better understand this fatal disease and to offer novel therapeutic approaches for the future, as well as
to improve its diagnosis, a collaborative research project has jointly initiated a few years ago by our team at the University of Liège and Professor Rajamäki from the University of Helsinki. A dedicated website has been
built (, which aims to share objectives, progress and information relating to this research project and to improve communications between veterinarians, dog’s owners and breeders around the disease.

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