Methods for Estimating Areas under Receiver-Operating Characteristic Curves: Illustration with Somatic-Cell Scores in Subclinical Intramammary Infections

in Preventive Veterinary Medicine (1999), 41(2-3), 75-88

The aim of this study was to demonstrate receiver-operating characteristic (ROC) methodology in the context of bovine intramammary infection (IMI). Quarter somatic cell scores (SCS) were available to ... [more ▼]

The aim of this study was to demonstrate receiver-operating characteristic (ROC) methodology in the context of bovine intramammary infection (IMI). Quarter somatic cell scores (SCS) were available to evaluate quarter IMI, and the final IMI diagnosis was made from milk bacteriologic cultures. Data consisted of 11,453 quarter-milk samples collected on 2084 clinically healthy cows located in 154 Belgian herds. Bacteriological analyses showed 16.2%, 7.2%, and 11.9% of quarters infected with coagulase-positive Staphylococcus spp., Streptococcus agalactiae, and coagulase-negative Staphylococcus spp., respectively. The ROC curve indicated all the combinations of sensitivity and specificity that quarter SCS was able to provide as a test to identify quarter IMI. Among parametric, semi-parametric, and non-parametric methods to estimate area under ROC curves, the parametric method seemed the least appropriate for analyzing SCS in this study. With the non-parametric method, the total area under the ROC curves showed quarter SCS could identify quarter IMI with an overall accuracy of 69%, 76%, and 59% for coagulase-positive Staphylococcus spp., S. agalactiae, and coagulase-negative Staphylococcus spp., respectively. Parametric and non-parametric statistical tests showed that overall SCS diagnostic capability was significantly (p<0.01) different from chance and was different (p<0.01) across the three bacteria. However, the SCS thresholds yielding the highest percentage of quarters correctly classified as infected (for the observed prevalence and for equal costs assigned to false-positive and false-negative results) were so high that they had no practical value. The major advantage of ROC analysis is the comprehensive description of the discrimination capacity of SCS for all possible choices of critical values. The major disadvantage is the dependency upon the gold standard used for the final diagnosis--but recent improvements of the methodology will correct the problem. [less ▲]

A new acute respiratory distress syndrome in newborn calves : clinical, laboratory and post-mortem findings

in In Proceedings of the 15th Comparative Respiratory Society Meeting (1997)

Dermatophylose équine: revue à partir d'un cas clinique

in Annales de Médecine Vétérinaire (1996), 140(2), 125-129

From a clinical case of equine dermatophilosis, a short review of literature is proposed. The aetiology, causal factors, symptoms and lesions are brievely reviewed. Therapeutics and prophylaxis are ... [more ▼]

From a clinical case of equine dermatophilosis, a short review of literature is proposed. The aetiology, causal factors, symptoms and lesions are brievely reviewed. Therapeutics and prophylaxis are outlined. [less ▲]

Three cases of Pemphigus Foliaceus in horses

in Proceedings of the XXVth Congress of the World Veterinary Association (1995)

Reduced cardiac functional capacity as a consequence of the double-muscled conformation selection in the Belgian White and Blue breed.

in Bovine Practitioner (1995), 29

Bilateral diaphragmatic paralysis in a pony

in Proceedings of the 4th Congress of the European Society of Veterinary Internal Medicine, Brussels, Belgium (1994)

Control of breathing in healthy and Pasteurella exposed calves after 5-HT2 receptor blockade

in Pflügers Archiv : European Journal of Physiology (1994), 426

Ventilatory effects of rebreathing CO2 in two breeds of calves

in Archives Internationales de Physiologie et de Biochimie (1992)

Fonction pulmonaire de la chèvre : normes et spécificités

in Annales de Médecine Vétérinaire (1991), 135

Assessment of respiratory diseases and therapeutic intervention by the forced oscillation technique in feedlot cattle

in Research in Veterinary Science (1990), 49(3), 319-322

The forced oscillation technique was used to study pulmonary function in bulls during naturally acquired pulmonary-gastrointestinal disease complex known as shipping fever and as it was treated with two ... [more ▼]

The forced oscillation technique was used to study pulmonary function in bulls during naturally acquired pulmonary-gastrointestinal disease complex known as shipping fever and as it was treated with two different antibiotics. Fifteen double-muscled bulls of the Belgian White and Blue breed were investigated. Clinical, serological and pulmonary function values were recorded during and after naturally occurring respiratory disease. Total respiratory resistance (Rrs) and reactance (Xrs) were measured by the forced oscillation technique. The antibiotic ceftiofur (group A, n = 10) and oxytetracycline (group B, n = 5) were given over three days. A large increase of Rrs at low frequencies with a marked negative frequency dependence, an increase of the resonant frequency, and a decrease of Xrs were recorded in the initial stage of the disease. The parameters returned to normal values seven days later. Clinical evidence of recovery was more marked in group A than in group B. These results show that moderate shipping fever induces acute small and large airway obstruction which responds to appropriate antibiotic therapy. [less ▲]