Long‐Term Outcome and Use of 6‐Minute Walk Test in West Highland White Terriers with Idiopathic Pulmonary Fibrosis

Abstract

BackgroundIdiopathic pulmonary fibrosis (IPF) is an incurable interstitial lung disease occurring mainly in West Highland White Terriers (WHWTs). The effects of IPF on survival and on exercise tolerance in WHWTs are unknown.ObjectivesTo evaluate survival, prognostic factors, and exercise tolerance in WHWTs with IPF.AnimalsPrivately owned WHWTs; 15 with IPF and 11 healthy controls.MethodsProspective case‐control study conducted in 2007–2012. For survival, descriptive statistics and Kaplan–Meier (KM) survival curves with Cox proportional hazard ratios were performed. For the prognostic factor study, KM curves, Cox regression analysis, and logistic regression models were used. The 6‐minute walk test (6MWT) was used for measurement of exercise tolerance.ResultsThe median IPF‐specific survival of deceased WHWTs (7/15) with IPF was 32 (range 2–51) months from onset of clinical signs. The risk of death from birth in WHWTs with IPF in age‐adjusted Cox model was significantly higher (hazard ratio 4.6; 95% confidence interval 1.05–19.74, P = .04) than in control WHWTs. No significant prognostic factors were identified. In 6MWT, WHWTs with IPF walked a shorter distance, median 398 m (range 273–519 m), than healthy controls, median 492 m (420–568 m), P = .05, and the partial pressure of oxygen in arterial blood in diseased dogs had a moderate positive correlation with walking distance (Kendall′s tau‐b = 0.69, P = .06).Conclusion and Clinical Importance IPF had a negative impact on life expectancy, but individual survival varied considerably. 6MWT proved to be a well‐tolerated, noninvasive test to evaluate exercise tolerance.

Comparison Between Sedation and General Anesthesia for High Resolution Computed Tomographic Characterization of Canine Idiopathic Pulmonary Fibrosis in West Highland White Terriers

“…Arterial blood gas analysis was performed in 10 affected dogs and revealed hypoxemia in all dogs with a median of 58.9 mm Hg (range 50.6–65.0) (laboratory reference range: 80–100 mm Hg). The 6‐min walking test was performed in 10 affected West Highland white terriers and a decreased walked distance was recorded in seven dogs (median 350 m, range 232–488) (reference: >420) . Bronchoscopy was performed in 10 affected dogs and identified tracheal collapse (10 dogs), bronchi mucosal irregularity (nine dogs), bronchomalacia (four dogs), bronchiectasis (two dogs), and the presence of a moderate amount of mucus (seven dogs).…”

Noninvasive Assessment of Neuromuscular Disease in Dogs: Use of the 6‐minute Walk Test to Assess Submaximal Exercise Tolerance in Dogs with Centronuclear Myopathy

“…In contrast to the instrumentation needed to carry out those tests, the 6MWT does not require any equipment beyond a timer and the ability to measure the length of the area traversed. Thus, the 6MWT is an accessible and easy‐to‐learn technique for both research and clinical settings . The 6MWT has been used successfully to evaluate exercise tolerance in dogs of different sizes (eg, beagle, West Highland White terrier, Labrador retriever, hound), has been shown to be reproducible in pet dogs and in the research setting, and requires less acclimatization time than do treadmill evaluations .…”

“…The six‐minute walk test (6MWT) has been used to quantitate exercise tolerance in dogs with systemic disease, but has not been evaluated in those with neuromuscular disease. This test measures the linear distance walked by individual dogs when dogs are allowed to walk at their own pace for 6 minutes.…”

“…Using this test, statistically significant differences in walking distance have been found between control dogs and dogs with pulmonary fibrosis, heart failure, and obesity . In these studies, the 6MWT was reported as a low cost, reproducible, and easy‐to‐implement test of exercise tolerance . Similarly, the test has been used to assess exercise capacity in humans with chronic disease (eg, cardiac dysfunction, multiple sclerosis), and in those recovering from critical illness, and is used routinely to assess ambulatory capacity in children affected by Duchènne's muscular dystrophy .…”

Fluoroscopic Estimation of Thoracic Dimensional Changes in Healthy Dogs

“…More routinely available tests of pulmonary function include arterial blood analysis and the 6‐minute walk test (6 MWT). The 6 MWT has proven particularly useful as a surrogate measure of cardiopulmonary dysfunction . Direct measurement of lung compliance requires intubation and anesthesia and has a low sensitivity for mild‐to‐moderate disease .…”